  MISCELLANEOUS CURIOSITIES.—(Concluded.) Lama—Nun—Mahometan Paradise—Opinions respecting Hell—London—Coins of the Kings of England—Singular Calculations respecting the National Debt—Moral and Physical Thermometer.—Conclusion. Lama.—This is the sovereign pontiff, or rather god, of the Asiatic Tartars, inhabiting the country of Barantola. The lama is not only adored by the inhabitants of the country, but also by the kings of Tartary, who send him rich presents, and go in pilgrimage to pay him adoration, calling him lama congiu, i. e. “god, the everlasting father of heaven.” He is never to be seen but in a secret place of his palace, amidst a great number of lamps, sitting crosslegged upon a cushion, and adorned all over with gold and precious stones; where at a distance they prostrate themselves before him, it not being lawful for any to kiss his feet. He is called the great lama, or lama of lamas; that is, “priest of priests.” The orthodox opinion is, that when the grand lama seems to die either of old age or infirmity, his soul in fact only quits a crazy habitation to look for another younger or better; and it is discovered again in the body of some child, by certain tokens known only to the lamas, or priests, in which order he always appears. A particular account of the pompous ceremonies attending the inauguration of the infant lama in Thibet, is given in the first volume of the Asiatic Researches. The emperor of China appears, on such occasions, to act a very conspicuous part, in giving testimony of his respect and zeal for the great religious father of his faith. The twenty-eighth day of the seventh moon, corresponding nearly (as their year commences with the vernal equinox) with the middle of October, is reckoned the most auspicious for the ceremony of inauguration. The procession, on these occasions, from Terpaling to the Teeshoo Loombo, is conducted with such slow and majestic solemnity, that though the distance is only twenty miles, it takes up three days. The crowd of spectators is immense. The three next days are spent in the inauguration, in delivering the presents sent by the emperor to the lama, and in the public festivals on the occasion; during which, all who are at the capital are entertained at the public expense, and alms are distributed liberally to the poor. Universal rejoicings prevail throughout Thibet; banners are unfurled on all their fortresses, the peasantry fill Some particulars respecting Nuns.—A nun is a woman dedicated to the severer duties of religion, secluded in a cloister from the world, and debarred by a vow from the converse of men. When a woman is to be made a nun, the habit, veil, and ring of the candidate, are carried to the altar; and she herself, accompanied by her nearest relations, is conducted to the bishop, who, after mass and an anthem (the subject of which is, “that she ought to have her lamp lighted, because the bridegroom is coming to meet her,”) pronounces the benediction: then she rises up, and the bishop consecrates the new habit, sprinkling it with holy water. When the candidate has put on her religious habit, she presents herself before the bishop, and sings on her knees, Ancilla Christi sum, &c.; then she receives the veil, and afterwards the ring, by which she is married to Christ; and lastly, the crown of virginity. When she is crowned, an anathema is denounced against all who shall attempt to make her break her vows. In some few instances, perhaps, nunneries and monasteries may have been useful to morality and religion, as well as to literature, but, in the gross, they have been highly prejudicial; and however pious they may appear in theory, in fact they are unnatural and impious. Mahometan Paradise.—The paradise of the Mahometans is said by them to be situated above the seven heavens, or in the seventh, and next under the throne of God; and, to express the amenity of the place, they tell us that the earth of it is of the finest wheat flour, or of the purest musk, or of saffron; and that its stones are pearls and jacinths, the walls of its buildings enriched with gold and silver, and the trunks of all its trees of gold, amongst which the most remarkable is the tree luba, or tree of happiness. They pretend that this tree stands in the palace of Mahomet, though a branch of it will reach to the house of every true believer, loaded with pomegranates, grapes, dates, and other fruits, of surprising size, and delicious tastes, unknown to mortals. If a man desires to eat of any particular kind of fruit, it will immediately be presented to him; or if he chooses flesh, birds ready dressed will be set before him, and such as he may wish for. They add that this tree will supply the blessed, But all these glories will be eclipsed by the resplendent and exquisite beauty of the girls of paradise, the enjoyment of whose company will constitute the principal felicity of the faithful. These (they say) are not formed of clay, as mortal women, but of pure musk, and are, as their prophet often affirms in his Koran, free from all the natural defects and inconveniences incident to the sex. Being also of the strictest modesty, they keep themselves secluded from public view, in pavilions of hollow pearls, so large, that, as some traditions have it, one of them will be no less than sixteen, or, as others say, sixty miles long, and as many broad. With these the inhabitants of paradise may taste pleasures in their height; and for this purpose will be endowed with extraordinary abilities, and enjoy a perpetual youth. Opinions respecting Hell.—The hell of the ancient heathens was divided into two mansions: the one called Elysium, on the right hand, pleasant and delightful, appointed for the souls of good men; the other called Tartarus, on the left, a region of misery and torment, appointed for the wicked. The latter only was hell, in the present restrained sense of the word. The philosophers were of opinion, that the infernal regions were at an equal distance from all the parts of the earth; nevertheless, it was the opinion of some, that there were certain passages which led thither, as the river Lethe near the Syrtes, and the Acherusian cave in Epirus. At Hermione, it was thought, that there was a very short way to hell; for which reason the people of that country never put the fare into the mouths of the dead to pay their passage. The Jews placed hell in the centre of the earth, and believed it to be situated under waters and mountains. According to them, there are three passages leading to it: the first is in the wilderness, and by that Korah, Dathan, and Abiram Among Christians, there are two controverted questions in regard to hell; the one concerning the locality, the other the duration of its torments:—The locality of hell, and the reality of its fire, began first to be controverted by Origen. That father, interpreting the scripture account metaphorically, makes hell to consist, not in external punishments, but in a consciousness or sense of guilt, and a remembrance of past pleasures. Among the moderns, Mr. Whiston advanced a new hypothesis. The comets, he thinks, are so many hells, appointed in their orbits alternately to carry the damned into the confines of the sun, there to be scorched by its violent heat, and then to return with them beyond the orb of Saturn, there to starve them in those cold and dismal regions. Another modern author, Mr. Swinden, supposes the sun to be the local hell. However difficult it may be to ascertain the local place of hell, we may rest assured God will find both place and means to punish the obstinately wicked. London.—This metropolis is unparalleled, in extent and opulence, in the whole habitable globe, except, perhaps, Pekin in China, Jeddo in Japan, and Houssa in Africa; which are all said to be larger. It comprehends, besides London, Westminster, and Southwark, no less than forty-five villages, of considerable extent, independent of a vast accession of buildings upon the open fields in the vicinity. Its length is nearly eight miles, its breadth three, and its circumference twenty-six. It contains above 8000 streets, lanes, alleys, and courts, and more than 65 different squares. Its houses, warehouses, and other buildings, make 162,000, besides 246 churches and chapels, 207 meeting houses for dissenters, 43 chapels for foreigners, and 6 synagogues for the Jews, which in all make 504 places of public worship. The number of inhabitants, during the sitting of parliament, is estimated at 1,250,000. Among these are found about 50,000 common prostitutes, and no less than 60,000 thieves, coiners, and other bad persons of all descriptions. The annual depredations on the public, by this numerous The numbers of bullocks, sheep, lambs, calves, hogs, and sucking pigs, purchased at the Smithfield markets, and annually consumed in the metropolis, are in the following proportion: bullocks 110,000; sheep and lambs 776,000; calves 210,000; hogs 210,000; sucking pigs 60,000. Markets for hay, Tuesday, Thursday, and Saturday. The markets for the sale of provisions are numerous, and amply supplied with every sort, generally of the most excellent kind: the bread generally fine and sound. Besides animal food and bread, there are no less than 6,980,000 gallons of milk [and water] annually consumed here: of vegetables and fruit, there are 10,000 acres of ground near the metropolis, cultivated wholly for vegetables; and about 4000 acres of fruit. Of wheat, coals, ale, and porter, &c. the annual consumption is as follows: of wheat, 700,000 quarters; of coals 600,000 chaldrons; of ale and porter 1,113,500 barrels; of spirits and compounds 11,146,782 gallons; of wine 32,500 tons; of butter 16,600,000 pounds; and of cheese 21,100,000 pounds. Fish and poultry are sometimes excessively dear, and the quantities consumed are comparatively small. Coins of the Kings of England.—The silver Penny, which was first circulated during the Heptarchy, continued to be the general coin after the kingdom had been united under one head, and extends, in a continued series, from Egbert almost to the present reign. The only kings wanting are Edmund Ironside, Richard I., and John. At first the penny weighed twenty-two and a half grains, but towards the close of the reign of Edward III. it fell to eighteen grains; in that of Edward IV. to twelve. In the time of Edward VI. it was reduced to eight grains; and in queen Elizabeth’s reign to 723/31 grains, at which it still continues. Shillings were first coined by Henry VII. in 1503; at first they were called testoon, from the teste, tÊte, or head of the king, upon them; the name shilling being derived from the German schelling, under which name coins had been struck at Hamburgh in 1407. The crown was first coined in its present form by Henry VIII. The half-crown, six-pence, and three-pence, were coined by Edward VI. In 1558, queen Elizabeth coined three-halfpenny, and in 1561, three-farthing pieces; but they were discontinued in 1582. Gold was coined in England by Henry III. in 1257; the piece was called a gold penny, and was larger than the silver one, and the execution by no means bad for the time. The series of gold coinage, however, commences properly from Edward III. In 1344, this monarch first struck florins, in imitation of those in Italy; and it is remarkable, that though these coins, at the time they were first issued, bore only six shillings value, they were (even before the late increased value of gold) intrinsically worth nineteen shillings; so much has the value of gold increased since that time. The half and quarter florin were struck at the same time, but only the last has been found. The florin being found inconvenient, gave place to the noble, of six shillings and eight-pence value, and exactly half a mark. The latter had its name from being a limited sum in accounts; and was eight ounces in weight, two-thirds of the money pound. The noble had its name from the nobility of the metal; the gold of which it is coined being of the finest sort. Sometimes it was called rose-noble, from both sides being impaled in an undulating circle. It continued, with the half and quarter noble, to be the only gold coin till the angels of Edward IV. appeared in 1465. These had their name from the image of Michael and the Dragon which they bore. The angelites, of three shillings and four-pence value, were substituted in their place. In 1527, Henry VIII. added to the gold coins the crown and half-crown at their present value; the same year he gave sovereigns of twenty-two shillings, and six-pence, and ryals of eleven shillings and three-pence, angels at seven shillings and six-pence, and nobles at their old value of six shillings and eight-pence. In 1546 he caused sovereigns to be coined of the value of twenty shillings, and half sovereigns in proportion. On the union of the two crowns, James gave the sovereign the name of unite; the value continuing twenty shillings, as Singular Calculation respecting the National Debt.—The national debt, funded and unfunded, on the 5th of January, 1811, was £811,898,811, which are equal to 773,236,267 guineas, which, at 5 dwts. 8 grains each guinea, weigh 6312 tons, 11 cwt. 3 qrs. 5 lbs. 1 oz. 6 drs. nearly, avoirdupois. Now supposing a waggon and five horses to extend in length twenty yards, and to carry two and a half tons of the said guineas, the number of teams necessary to carry the whole would extend in length twenty-eight miles twenty-three yards. To count the debt in shillings, at the rate of thirty shillings in a minute, for ten hours a day, and six days in a week, would take 2,469 years, 306 days, 17 hours, and 30 minutes, nearly. Its height in guineas, supposing twenty guineas in thickness to be an inch, would be 610 miles, 339 yards, 9 inches; and supposing each guinea an inch in diameter, they would extend in a right line, 12,203 miles, 150 yards, 7 inches. Moreover, the said guineas would cover, in space, 348 acres, 2 roods, 202 yards, nearly. And, lastly, in shillings, each being an inch in diameter, would cover 7319 acres, 1 rood, and 349 yards! A ——— Liquors, with their Effects in their usual Order. Conclusion. Thus we have conducted our reader through some of the principal curiosities of Nature and Art, Science and Literature. We trust he has found both amusement and instruction. Our object has been, throughout the work, to assist the reader in looking through Nature up to Nature’s God. All second causes derive their origin, permanency, and efficacy from Him alone. Since, then, the Lord God is himself the source and perfection of all beauty and excellency, the author of our existence, and the bountiful giver of all good gifts; we undoubtedly ought to love him with our whole hearts, and to serve him with all our powers; we ought to reverence his majesty and authority, and endeavour above all things to obtain his favour; we ought to devote ourselves entirely to his service, and make all our actions tend to the advancement of his glory. And as his mercy and goodness are unbounded, so should be our gratitude and praise. Jehovah reigns: let ev’ry nation hear, APPENDIX A Person having an even Number of Counters in one Hand, and an odd Number in the other, to tell in which Hand each of them is. Desire the person to multiply the number in his right hand by three, and the number in his left by two. Bid him add the two products together, and tell you whether the sum be odd or even. If it be even, the even number is in the right hand; but if it be odd, the even number is in the left hand.
A Person having fixed on a Number in his Mind, to tell him what Number it is. Bid him quadruple the number thought on, or multiply it by 4; and having done this, desire him to add 6, 8, 10, or any even number you please, to the product; then let him take the half of this sum, and tell you how much it is; from which, if you take away half the number you desired him at first to add to it, there will remain the double of the number thought on. Example.
Therefore 5 was the number thought on. Another Method of discovering a Number thought on. After the person has fixed on a number, bid him double it, and add 4 to that sum; then let him multiply the whole by 5, and to that product add 12; desire him also to multiply this sum by 10, and after having deducted 302 from the product, to tell you the remainder, from which, if you cut off the last two figures, the number that remains will be the one thought on. Example.
which, by striking off the last two figures, gives 7,—the number thought on. To tell the Number a Person has fixed upon, without asking him any Questions. The person having chosen any number in his mind, from 1 to 15, bid him add one to it, and triple the amount. Then, If it be an even number, let him take the half of it, and triple that half; but if it be an odd number, he must add 1 to it, and then halve it, and triple that half. In like manner let him take the half of this number, if it be even, or the half of the next greater, if it be odd; and triple that half.
Thus, if he be obliged to add 1 only at the first step, or halving, either 4 or 8 was the number thought on; if there were a necessity to add 1 both at the first and second steps, either 2 or 10 was the number thought on, &c. And which of the two numbers is the true one may always be known from the last step of the operation; for if 1 must be added before the last half can be taken, the number is in the second column, or otherwise in the first, as will appear from the following examples:
From which it appears, that it was necessary to add 1 both at the second and third steps, or halvings; and therefore, by the table, the number thought on is either 1 or 9. And as the last number was obliged to be augmented by 1 before the half could be taken, it follows also, by the above rule, that the number must be in the second column; and consequently it is 9.
And as the last number required no augmentation before its half could be taken, it follows also, by the above rule, that the number must be in the first column; and consequently it is 6. A curious Recreation, usually called—The Blind Abbess and her Nuns. A blind abbess visiting her nuns, who were twenty-four in number, and equally distributed in eight cells, built at the four corners of a square, and in the middle of each side, finds an equal number in every row, containing three cells. At a second visit, she finds the same number of persons in each row as before, though the company was increased by the accession of four men. And coming a third time, she still finds the same number of persons in each row, though the four men were then gone, and had each of them carried away a nun.
Let the nuns be first placed as in fig. 1, three in each cell; then when the four men have got into the cells, there must be a man placed in each corner, and two nuns removed thence to each of the middle cells, as in fig. 2, in which case there will evidently be still nine in each row; and when the four men are gone, with the four nuns with them, each corner cell must contain four nuns, and every other cell one, as in fig. 3; it being evident, that in this case also, there will still be nine in a row, as before. Any Number being named, to add a Figure to it, which shall make it divisible by 9. Add the figures together in your mind which compose the number named; and the figure which must be added to this sum, in order to make it divisible by 9, is the one required. Suppose, for example, the number named was 8654; you find that the sum of its figures is 23; and that 4 being added to this sum will make it 27; which is a number exactly divisible by 9. This recreation may be diversified, by your specifying, before the sum is named, the particular place where the figure shall be inserted, to make the number divisible by 9; for it is exactly the same thing, whether the figure be put at the end of the number, or between any two of its digits. A Person having made choice of several Numbers, to tell him what Number will exactly divide the Sum of those which he has chosen. Provide a small bag, divided into two parts; into one of which put several tickets, numbered 6, 9, 15, 36, 63, 120, 213, 309, or any others you please, that are divisible by 3, and in the other part put as many different tickets marked with the number 3 only. Draw a handful of tickets from the first part, and, after shewing them to the company, put them into the bag again; and having opened it a second time, desire any one to take out as many tickets as he thinks proper. When he has done this, open privately the other part of the bag, and tell him to take out of it one ticket only. You may then pronounce, that this ticket shall contain the number by which the amount of the other numbers is divisible; for, as each of these numbers is some multiple of 3, their sum must evidently be divisible by that number. This recreation may also be diversified, by marking the tickets in one part of the bag with any numbers which are divisible by 9, and those in the other part of the bag with the number 9 only; the properties of both 9 and 3 being the same; or if the numbers in one part of the bag be divisible by 9, the other part of the bag may contain tickets marked both with 9 and 3, as every number divisible by 9 is also divisible by 3. To find the Difference between any two Numbers, the greater of which is unknown. Take as many 9’s as there are figures in the less number, and subtract the one from the other. Let another person add that difference to the larger number; and then, if he take away the first figure of the amount, and add it to the remaining figures, the sum will be the difference of the two numbers, as was required. Suppose, for example, that Matthew, who is 22 years of He privately deducts 22, his own age, from 99, and the difference, which is 77, he tells Henry to add to his age, and to take away the first figure from the amount. Then if this figure, so taken away, be added to the remaining ones, the sum will be the difference of their ages; as, for instance:
A Person striking a Figure out of the Sum of two given Numbers, to tell him what that Figure was. Such numbers must be offered as are divisible by 9; such, for instance, as 36, 63, 81, 117, 126, 162, 207, 216, 252, 261, 306, 315, 360, and 432. Then let a person choose any two of these numbers, and after adding them together in his mind, strike out any one of the figures he pleases, from the sum. After he has done this, desire him to tell you the sum of the remaining figures; and that number which you are obliged to add to this amount, in order to make it 9, or 18, is the one he struck out. For example, suppose he chose the numbers 126 and 252, the sum of which is 378. Then, if he strike out 7 from this amount, the remaining figures, 3 and 8, will make 11; to which 7 must be added to make 18. If he strike out the 3, the sum of the remaining figures, 7 and 8, will be 15; to which 3 must be added, to make 18; and so in like manner, for the 8. By knowing the last Figure of the Product of two Numbers, to tell the other Figures. If the number 73 be multiplied by each of the numbers in the following arithmetical progression, 3, 6, 9, 12, 15, 18, 21. 24, 27, the products will terminate with the nine digits, in Let therefore a little bag be provided, consisting of two partitions, into one of which put several tickets, marked with the number 73; and into the other part, as many tickets numbered 3, 6, 9, 12, 15, 18, 21, 24, and 27. Then open that part of the bag which contains the number 73, and desire a person to take out one ticket only; after which, dexterously change the opening, and desire another person to take a ticket from the other part. Let them now multiply their two numbers together, and tell you the last figure of the product, and you will readily determine, from the foregoing series, what the remaining figures must be. Suppose, for example, the numbers taken out of the bag were 73, and 12; then, as the product of these two numbers, which is 876, has 6 for its last figure, you will readily know that it is the fourth in the series, and that the remaining figures are 87. A curious Recreation with a Hundred Numbers, usually called the Magical Century. If the number 11 be multiplied by any one of the nine digits, the two figures of the product will always be alike, as appears from the following example:—
Now, if another person and yourself have fifty counters apiece, and agree never to stake more than ten at a time, you may tell him, that if he will permit you to stake first, you will always undertake to make the even century before him. In order to this you must first stake one, and remembering the order of the above series, constantly add to what he stakes as many as will make one more than the numbers 11, 22, 33, &c. of which it is composed, till you come to 89; after which, the other party cannot possibly make the even century himself, or prevent you from making it. If the person who is your opponent have no knowledge of numbers, you may stake any other number first, under 10, provided you afterwards take care to secure one of the last terms, 56, 67, 78, &c.: or you may even let him stake first, provided you take care afterwards to secure one of these numbers. A Person in Company having privately put a Ring on one of his fingers, to Name the Person, the Hand, the Finger, and even the Joint on which it is placed. Desire a third person to double the number of the order in which the wearer of the ring stands, and add 5 to that number, then multiply that sum by 5, and to the product add 10. Let him then add 1 to the last number, if the ring be on the right hand, and 2 if on the left, and multiply the whole by 10: to this product he must add the number of the finger, beginning with the thumb, and multiply the whole again by 10. Desire him then to add the number of the joint; and lastly, to increase the whole by 35. This being done, he is to declare the amount of the whole, from which you are to subtract 3535; and the remainder will consist of four figures, the first of which will give the place in which the person stands, the second the hand, 1 denoting the right, and 2 the left hand, the third number the finger, and the fourth the joint. Example. Suppose the person stands the second in order, and has put the ring on the second joint of the little finger of the left hand:
To make a Deaf Man hear the Sound of a Musical Instrument. It must be a stringed instrument, with a neck of some length, as a lute, a guitar, or the like; and before you begin to play, you must by signs direct the deaf man to take hold with his teeth of the end of the neck of the instrument; for then, if one strikes the strings with the bow one after another, the sound will enter the deaf man’s mouth, and be conveyed to the organ of hearing through a hole in the palate, and thus the deaf man will hear with a great deal of pleasure the sound of the instrument, as has been several times experienced; nay, those who are not deaf may make the experiment upon themselves, by stopping their ears so as not to hear the instrument, and then holding the end of the instrument in their teeth, while another touches the strings. When two Vessels or Chests are like one another, and of equal Weight, being filled with different Metals, to distinguish the one from the other. This is easily resolved, if we consider that two pieces of different metals, of equal weight in air, do not weigh equally in water, because that of the greatest specific gravity takes up a lesser space in water; it being a certain truth, that any metal weighs less in water than in air, by reason of the water, the room of which it fills; for example, if the water weighs a pound, the metal will weigh in that water a pound less than in the air: this gravitation diminishes more or less, according as the specific gravity of the metal is greater than that of the water. We will suppose, then, two chests perfectly like one another, of equal weight in the air, one of which is full of gold, and the other of silver; we weigh them in water, and that which then weighs down the other must needs be the gold chest, the specific gravity of gold being greater than that of silver, which makes the gold lose less of its gravitation in water than silver. We know by experience, that gold loses in water about an eighteenth part only, whereas silver loses near a tenth part; so that if each of the two chests weighs in the air, for example, 180 pounds, the chest that is full of gold will lose in the water ten pounds of its weight; and the chest that is full of silver will lose eighteen: that is, the chest full of gold will weigh 170 pounds, and that of silver only 162. Or, if you will, considering that gold is of a greater specific gravity than silver, the chest full of gold, though similar and To find the Burden of a Ship at Sea, or in a River. It is a certain truth, that a ship will carry a weight equal to that of a quantity of water of the same bulk with itself; subtracting from it the weight of the iron about the ship, for the wood is of much the same weight with water; and so, if it were not for the iron, a ship might sail full of water. The consequence of this is, that, however a ship be loaded, it will not totally sink, as long as the weight of its cargo is less than that of an equal bulk of water: now, to know this bulk or extent, you must measure the capacity or solidity of the ship, which we here suppose to be 1000 cubical feet, and multiply that by 73 pounds, the weight of a cubical foot of sea-water; then you have in the product 73,000 pounds for the weight of a bulk of water equal to that of the ship; so that in this example, we may call the burden of the ship 73,000 pounds, or 36½ tons, reckoning a ton 2,000 pounds, that being the weight of a ton of sea-water; if the cargo of this ship exceeds 36½ tons, she will sink; and if her loading is just 73,000 pounds, she will swim very deep in the water upon the very point of sinking; so that she cannot sail safe and easy, unless her loading be considerably short of 73,000 pounds weight; if the loading come near to 73,000 pounds, as being, for example, just 36 tons, she will swim at sea, but will sink when she comes into the mouth of a fresh water river; for this water being lighter than sea-water will be surmounted by the weight of the vessel, especially if that weight is greater than the weight of an equal bulk of the same water. To Measure the Depth of the Sea. Tie a great weight to a very long cord, or rope, and let it fall into the sea till you find it can descend no further, which will happen when the weight touches the bottom of the sea: if the quantity or bulk of water, the room of which is taken up by the weight, and the rope, weighs less than the weight and rope themselves; for if they weigh more, the weight would cease to descend, though it did not touch the bottom of the sea. Thus one may be deceived in measuring the length of a rope let down into the water, in order to determine the depth of the sea; and therefore, to prevent mistakes, you had best tie to the end of the same rope another weight heavier than the former, and if this weight does not sink the rope deeper than Method of Melting Steel, and causing it to Liquefy. Heat a piece of steel in the fire, almost to a state of fusion, then holding it with a pair of pincers or tongs, take in the other hand a stick of brimstone, and touch the piece of steel with it: immediately after the contact, you will see the steel melt and drop like a liquid. How to dispose two little Figures, so that one shall light a Candle, and the other put it out. Take two little figures of wood or clay, or any other materials you please, only taking care that there is a little hole at the mouth of each: put in the mouth of one a few grains of bruised gunpowder, and a little bit of phosphorus in the mouth of the other, taking care that these preparations are made beforehand. Then take a lighted wax candle, and present it to the mouth of the figure with the gunpowder, which, taking fire, will put the candle out; then present your candle, having the snuff still hot, to the other figure; it will immediately light again by means of the phosphorus. You may propose the same effects to be produced by two figures drawn on a wall with a pencil or coal, by applying with a little starch, or water, a few grains of bruised gunpowder to the mouth of one, and a bit of phosphorus to the mouth of the other. The Camera Obscura, or Dark Chamber. We shall here give a short description of this optical invention; for though it is very common, it is also very pleasing: but every one knows not how to construct it. Make a circular hole in the shutter of a window, from whence there is a prospect of the fields, or any other object not too near: and in this hole place a convex glass, either double or single, whose focus is at the distance of five or six feet: the distance should not be less than three feet; if it be, the images will be too small, and there will not be sufficient room for the spectators to stand conveniently; on the other hand, If you place a moveable mirror without the window, by turning it more or less, you will have on the paper all the objects that are on each side of the window. There is another method of making the dark chamber, which is by a scioptric ball, that is, a ball of wood, through which a hole is made, in which hole a lens is fixed; this ball is placed in a wooden frame, in which it turns freely round: the frame is fixed to the hole in the shutter, and the ball by turning about answers, in great part, the use of the mirror on the outside of the window: if the hole in the window be no bigger than a pea, the objects will be represented without any lens. If instead of placing the mirror without the window, you place it in the room, and above the hole, (which must then be made near the top of the shutter,) you may receive the representation on a paper placed horizontally on a table; and draw at your leisure all the objects that are there painted. Nothing can be more pleasing than this recreation, especially when the objects are strongly enlightened by the sun; and not only land prospects, but a sea-port, when the water This representation affords the most perfect model for painters, as well for the tone of colours, as that gradation of shades occasioned by the interposition of the air, which has been so justly expressed by some modern painters. It is necessary that the paper have a circular form, for otherwise, when the centre of it was in the focus of the glass, the two sides would be beyond it, and consequently the images would be confused: if the frame were contrived of a spherical figure, and the glass were in its centre, the representation would be still more accurate. If the object without be at the distance of twice the focal length of the glass, the image in the room will be of the same magnitude with the object. The lights, shades, and colours in the camera obscura, appear not only just, but, by the images being reduced to a smaller compass, much stronger than in nature; add to this, that these pictures exceed all others, by representing the motion of the several objects: thus we see the animals walk, run, or fly, the clouds float in the air, the leaves quiver, the waves roll, &c. and all in strict conformity to the laws of nature. The best situation for a dark chamber is directly north, and the best time of the day is noon. To shew the Spots in the Sun’s Disk, by its image in the Camera Obscura. Put the object-glass of a ten or twelve feet telescope into the scioptric ball, and turn it about till it be directly opposite the sun: when the sun is directly opposite the hole, the lens will itself be sufficient; or by means of the mirror on the outside of the window, as in the last recreation, in the focus of the lens, and you will see a clear bright image of the sun, of about an inch diameter, in which the spots on the sun’s surface will be exactly described. As this image is too bright to be seen with pleasure by the naked eye, you may view it through a lens, whose focus is six or eight inches diameter, which, at the same time that it prevents the light from being offensive, will, by magnifying both the image and the spots, make them appear to greater advantage. To magnify small Objects by means of the Sun’s Rays let into a dark Chamber. Let the rays of light that pass through the lens in the shutter be thrown on a large concave mirror, properly fixed To cut a Looking-glass, or piece of Crystal, let it be ever so thick, without the help of a Diamond, in the same shape as the Mark of the Drawing made on it with Ink. This remarkable operation unites utility with amusement; for being in the country, or in a place where there is no glazier to be had, the following means will answer the purpose without their help. Take a bit of walnut-tree, about the thickness of a candle, and cut one of its ends to a point; put that end in the fire, and let it burn till it is quite red: while the stick is burning, draw on the glass or crystal, with ink, the design or outline of the form in which you mean to cut it out: then take a file, or bit of glass, and scratch a little the place where you mean to begin your section; then take the wood red-hot from the fire, and lay the point of it about the twentieth part of an inch, or thickness of a guinea, from the marked place, taking care to blow always on that point, in order to keep it red; following the drawing traced on the glass, leaving, as before, about the twentieth part of an inch interval every time that you present your piece of wood, which you must take care to blow often. After having followed exactly the outlines of your drawing, to separate the two pieces thus cut, you need only pull them up and down, and they will divide. By the means of two plain Looking-glasses, to make a Face appear under different forms. Having placed one of the two glasses horizontally, raise the other to about right angles over the first; and while the two glasses continue in this posture, if you come up to the perpendicular glass, you will set your face quite deformed and imperfect; for it will appear without forehead, eyes, nose, or ears, and nothing will be seen but a mouth and a chin boldly raised: do but incline the glass ever so little from the perpendicular, and your face will appear with all its parts, excepting the eyes and the forehead; stoop a little more, and you will see two noses and four eyes; and then a little further, and you will see three noses and six eyes;—continue to incline If you incline the two glasses, the one towards the other, you will see your face perfect and entire; and by the different inclinations, you will see the representation of your face, upright and inverted, alternately. To know which of two different Waters is the lightest, without any Scales. Take a solid body, the specific gravity of which is less than that of water, deal, or fir-wood, for instance, and put it into each of the two waters, and rest assured that it will sink deeper in the lighter than in the heavier water; and so, by observing the difference of the sinking, you will know which is the lightest water, and consequently the wholesomest for drinking. To know if a suspicious Piece of Money is good or bad. If it be a piece of silver that is not very thick, as a crown, or half a crown, the goodness of which you want to try; take another piece of good silver, of equal balance with it, and tie both pieces with thread or horse hair to the scales of an exact balance, (to avoid the wetting of the scales themselves,) and dip the two pieces thus tied, in water; for then, if they are of equal goodness, that is, of equal purity, they will hang in equilibrio in the water as well as in the air: but if the piece in question is lighter in the water than the other, it is certainly false, that is, there is some other metal mixed with it, that has less specific gravity than silver, such as copper; if it is heavier than the other, it is likewise bad, as being mixed with a metal of greater specific gravity than silver, such as lead. If the piece proposed is very thick, such as that crown of gold which Hiero, king of Syracuse, sent to Archimedes, to know if the goldsmith had put into it all the eighteen pounds of gold that he had given him for that end; take a piece of pure gold of equal weight with the crown proposed, viz. eighteen pounds; and without taking the trouble of weighing them in water, put them into a vessel full of water, one after another, and that which drives out most water, must necessarily be mixed with another metal of less specific gravity than gold, as taking up more space, though of equal weight. To hold a Glass full of Water with the Mouth downwards, so that the Water shall not run out. Take a glass full of water, cover it with a cup that is a little hollow, inverting the cup upon the glass; hold the cup firm in this position with one hand, and the glass with the other; then with a jerk turn the glass and the cup upside down, and so the cup will stand upright, and the glass will be inverted, resting its mouth upon the interior bottom of the cup: this done, you will find that part of the water contained in the glass will run out by the void space between the bottom of the cup, and the brim of the glass; and when that space is filled, so that the water in it reaches the brim of the glass, all passage being then denied to the air, so that it cannot enter the glass, nor succeed in the room of the water, the water remaining in the glass will not fall lower, but continue suspended in the glass. If you would have a little more water descend into the cup, you must, with a pipe or otherwise, draw the water out of the cup, to give passage to the air in the glass; upon which, part of the water will fall into the glass till it has stopped up the passage of the air afresh, in which case no more will come down; or, without sucking out the water in the cup, you may incline the cup and glass so that the water in the cup shall quit one side of the brim of the glass, and so give passage to the air, which will then suffer the water in the glass to descend till the passage is stopped again. This may likewise be resolved by covering the brim of the glass that is full of water, with a leaf of strong paper, and then turn the glass as above; and without holding your hand any longer upon the paper, you will find it as it were glued for some time to the brim of the glass, and during that time the water will be kept in the glass. The Mysterious Watch. Desire any person to lend you his watch, and ask if he thinks it will or will not go when it is laid on the table: if he says it will, place it over the end of a magnet, and it will presently stop; then mark with chalk, or a pencil, the precise point where you placed the watch, and, moving the position of the magnet, give the watch to another person, and desire him to make the experiment; in which he not succeeding, give it to a third person, at the same time replacing the magnet, and he will immediately perform the experiment. To make a Glass of Water appear to boil and sparkle. Take a glass nearly full of water, or other liquor, and setting one hand upon the foot of it to hold it fast, turn How to make a Cork fly out of a Bottle. Put a little chalk or pounded marble into a phial, and pour on some water, with about a third part of sulphuric acid, and put in a cork: in a few seconds, the cork will be sent off with great violence. To produce Gas Light, on a small Scale. Take an ordinary tobacco pipe, and nearly fill the bowl with small coals, and stop the mouth of the bowl with any suitable luting, as pipe-clay, or the mixture of sand and common clay, or, as clay is apt to shrink, of sand and beer, and place the bowl in a fire between the bars of a grate, so that the pipe may stand nearly perpendicular. In a few minutes, if the luting be good, the gas will begin to escape from the stem of the pipe, when, if a piece of lighted paper or candle be applied, it will take fire and burn for several minutes with an intense light. When the light goes out, a residuum of useful products will be found in the bowl. Thunder Powder. Take separately, three parts of good dry saltpetre, two parts of dry salt of tartar, and pound them well together in a mortar; then add thereto one part, or rather more, of flour of brimstone, and take care to pound and mix the whole perfectly together: put this composition into a bottle with a glass stopper, for use. Put about two drams of this mixture in an iron spoon, over a moderate fire, but not in the flame; in a short time it will melt, and go off with an explosion like thunder or a loaded cannon. To tell, by the Dial of a Watch, at what hour any Person intends to rise. Let the person set the hand of the dial to any hour he pleases, and tell you what hour that is, and to the number of Example. Suppose the hour at which he intends to rise be 8, and that he has placed the hand at 5. Then, adding 12 to 5, you bid him call the hour at which the index stands, the number on which he thought; and by reckoning back from this number to 17, it will bring him to 8, the hour required. The following Experiment shews the Power of Attraction. If we take two pieces of lead, as two musket or pistol balls, and with a knife smooth two plane surfaces, and press them together, they will firmly adhere. Two plates of metal made very smooth, when rubbed with oil and put together, will so firmly adhere, that it will require a great force to separate them. If two pieces of wood, or of glass, be wetted with water, and placed together, the one may be lifted up by means of the other. Boys often have a piece of leather on the end of a string, which they wet and put on a stone, and thereby lift it up. If we take a small tube of glass with a narrow bore, and put it in water, the fluid will rise higher within the tube than in the vessel. The narrower the tube is, the higher the water rises. This is called Capillary Attraction. If we put two pieces of glass together, and place the lower edge in water, it will rise between them, as it does in the capillary tubes. This experiment may be made more pleasing, by putting a shilling or a piece of paper between the two pieces of glass at one end. The water will then rise in a curve line, called an hyperbola, higher and higher as it recedes from the shilling or piece of paper, and the pieces of glass get nearer to each other. Place a balance equally poised, so that one scale may be made to touch water in a vessel; considerable weight must be put in the other scale, to make it rise up. Put three or four bits of cork to float in a basin of water; they will gradually draw nearer to each other, and the more rapidly as the distance diminishes. Experiments to shew the Power of Repulsion. Dip a ball in oil and put it in water; a ditch will be formed all round it. Pour water on oiled paper, and it will run off. We may observe that rain water stands in globules on the leaves of cabbages. If we blow up soap-bubbles, and let them fall on the carpet, they will not for some time burst. Let them fall on the table, or any smooth surface, and they will burst instantly. If we pour as much water into a cup as it will possibly hold, we shall see the water above the level of the sides, if the edge be dry, but otherwise we shall not. Lay a very fine needle, or a piece of tinfoil, on the surface of water, and it will float, until it become wet, when it sinks. Lay a piece of gold on mercury, and it will float on the surface; but if depressed below the surface, it will sink to the bottom, like the needle on water. Experiments respecting the Centre of Gravity. The centre of gravity is that part of a body, round which all its parts are so equally balanced, that, if it be supported, the whole body will be so too. Take a book, and find, by trial, under what part the finger must be placed to keep the book from falling; that point is the centre of gravity. Take a rod, or stick, and find that place about the middle of it, under which the finger being placed, it will be balanced; that is the centre of gravity. The moment the centre of gravity ceases to be supported, the whole body falls. Move a piece of board to the edge of a table, and gradually farther and farther off it; the instant the centre of gravity gets beyond the edge of the table, the board falls. Run the point of a knife much slanting into the same board, it may then be brought much farther over the edge of the table than it could before, as the knife, leaning the way of the table, brings the centre of gravity that way. Take a bottle, with a cork in it; stick in the middle of the cork a needle, with the point, upwards; then take another cork, and with a knife make a slit in one of its ends, in which place a shilling so far as to make it fast; then take two forks, or penknives, and stick one on each side the cork, slanting a little downwards; then place the edge of the shilling on the point of the needle, and it will rest secure. It may be made to revolve, with great rapidity, on the point of the needle, without falling off. The following Experiment shews the Power of Steam. Put a little water in a bottle, and cork it securely, covering it with sealing wax; then put the bottle into a kettle of water, and let it boil a short time, and the steam will force out the cork. Diminution of Heat by Evaporation. Pour water on a piece of writing-paper, and hold it over a candle; it will boil without burning the paper. Water may be boiled in an egg-shell on the fire. Experiment to ascertain the Strength of Spirits of Wine. It is a common practice for apothecaries, in order to ascertain if spirit of wine be sufficiently strong, to pour some into a cup upon some gunpowder, and then to set fire to it. If the spirit be sufficiently strong, after burning down to the gunpowder, it will make it go off; but if too much water has been poured in, that will not take place, as, after the spirit is consumed, there will still be water enough to keep the powder wet. To ascertain the Strength of Brine. To ascertain the strength of brine for salting meat, it is usual to put an egg in the boiling water, and gradually put in salt until the egg be made to swim. The following Experiments shew the Pressure and Elasticity of Air. Put an empty bottle with a cork in it near the fire; the cork will be driven out. Get a vessel of hot water, and put a phial into it, with the mouth downwards; the expanded air will bubble out. Let the water cool, or pour cold water on the phial, of which the mouth has not been drawn above the surface of the water, and as the air is now cooled, and occupies less space, a considerable part of the bottle will be filled with water. Boil a little water in a glass phial over a candle for a few minutes; then invert the mouth of the phial in water, and, as it cools, the air will contract, and water will be forced up the bottle, by the external air, to occupy the vacant space. Lay a weighty book on a bladder, and blow into it with a pipe, and the book will be raised. Increase the weight on the bladder very much indeed, and you may still raise it as before. Take a cup, and burn a few pieces of paper in it, the heat will expand the air in it. Invert the cup now in a saucer of water, and, as the enclosed air cools, it will return to its former density, and leave a vacuum, and the pressure of the external air will force a great deal of water up into the cup. If this experiment be performed with a large drinking-glass, the water may be seen to rise in the glass. The pressure of the air may be very sensibly felt, by putting the hole of a common bellows over the knee, and then attempting to raise the upper part of it. Boil water in a glass phial over a candle for a few minutes, then suddenly removing it, tie a piece of wetted bladder over the mouth, making it fast with a string; the pressure of the air will stretch the bladder, if it do not burst it. Get a glass vessel, as a common tumbler, if no better be at hand, and put a piece of wetted bladder over the mouth, pressing it down in the middle, and then tie it firm with a string; then lay hold of the bladder in the middle, and try to pull it straight, or level with the rest, and the pressure of the external air will not permit it. Do exactly the same as before, except that the vessel must be nearly full of water. Turn the vessel upside-down, and the bladder will still continue as it was placed, the pressure of the air overcoming the weight of the water. Though air be capable of compression, it makes a resistance, and that very considerable. The ball of an air-gun has been burst asunder by overcharging it. If bottles are filled too much, they may be burst in attempting to cork them, from the air between the cork and the liquor being too much condensed. Put a common wine-glass, with the mouth downwards, into water; and to whatever depth it may be plunged, the air will not allow much water to rise into it, as may be seen by the inside of the glass not being wet. If a bit of cork float inside of the glass, it will point out to the eye still more clearly how high the water rises. This experiment, though so very simple will illustrate the nature of the diving-bell. Experiments respecting Sound. Hold a tumbler sideways, and sprinkle a little dust, or powder of any sort, on it; then strike the glass, and make it sound:—the dust keeps dancing about whilst the sound continues; stop the sound, and the dust is at rest. The sound of a watch laid upon a long table, or upon a When a vessel on the fire begins to boil, let a communication be made between it and the ear, by means of the poker, and the sound is more distinctly heard. Tie a string round the end of a poker, and then, winding one end of the string round the fore-finger of the one hand, and the other end of the string round the fore-finger of the other; put the fingers into the ears, and make the poker strike against a table, or any other object, and it will sound like the bell of a church. Tie a string round the end of a poker, as before, and hold the string with your teeth; when the poker is made to strike against any object, as in the last experiment, the same kind of sound will be transmitted through the teeth. Make a watch touch your teeth, and you will hear its beating more distinctly. When a pitchfork is struck, in order to pitch a tune, its end is put on the table, and a greater sound is produced. If the pitchfork, after being struck, be held to the teeth, its sound is still more distinct. Having shut up both ears with cotton very closely, put your fingers on the teeth of a person who speaks to you, and you will hear his voice. Electrical Experiments. If a piece of sealing-wax be rubbed briskly against the sleeve of your coat, or any other woollen substance, for some time, and then held within an inch or less of hair, feathers, bits of paper, or other light bodies; they will be attracted, that is, they will jump up, and adhere to the wax. If a tube of glass, or small phial, be rubbed in a similar manner, it will answer much better. The bottle thus rubbed becomes electric; and when the operation is performed in a dark room, small flashes of divergent flame, ramified somewhat like trees bare of leaves, will dart into the air, from many parts of the surface of the tube, to the distance of six or eight inches, attended with a crackling noise; and sometimes sparks will fly along the tube to the rubber at more than a foot distant. Cut two bits of cork into the shape and size of a common pea. With a needle, draw a thread through each of the corks, so that they may be made to hang at the ends of the threads with a knot below them. Let the other ends of the threads be inserted in the notch of a small piece of wood, about a foot long, and an inch broad, and the thickness of a common match. Lay the piece of wood over two wine-glasses, a few inches asunder, so that the end of it, in which the threads Lay a pocket-watch upon a table, and take a common tobacco-pipe, and place it on the face of the watch so that it may balance thereon; then, after rubbing a wine-glass, as described in the former experiment, bring it to within an inch of the smaller end of the tobacco-pipe, and by moving the glass gently round in an horizontal circular track, you will cause the pipe to turn round on the watch-glass, as the needle turns on its centre in a mariner’s compass. A curious Experiment made by Mr. Symmer, on the Electricity of Silk Stockings. This gentleman having frequently observed, that on putting off his stockings in the evening, they made a crackling or snapping noise, and that in the dark they emitted sparks of fire, was induced to examine on what circumstances these electrical appearances depended. After a considerable number of observations, directed to this point, he found that it was the combination of white and black which produced the electricity, and that the appearances were the strongest when he wore a white and a black stocking upon the same leg. These, however, discovered no signs of electricity while they were upon the leg, though they were drawn backwards and forwards upon it several times; but the moment they were separated, they were both of them found to be highly electrified, the white positively, and the black negatively; and when they were held at a distance from each other, they appeared inflated to such a degree, that they exhibited the entire shape of the leg. When two black or two white stockings were held together, they would repel one another to a considerable distance; and when a white and black stocking were presented to each other, they would be mutually attracted, and rush together with great violence, joining as close as if they had been so many folds of silk; and in this case their electricity did not seem to have been in the least impaired by the shock of meeting, for they would be again inflated, attract, repel, and rush together, as before. When this experiment was performed with two black stockings in one hand, and two white ones in the other, it exhibited a still more curious spectacle. The repulsion of those of the same colour, and the attraction of those of different colours, What was also very remarkable in these experiments with a white and black stocking, was, the power of electrical cohesion which they exhibited; Mr. Symmer having found, that when they were electrified, and allowed to come together, they frequently stuck so close to each other, that it required a weight of sixteen or seventeen ounces to separate them, and this in a direction parallel to their surfaces. When one of the stockings was turned inside-out, it required twenty ounces to separate them; and by having the black stockings new dyed, and the white ones washed, and whitened in the fumes of sulphur, and then putting them one within the other, it required three pounds three ounces to separate them. Trying this experiment with stockings of a more substantial make, he found that, when the white stocking was put within the black one, so that its outside was contiguous to the inside of the other, they raised near nine pounds; and when the white stocking was turned inside-out, and put within the black one, so that their rough surfaces were contiguous, they raised fifteen pounds, which was ninety-two times the weight of the stockings. And, in all these cases, he found that pressing them together with his hands contributed much to strengthen the cohesion. When the white and black stockings were in cohesion, and another pair, more highly electrified, were separated from each other, and presented to the former, their cohesion would be dissolved, and each stocking of the second pair would catch hold of, and carry away with it, that of its opposite co-lour; but if the degree of electricity of both pairs were equal, the cohesion of the former would be weakened, but not dissolved, and all the four would cohere together in one mass. Mr. Symmer also observed, that white and black silk, when electrified, not only cohered with each other, but they would also adhere to bodies with broad, and even polished, surfaces, though those bodies were not electrified. This he discovered, by throwing accidentally a stocking out of his hand, which stuck to the paper-hangings of the room, and which, in another experiment of this kind, continued hanging there nearly an hour. Having stuck up the black and white stockings in this manner, he came with another pair of stockings, highly electrified, and applying the white to the black, and the black to the white, he carried them off from the wall, each of them hanging to that which had been brought to it. The same experiment also held with the painted boards of the room, and likewise with the looking-glass, to the smooth surface of To suspend a Ring by a Thread that has been burnt. The thread having been previously soaked in chamber lye, or common salt and water, tie it to a ring, not larger than wedding-ring. When you apply the flame of a candle to it, though the thread burn to ashes, it will yet sustain the ring. Chemical Illuminations. Put into a middling-sized bottle, with a short wide neck, three ounces of oil or spirit of vitriol, with twelve ounces of common water, and throw into it, at different times, an ounce or two of iron filings. A violent commotion will then take place, and white vapours will arise from the mixture. If a taper be held to the mouth of the bottle, these vapours will inflame, and produce a violent explosion; which may be repeated as long as the vapours continue. To make the Appearance of a Flash of Lightning when any one enters a Room with a lighted Candle. Dissolve camphor in spirit of wine, and deposit the vessel containing the solution in a very close room, where the spirit of wine must be made to evaporate by strong and speedy boiling. If any one then enters the room with a lighted candle, the air will inflame; but the combustion will be so sudden, and of so short duration, as to occasion no danger. The Fiery Fountain. If twenty grains of phosphorus, cut very small, and mixed with forty grains of powdered zinc, be put into four drachms of water, and two drachms of concentrated sulphuric acid be added thereto, bubbles of inflamed phosphuretted hydrogen gas will quickly cover the whole surface of the fluid in succession, forming a real fountain of fire. A Lamp that will burn Twelve Months without replenishing. Take a stick of phosphorus, and put it into a large dry phial, not corked, and it will afford a light sufficient to discern any object in a room, when held near it. The phial should be kept in a cool place, where there is no great current of air, and it will continue its luminous appearance for more than twelve months. The Magic Oracle. Get six blank cards, and write on them figures, or numbers, exactly according to the following patterns. No. I
No. II.
No. III.
No. IV.
No. V.
No. VI.
You deliver the cards to a person, and desire him to think of any number from one to sixty; he is then to look at the cards, and say in which cards the number he thought of is to be found; and you immediately tell him the number thought of. This surprising and ingenious recreation is done by means of a key number. There is a key number in every card, viz. the last but one in the second row from the top. From this explanation the reader will perceive that the key numbers are 1, 2, 4, 8, 16, 32. Now whatever number is fixed on, from 1 to 60, will be readily found by privately adding together the key numbers of the cards that contain the number thought on. For instance, suppose a person thinks of number 43; he looks at the cards, and gives you No. 1, 2, 4, 5, 6, as cards which contain the number thought on: you expertly perceive that the key numbers are 1, 2, 8, 32; which numbers added together make 43, the number thought on. Suppose he thinks of No. 15, he gives you No. 1, 2, 3, 4: the key numbers are 1, 2, 4, 8; which added, make just 15; and so of all numbers from 1 to 60. This recreation may be varied many ways; as, telling the age of a person, &c.; but this is left to the ingenious reader’s taste and application. Cheap and Easy Method of constructing a Voltaic Pile. Mr. Mitchell, in his useful little work on natural philosophy, proposes the following cheap and easy method of constructing a Voltaic Pile. Zinc is one of the cheapest of metals, and may be easily melted, like lead. Let the student cast twenty or thirty pieces, of the size of a penny-piece, which may easily be done in moulds made in clay. Let him then get as many penny-pieces, and as many pieces of paper, or cloth cut in the same shape, and these he must dip in a solution of salt and water. In building the pile, let him place a piece of zinc, wet paper, (the superabundant water being squeezed out,) after which the copper; then zinc, paper, copper, &c. until the whole be finished. The sides of the pile may be supported with rods of glass, or varnished wood, fixed in the board on which it is built. The following experiment may then be performed:— Having wetted both hands, touch the lower part of the pile with one hand, and the upper part with the other, constant, little shocks of electricity will be felt until one hand be removed. If the hand be brought back, a similar repetition of shocks will be felt. Put a basin of water near the pile, and put the left hand into it, holding a wire, one end of which touches the top of the battery or pile; then put the end of a silver spoon between the lip and the gum, and with the other end of the spoon touch the lower part of the pile; a strong shock is felt in the gum and in the hand. Take the left hand from the water, but still keep hold of the wire, and then In performing the above experiments, if, instead of the two ends of the pile, the one end and the middle of it be touched, the sensations will not be nearly so strong. If the student be desirous of having still more sensible proofs of the effect of galvanism, let him hold a wire to the top of the battery, and let him place one end of a silver spoon to the lower part, and the other end within his mouth, so as to touch the gums; a severe set of shocks will be felt. In performing this experiment, move the spoon to the roof of the mouth, and a strong sensation will be felt. Let the end of the spoon be run up the nose so as to touch the cartilaginous bone; shocks like the stabs of a needle will be felt. Let the end of the spoon be put under the eye-brow, close to the ball of the eye; a sensation will be felt like the burning of red-hot iron, but which ceases the instant the spoon is removed. Magnetical Experiments. The magnetic attraction will not be destroyed by interposing obstacles between the magnet and the iron. Lay a small needle on a piece of paper, and put a magnet under the paper; the needle may be moved backwards and forwards. Lay the needle on a piece of glass, and put the magnet under the glass; it will still attract the needle. The same effects will take place if a board be interposed between the magnet and the iron. This property of the magnet has afforded the means of some very amusing deceptions. A little figure of a man has been made to spell a person’s name. The hand, in which was a piece of iron, rested on a board, under which a person, concealed from view, with a powerful magnet, contrived to carry it from letter to letter, until the word was made up. The figure of a goose or swan, with a piece of iron concealed about the head, is set to float in water. A rod, with a concealed magnet at the end, is presented to the bird, and it swims after it. The effect is still more amusing, when some food is put on the end of the rod. The figure of a fish is thrown into the water, with a small magnet concealed in its mouth. Of course, if a baited hook be suspended near it, the magnet and iron, by mutual attraction, will bring the fish to the bait. Put a piece of iron in one scale of a balance, and an equal If a magnet suspended by one string, and a piece of iron suspended by another, be brought near one another, they will mutually attract each other, and be drawn to a point between. Suspend a magnet nicely poised by a thread, and it will point north and south, the same end pointing invariably the same way. Rub a fine needle with a magnet, and lay it gently on the surface of the water; it will point north and south. Rub various needles with the magnet, and run them through small pieces of cork, and put them to swim in water; they will all point north and south, and the same end will invariably point the same way. This mode of finding the north is sometimes of the utmost service at sea, when the compass is destroyed. Opposite poles attract; poles of the same name repel. Take two magnets, or two needles rubbed with the magnet, and bring the north and south poles together, and they attract. Bring the north poles near each other, and they repel. Bring the south poles near each other, and they repel. Rub a needle with a magnet, and run it through a piece of cork, and put it to float in water. Hold a north pole of a magnet near its north pole, and it will keep flying away to avoid it. It may be chased from side to side of a basin. On the other hand, an opposite pole will immediately attract. Rub four or five needles, and you may lift them up as in a string, the north pole of one needle adhering to the south pole of another. Put a magnet under a piece of glass, and sprinkle iron-filings on it; they will arrange themselves in a manner that will be very surprising. At each pole will be a vast abundance standing erect, and there will be fewer and fewer as they recede, until there are scarcely any in the middle. If the iron-filings are sprinkled on the magnet itself, they will arrange themselves in a manner very striking. Lay a needle exactly between the north and south pole, it will move towards neither. Artificial Coruscations. There is a method of producing artificial coruscations, or sparkling fiery meteors, which will be visible not only in the To make an Egg enter a Phial without breaking. Let the neck of a phial be ever so strait, an egg will go into it without breaking, if it be first steeped in very strong vinegar, for in process of time the vinegar does so soften it, that the shell will bend and extend lengthways without breaking: and when it is in, cold water thrown upon it will recover its primitive hardness, and, as Cardan says, its primitive figure. Light produced by Friction, even under Water. Rub two pieces of fine lump sugar together in the dark; the effect is produced, but in a much greater degree, by two pieces of silex, or quartz: but that which affords the strongest light of any thing, is a white quartz[25] from the Land’s End, Rosin Bubbles. The following account of a simple and curious experiment is extracted from a letter written by Mr. Morey, of Oxford, New Hampshire, to Dr. Silliman, the editor of the American Journal of Science and Arts. “If the end of a copper tube, or of a tobacco-pipe stem, be dipped in melted rosin, at a temperature a little above that of boiling water, taken out and held nearly in a vertical position, and blown through, bubbles will be formed of all possible sizes, from that of a hen’s egg down to sizes which can hardly be discerned by the naked eye; and from their silvery lustre, and reflection of the different rays of light, they have a pleasing appearance. Some that have been formed these eight months, are as perfect as when first made. They generally assume the form of a string of beads, many of them perfectly regular, and connected by a very fine fibre; but the production is never twice alike. If expanded by hydrogen gas, they would probably occupy the upper part of the room. “The formation of these bubbles is ascribed to a common cause, viz. the distention of a viscous fluid by one that is aËriform; and their permanency, to the sudden congelation of the rosin thus imprisoning the air by a thin film of solid matter, and preventing its escape.” A curious Hydraulic Experiment, called the Magical Bottle. Take a small bottle, (see Plate) AB, Fig. 9, the neck of which must be very narrow, and provide a glass vessel, CD, the height of which exceeds that of the bottle about two inches; fill the bottle, by means of a small funnel, with red wine, and place it in the vessel CD, which is to be previously filled with water. Then, if the bottle be uncorked, the wine will presently come out of it, and rise in form of a small column, to the surface of the water; and at the same time the water entering the bottle, will supply the place of wine; for water being specifically heavier than wine, it will consequently subside to the lowest place, while the other naturally rises to the top. A similar effect will be produced, if the bottle be filled with water, and the vessel with wine, for the bottle being placed Another Hydraulic Experiment, called the Miraculous Vessel. Take a tin vessel of about six inches in height, and three in diameter, having a mouth of only a quarter of an inch wide, and in the bottom of the vessel make a number of small holes, of a size sufficient to admit a common sewing needle. Plunge the vessel into water, with its mouth open, and when it is full, cork it, and take it out again; then, as long as the vessel remains corked, no water will come out of it; but as soon as it is uncorked, the water will immediately issue from the small holes at the bottom. It must be observed, however, that if the holes at the bottom of the vessel be more than one-sixth of an inch in diameter, or if they be too numerous, the experiment will not succeed; for, in this case, the pressure of the air against the bottom of the vessel will not be sufficient to confine the water. A curious Hydraulic Experiment, called Tantalus’s Cup. Take a glass, or any other vessel, (see Plate) ABCD, fig. 10. which has a small bent pipe, EFG, open at each end, running through the middle of it; then, if water or wine be poured into the glass, it will continue in it till the tube is full up to the bend F, which should be a little lower than the upper edge of the glass; but if, after this, you continue to pour more liquor into it, it will endeavour, as usual, to rise higher in the glass, but not finding room for a farther ascent in the tube, it will descend through the part EG, and run out at the end G, as long as you continue to put it in. To those who are unacquainted with the nature of the syphon, the effect may perhaps appear something more extraordinary, if the longest branch of the tube be concealed in the handle of the cup. This is called the cup of Tantalus, from its resemblance to an experiment of the same kind, by placing an upright image in the cup, and disposing the syphon in such a manner, that, as soon as the water rises to the chin of the image, it will begin to run out through the longest leg, in the same manner as from the cup above-mentioned. A curious Chemical Experiment, called the Tree of Diana. Make an amalgam, without heat, of two drachms of leaf silver with one drachm of quicksilver. Dissolve this amalgam A metallic arborisation, somewhat similar, may be produced in the following manner:—Dissolve a little sugar of lead in water, and fill a phial with the solution. Pass a wire through the cork, and affix to the upper part of the wire a small bit of silver, or zinc, in such a manner that it may be immersed in the solution not far from its surface. Set the phial in some place where it may remain undisturbed, and in about twenty-four hours you will perceive the lead beginning to shoot round the wire: this process will continue going on slowly, till you have a beautiful metallic tree. If you have a wide-mouthed phial, or glass jar, the experiment may be pleasingly diversified, by arranging the wire in various forms. A remarkable Experiment, called Prince Rupert’s Drops. Take up a small quantity of the melted matter of glass with a tube, and let a drop of it fall into a vessel of water. This drop will have a small tail, which, being broken, the whole substance of the drop will burst, with great violence, into a fine powder, and give a little pain to the hand, but do no hurt to it. It is a remarkable circumstance in this experiment, that the bulb, or body, will bear the stroke of a hammer, without breaking; but when the tail is broken, the above-mentioned effect is produced. If the drop be cooled in the air, the same effect will not take place; and if it be ground away on a stone, nothing extraordinary appears; but if it be put into the receiver of an air-pump, and then broken, the effect will be so violent as to produce light. How to make Sympathetic Inks of various Kinds. By sympathetic inks, are meant those kinds of liquors, with which if any characters be written, they will remain invisible, till some method is used to give them a colour. The first class of these inks consists of such as become visible by passing another liquor over them, or by exposing them to the vapour of that liquor. The third, of such as become apparent by strewing or sifting some very fine powder over them. The fourth, of those which do not become visible till they are exposed to the fire, or heated. The fifth, like the fourth, of such as appear by heat, but disappear again when the paper becomes cold, or has had a sufficient time to imbibe the moisture of the air. Sympathetic Inks of the First Class.—Put some litharge into strong distilled vinegar, and let it stand for twenty-four hours; then strain it off, and, after it is quite settled, put it into a bottle closely corked, and preserve it for use. Having done this, put into a pint bottle two ounces of quicklime, one ounce of orpiment in powder, and as much water as will rise two or three fingers’ breadth above them; and when the solution is made, pour the liquid gently off, and let it stand in the sun for two or three days, observing to turn it five or six times each day. When these liquors are ready for use, any letters written by the first, being exposed to the vapours of the second, will quickly become visible; and if you would have them disappear again, you must draw a sponge, or pencil, dipt in aqua-fortis, or spirit of nitre, over them: and if, after this, you would have them appear again, stay till the paper is quite dry, and then pass the vivifying liquor, made of the solution of orpiment, over them, as before. Another Ink of this Class.—Dissolve bismuth in the nitrous acid, and any letters written with this ink will become quite black, by being exposed to the vapour of liver of sulphur, which is of so penetrating a nature, that it will act upon the ink through a quire of paper, or even the slight partition of a room. A Sympathetic Gold Ink of the Second Class.—Put as much gold into a small quantity of aqua-regia as will dissolve it, and then dilute it with two or three times as much distilled water. Also dissolve, in a separate vessel, fine pewter in aqua-regia; and when it is well saturated, add to it an equal quantity of distilled water. Then, if any characters be written with the solution of gold, put them in the shade till they become quite dry, and they will not appear for the first seven or eight hours, but if you dip a pencil, or small fine sponge, in the solution of pewter, and draw it lightly over the invisible characters, they will presently appear of a purple colour. The purple colour of these letters may be effaced again, by A Sympathetic Ink of the Second Class.—Dissolve fine silver in aqua-fortis, and add some distilled water to the solution, in the same manner as in the gold ink; then, whatever is written with this ink, will remain invisible for three or four months, if it be kept close from the air; but if it be exposed to the sun, it will appear in about an hour, of a gray colour, like that of a slate. Sympathetic Inks of the Third Class,—or such as become visible by having any fine powder strewed over them,—may be composed of the glutinous and colourless juice of any vegetable, the milk of animals, and several other substances. Sympathetic Inks of the Fourth Class,—are made by diluting acid of vitriol with about three times its weight of common water, or as much as will prevent it from corroding the paper. The juice of lemons, or onions, will answer the same purpose; but either of them requires more heat than the first, and will not keep so long. A Green Ink of the Fifth Class.—Take zaffre in powder, and let it remain dissolved in aqua-regia for twenty-four hours; after which pour the liquor off clear, and, adding to it as much common water, keep it in a bottle well corked. Then, if any characters be written with this ink, and exposed to the fire, or strong rays of the sun, they will appear of a lively green. It is the peculiar property of this ink, that as soon as the paper becomes cold again, the letters will disappear; and this alternate appearance and disappearance may be repeated a great number of times, provided the heat be not too great. Other Sympathetic Inks. A Yellow Ink of this kind may be made, by steeping the flowers of marigolds seven or eight days in clear distilled vinegar, and then pressing them out, and keeping the liquor well corked in a bottle for use. For a Red invisible Ink,—take the pure spirit of vitriol, or that of nitre, and add to it eight or ten times as much water, according as you would have it more or less red. For a Green Ink of this sort,—dissolve salt of tartar, the clearest and driest you can procure, in a sufficient quantity of river water; and for a Violet sympathetic Ink, express the juice of lemons, and keep it in a bottle well corked. Then, if any characters be written with one of these inks, they will appear in their proper colours, the paper having been dipped in the following liquor. Take a sufficient quantity of the flowers of pansies, or A Sympathetic Ink which appears by being wetted with Water. Mix alum with a sufficient quantity of lemon juice; then, if any letters or characters be written with this mixture, they will be invisible till they are wetted with water, which will make them appear of a grayish colour, and quite transparent. Or, you may write with a strong solution of roch-alum only, and when the writing is dry, pour a small quantity of water over it, and it will appear of a white colour, like that of the paper before it was wetted. Also all saline liquors, such as vitriolic, nitrous, and marine acids, diluted with water, the liquor of fixed vegetable alkalis, and even vinegar, will produce the same effect. If a little aqua-fortis be mixed with the water, the writing will dry well, and not run out of its form when the paper is wetted. A curious Recreation with Sympathetic Ink, called the Book of Fate. Make a book, consisting of seventy or eighty leaves, and in the cover at the end of it, let there be a case which opens next to the back, that it may not be perceived. At the top of each right-hand page, write any question you please; and at the beginning of the book, let there be a table of those questions, with the number of the pages in which each is to be found. Then write with common ink on separate papers, each about half the size of the pages, the same questions that are in the book; and under each of them, write the answer with the ink made with the litharge of lead, or the solution of bismuth. Soak a double paper in the vivifying ink, made of quicklime and orpiment, or the liver of sulphur; and just before you make the experiment, place it in the case that is in the cover of the book. Having done this, deliver some of the papers on which the questions are written, to the company; and after they have chosen such as they wish to have answered, let them put them into those leaves where the same questions are contained; then shutting the book for a few minutes, the sulphureous spirit, with which the paper in the cover of the book is impregnated, will penetrate the leaves, and make the answer visible, which will be of a brown colour, and more or less deep, in proportion to the time the book has been closed. A curious Recreation, called the Transcolorated Writing. Write on a paper, with a violet-coloured liquor, as many letters or words as you please, and ask any person which he will choose to have the writing,—yellow, green, or red. When he has made his choice, have a sponge ready with three sides, which you can easily distinguish, and dip each of its sides in one of the three sympathetic inks; then draw the side of the sponge which corresponds to the colour the person has chosen, over the writing, once only, and it will directly change to the colour required. An Experiment with Sympathetic Ink, called the Oracular Letters. Write on several slips of paper different questions, and such as may be answered by the name of some person: for example, Who is the merriest man in company?—Answer, Mr. * * *. To whom will Miss * * * be married?—Answer, To Mr. * * *. These questions are to be written in the sympathetic ink of the fourth class, and exposed to the fire, and the answers written in the same ink, and left invisible. The papers are then to be folded in the form of letters, and in such a manner, that the part where the name is written shall be directly under the seal; in which case, the heat of the wax will make it visible. Then, if the letter be given to the person who requires the answer, he will find it plainly written. An Experiment with Sympathetic Ink, called Winter changed to Spring. Take a print which represents winter, and trace over the trees, plants, and ground, with the green sympathetic ink; observing to make some parts deeper than others, according to their distance. When those parts are dry, paint the other objects in their natural colours; then put the print into a glazed frame, and cover the back of it with a paper, pasted over its border only. When this print is exposed to the heat of a moderate fire, or to the warm rays of the sun, all the grass and foliage will turn to a pleasing green; and if a yellow tint be given to some parts of the print, before the sympathetic ink be drawn over it, the green will be of different shades, and the scene, that a minute before represented Winter, will now be changed into Spring. When this print is placed in the cold, Winter will appear again, and be again driven away by the warm rays of the sun; and this alternate change of seasons may be repeated as often as you please, provided the print be not made too hot. A remarkable Experiment, called the Revivified Rose. Take a rose that is quite faded, and throw in some common sulphur in a chafing-dish of hot coal. Hold the rose over the fumes, and it will become quite white; then dip it into a basin of water, and giving it to any one, tell him to put it into his box or drawer, and after locking it, to give you the key. About five or six hours afterwards, return him the key, and when he unlocks his drawer, instead of the white rose he put into it, he will find one perfectly red. How to Write on Glass by means of the Rays of the Sun. Dissolve chalk in aqua-fortis, to the consistence of milk, and add to it a strong solution of silver; keep this liquor in a glass decanter, well stopped, and cutting out from a paper the letters you wish to appear, paste it on the decanter, and place it in the sun, in such a manner, that its rays may pass through the spaces cut out of the paper, and fall on the surface of the liquor; then will that part of the glass through which the rays pass be turned black, while that under the paper will remain white; but particular care must be taken that the bottle be not moved during the time of the operation. To produce different Colours, by pouring a colourless Liquor into a clean Glass. Take a strong solution of quicksilver, made with spirit of nitre; dilute it with water, and pour it into a hot glass, rinsed in strong spirit of sea-salt, and it will instantly become coloured. Or, if a solution of silver, made with spirit of nitre, considerably diluted, be poured into a glass, prepared in the manner above-mentioned, it will produce the same effect. And if you pour hot water upon new-made crocus metallorum, and put it into a clean glass, rinsed with any acid, it will produce an orange colour. To produce a Colour which appears and disappears by the Influence of the Air. Put into a decanter some volatile spirit, in which you have dissolved copper filings, and you will have a fine blue tincture; and if the bottle be stopped, the colour will soon return again; and this experiment may be repeated a considerable number of times. To turn a colourless Liquor Black, by adding a White Powder to it. Put a hot weak pellucid infusion of galls into a glass, and throw into it a grain of the vitriol of iron, calcined to whiteness, and considerably heated; then, as it falls to the bottom, it will make a black cloud, which will uniformly diffuse itself through the transparent liquor, and gradually turn it black. The same effect may also be produced by the addition of a little vitriol of iron calcined to a yellow colour, or by the colcothar of vitriol calcined to redness. The black liquor, produced as above, may be rendered pellucid again, by pouring the liquor hot into a glass rinsed with the pure acid of vitriol. And to make this transparent liquor black again, pour to it as much hot oil of tartar per deliquium as will saturate the acid, which has attracted the metallic matter. Freezing Mixture. In the time of snow, a freezing mixture may easily be made, by mixing a little snow and common salt in a basin near the fire. If water in an iron cup or phial be put into this mixture, it will immediately be frozen; and if pounded ice and common salt be added, it will have a still more powerful effect. Experiments with the Microscope. They who possess this amusing instrument, may easily perform with it a variety of pleasing experiments; among others, the following:—Leave some vinegar exposed in a saucer, for a few days, to the open air; then place a drop of it, by means of a clean pen, or a camel’s hair brush, on the transparent object-plate of the microscope; and if the object-plate be properly illuminated from below, you will observe in this drop of liquor animals resembling some small eels, which are in continual motion. If you slightly bruise some pepper-corns, and infuse them in water for a few days, and then expose a drop of it to the microscope, a number of animals of a different kind will be visible. These are of an oblong shape, and, like the others, in continual motion, going backwards and forwards in all directions, turning aside when they meet each other, or when their passage is stopped by some obstacle. In other infusions, as in that of new hay, differently shaped animalcules will be found. When the drop in which they swim, and which to them is like a pond, becomes diminished by evaporation, they gradually retire towards the middle, It the smallest quantity or drop of sulphuric acid be put into a drop of the infusion which swarms with these insects, they immediately throw themselves on their backs, and expire; sometimes losing their skin, which bursts, and suffers small particles of air to escape. Those who wish to be furnished with microscopic eels, at all seasons, may have them in common paste, such as the bookbinders commonly use. It should neither be too stiff, nor too watery. Expose it to the air, and prevent its hardening or becoming mouldy on the surface, by beating it well together, when it has that tendency. After some days it will become sour; and then, if examined attentively by a microscope, multitudes of exceedingly small, long, and slender animalcules will be visible; these will grow larger, till they are of sufficient size to be seen by the naked eye. A drop or two of vinegar should now and then be poured on the paste; and sometimes, to prevent its being dry, a little vinegar and water. By this means microscopic eels may be had all the year. They must be applied to the microscope upon any flat surface, after having first put on it a very small drop of water for them to swim in. These are very entertaining objects when examined by any kind of microscope, but particularly the solar one, by which the motions of their intestines may very plainly be distinguished; and when the water is nearly dried away, and they are on the point of expiring, their mouths may be seen opening to a considerable width. If some of the dust of the puff-ball be examined with the microscope, it appears to consist of perfectly round globules, of an orange colour, the diameter of which is only about the one-fiftieth part of the thickness of a hair, so that each of this grain is but the 1/125000th part of a globule, equal in diameter to the breadth of a hair. The farina of flowers is found to be regularly or uniformly organized in each kind of plant. In the mallow, for example, each grain is an opaque ball, covered over with small points. The farina of the tulip, and of most of the liliaceous kind of flowers, bears a striking resemblance to the seeds of the cucumber: that of the poppy is like grains of barley. There are certain plants, the leaves of which seem to be pierced with a multitude of small holes. Of this kind is the St. John’s Wort. If a fragment of this be viewed with a good microscope, the supposed holes are found to be vesicles, contained in the thickness of the leaf, and covered with an exceedingly thin membrane; and these are thought to be the There are two kinds of sand, viz. the calcareous and the vitreous: the former, examined with a microscope, resembles large irregular fragments of rock; but the latter appears like so many rough diamonds. In some instances, the particles of sand seem to be highly polished and brilliant, like an assemblage of diamonds, rubies, and emeralds. Charcoal is a fine object for the microscope: it is found to be full of pores, regularly arranged, and passing through its whole length. Those who wish to observe the circulation of the blood, by means of the microscope, may readily obtain the desired satisfaction. An object employed chiefly for this purpose is the delicate transparent membrane which unites the toes of the frog; another object is the tail of the tadpole. If this membrane be extended, and fixed on a piece of glass illuminated below, the motion of the blood in the vessels will be distinctly visible; the appearance resembles a number of small islands, with a rapid current flowing between them. Take a small tadpole, and, having wrapped its body in a piece of moist cloth, place its tail on the object-plate of the microscope, and enlighten it below, and you will see very distinctly the circulation of the blood; which in some of the vessels proceeds by a kind of undulation, and in others with a uniform motion. The former are thought to be the arteries in which the blood moves, in consequence of the alternate pulsation of the heart; the latter are said to be the veins. The circulation of the blood may be seen also in the legs and tails of shrimps. The transparent legs of small spiders, and those of bugs, will also afford the means of observing the circulation of the blood to very great advantage. The latter are said, by Mr. Baker, to exhibit an extraordinary vibration of the vessels, which he never saw any where else. Very small fish are good objects for this purpose; but the most curious of all spectacles of this kind, is that exhibited by the mosentery of a living frog, applied in particular to the solar microscope. If you take off a small piece of the epidermis, or scarf skin, of the hand, by means of a sharp razor, and place it on the object-plate of the microscope, you will see it covered with a The hairs of animals, seen through a microscope, appear to be organized bodies: they are composed of long, slender, hollow tubes; some seem to be composed of several small hairs, covered with a common bark; others are hollow throughout. The bristles of a cat’s whisker, when cut transversely, exhibit the appearance of a medullary part, which occupies the middle, like the pith in the twig of the elder-tree. A human hair, cut in the same manner, shews a variety of vessels in very regular figures. Hair taken from the head, the eyebrows, the nostrils, the beard, the hand, &c. appear unlike, as well in the roots as in the hairs themselves, and vary as plants do of the same genus, but of different species. Those of the hedgehog contain a kind of real marrow, which is whitish, and formed of radii meeting in a centre. A split hair appears like a stick shivered with beating. Nothing can be more curious than the appearance exhibited by mouldiness, when viewed through a microscope. If looked at by the naked eye, it seems nothing but an irregular tissue of filaments; but the magnifying-glass shews it to be a forest of small plants, which derive their nourishment from the moist substance which serves them as a base. The stems of these plants may be plainly distinguished, and sometimes their buds, some shut, and some open. They have much similarity to mushrooms, the tops of which, when they come to maturity, emit an exceedingly fine dust, which is their seed. Upon examining the edge of a very keen razor with a microscope, it will appear as broad as the back of a thick knife, rough, uneven, full of notches and furrows. An exceedingly small needle resembles a rough iron bar. But the sting of a bee, A small piece of exceedingly fine lawn, appears, through a microscope, like a hurdle or lattice, and the threads themselves seem coarser than the yarn with which ropes are made for anchors. But a silkworm’s web appears perfectly smooth and shining, and every where equal. The smallest dot that can be made with a pen, appears, when viewed by the microscope, an irregular spot, rough, jagged, and uneven. But the little specks on the wings or bodies of insects, are found to be most accurately circular. A microscope will prove the most boasted performances of art to be ill-shaped, rugged, and uneven. The finest miniature paintings appear before this instrument as mere daubings, plastered on with a trowel, entirely void of beauty, either in the drawing or the colouring. The most even and beautiful varnishes and polishings will be found to be mere roughness, full of gaps and flaws. Thus sink the works of art, before the microscopic eye. But the nearer we examine the works of God, even in the least of his productions, the more sensible shall we be of his wisdom and power. Apply the microscope to any, the most minute of his works, nothing is to be found but beauty and perfection. If we examine the numberless species of insects that swim, creep, or fly around us, what proportion, exactness, uniformity, and symmetry, shall we perceive in all their organs! what a profusion of colouring! azure, green, and vermilion, gold, silver, pearls, rubies, and diamonds; fringe and embroidery on their bodies, wings, heads, and every other part! how high the finishing, how inimitable the polish, we every where behold! Their wings, all glorious to behold! The most perfect works of art betray a meanness, a poverty, an inability in the workman; but the works of nature plainly prove, that “the hand which formed them was divine.” Amusing Experiments with the Thermometer. A thermometer is amusing in a room, to enable us to know with accuracy the real degree of heat, as our own feelings are so very deceptive. According to their state of health at the time, different persons will give a different judgment on the subject. After hot weather, a day which is not very cold, will yet feel so to us, and after cold weather we shall be ready to think a day warm, which is not so severe as the preceding. Experiments will shew how differently the feelings of different individuals may be affected by the same degree of heat. Let one person go out into the cold air in winter for a few minutes, and let another sit by a warm fire; then introduce both into a room without a fire: the person from the cold will feel it warm, and the other will feel it cold. A much more entertaining experiment will shew, that what will be cold to the one hand, will be warm to the other. Pour warm water into one basin, cold water into a second, and a mixture of hot and cold water into a third; then put the one hand into the cold water, and the other into the warm, for two minutes, and after that put both hands into the lukewarm water, and to the one hand it will feel cold, and to the other hot. The Barometer. Rules for judging of and predicting the State of the Weather by the Barometer. The rising of the mercury presages, in general, fair weather, and its falling, foul weather, as rain, snow, high winds, and storms. When the surface of the mercury is convex, or stands higher in the middle than at the sides, it is a sign the mercury is then in a rising state; but if the surface be concave, or hollow in the middle, it is then sinking. In very hot weather, the falling of the mercury indicates thunder. In winter, the rising presages frost; and in frosty weather, if the mercury falls three or four divisions, there will be a thaw. But in a continued frost, if the mercury rises, it will certainly snow. When wet weather happens soon after the depression of the mercury, expect but little of it; on the contrary, expect but little fair weather, when it proves fair shortly after the mercury has risen. In wet weather, when the mercury rises much and high, and so continues for two or three days before the bad weather is entirely over, then a continuance of fair weather may be expected. In fair weather, when the mercury falls much and low, and thus continues for two or three days before the rain comes, then a deal of wet may be expected, and probably high winds. The words engraved on the scale are not so much to be attended to, as the rising and falling of the mercury; for if it stands at much rain, and then rises to changeable, it denotes fair weather, though not to continue so long as if the mercury had risen higher. If the mercury stands at fair, and falls to changeable, bad weather may be expected. In winter, spring, and autumn, the sudden falling of the mercury, and that for a large space, denotes high winds and storms; but in summer it presages heavy showers, and often thunder. It always sinks very low for great winds, though not accompanied with rain; but it falls more for wind and rain together, than for either of them alone. If, after rain, the wind change into any part of the north, with a clear and dry sky, and the mercury rise, it is a certain sign of fair weather. After very great storms of wind, when the mercury has been low, it commonly rises again very fast. In settled fair weather, except the mercury sink much, expect but little rain. In a wet season, the smallest depression must be attended to; for when the air is much inclined to showers, a little sinking in the barometer denotes more rain. And in such a season, if it rise suddenly fast and high, fair weather cannot be expected to last more than a day or two. The greatest heights of the mercury are found upon easterly and north-easterly winds; and it may often rain or snow, the wind being in these points, while the barometer is in a rising state, the effects of the wind counteracting its influence. But the mercury sinks for wind as well as rain in all other points of the compass. New Method of Preserving Birds.—(From the Annual Register.) When I receive a bird fresh taken, (says the author,) I open the venter, from the lower part of the breast-bone down to the anus, with a pair of scissars, and extract all the contents. This cavity I immediately fill up with the following mixture, and then bring the wound together by a suture, so as to prevent the stuffing from coming out. The gullet or passage I fill, from the beak down to where the stomach lies, with the mixture finer ground, which must be forced down a little at a time, by the help of a quill or wire: the head I open near the root of the tongue, with the scissars, and, after having turned out the brains, I fill the cavity with the same mixture. The mixture is: common salt, one pound; alum, powdered, four ounces; ground pepper, two ounces; all blended together. To take the Impression of the Wings of a Butterfly in all their Colours. Kill it without spoiling; cut off the body close to the wings, which contrive to spread in a flying position; then take a piece of white paper, wash part of it with thick gum-water; when dry, lay it on a smooth board, with the wings on the gum-water; lay another paper over this, press both very hard, let them remain under pressure for an hour; afterwards take off the wings of the butterfly, and you will find a perfect impression of them, with all their various colours, remaining on the paper. Draw, between the wings of the impression, the body of the butterfly, and colour it after life. To take the Impression of a Leaf of any Tree, Plant, or Shrub, with all its Veins. Having put the intended leaf into a book for a few minutes, which will cause it to lie very flat, you must have a pair of balls, somewhat of the shape of those used by printers; have them covered with kid-skin, that being the best leather for the purpose. These balls may be made to any size. You must then procure some lamp-black, ground or mixed with drying oil, and having put a small quantity on one of the balls, spread it all over with the other till they are both black; then laying the leaf on one of them, place the other over it, and press both very hard together. When the leaf is sufficiently black, take it off the ball, and place it between a sheet of white paper. Press it gently with your hand, the heat and pressure of which will cause it to receive an accurate delineation of all its veins. Curious Experiments respecting Colours. The following curious and useful remarks on the different degrees of heat imbibed from the sun’s rays, &c. by cloths of different colours, were extracted from “Experiments and Observations,” by that famous American philosopher and politician, Dr. B. Franklin. “First, let me mention an experiment you may easily make yourself. Walk but a quarter of an hour in your garden when the sun shines, with a part of your dress white, and a part black; then apply your hand to them alternately, and you will find a very great difference in their warmth. The black will be quite hot to the touch, the white still cool. “Another. Try to fire paper with a burning-glass. If it be white, you will not easily burn it; but if you bring the focus to a black spot, or upon letters written or printed, the paper will immediately be on fire under the letters. “Thus fullers and dyers find that black cloths, of equal thickness with white ones, and hung out equally wet, dry in the sun much sooner than the white, being more readily heated by the sun’s rays. It is the same before a fire; the heat of which sooner penetrates black stockings than white ones, and is apt sooner to burn a man’s shins. Also beer much sooner warms in a black mug set before the fire, than in a white one, or in a bright silver tankard. “My experiment was this: I took a number of little square pieces of broad cloth from a tailor’s pattern-card, of various colours. There were black, deep blue, lighter blue, green, purple, red, yellow, white, and other colours, or shades of colours. I laid them all out upon the snow in a bright sunshiny morning. In a few hours, (I cannot now be exact as to the time,) the black being warmed most by the sun, was sunk so low as to be below the stroke of the sun’s rays; the dark blue almost as low, the lighter blue not quite so low as the dark, the other colours less as they were lighter; and the quite white remained on the surface of the snow, not having entered it at all. “What signifies philosophy that does not apply to some use? May we not learn from hence, that black cloths are not so fit to wear in a hot sunny climate, or season, as white ones; because, in such clothes the body is more heated by the sun when we walk abroad, and are at the same time heated by the exercise, which double heat is apt to bring on putrid dangerous fevers?—that soldiers and seamen, who must march Thirty Soldiers having deserted, so to place them in a Ring, that you may save any Fifteen you please, and it shall seem the Effect of Chance. This recreation is usually proposed thus: Fifteen Christians and fifteen Turks being in a ship at sea, in a violent tempest, it was deemed necessary to throw half the number of persons overboard, in order to disburden the ship, and save the rest; to effect this, it was agreed to be done by lot, in such a manner, that the persons being placed in a ring, every ninth man should be cast into the sea, till one half of them were thrown overboard. Now, the pilot, being a Christian, was desirous of saving those of his own persuasion: how ought he therefore to dispose the crew, so that the lot might always fall upon the Turks? This question may be resolved by placing the men according to the numbers annexed to the vowels in the words of the following verse:—
from which it appears, that you must place four of those you would save first; then five of those you would punish. After this, two of those to be saved, and one to be punished; and so on. When this is done, you must enter the ring, and beginning with the first of the four men you intend to save, count on to nine; and turn this man out to be punished; then count on, in like manner, to the next ninth man, and turn him out to be punished; and so on for the rest. It is reported that Josephus, the author of the Jewish History, escaped the danger of death by means of this problem; Three Persons having each chosen, privately, one out of three Things,—to tell them which they have chosen. Let the three things, for instance, be a ring, a guinea, and a shilling, and let them be known privately to yourself by the vowels a, e, i, of which the first, a, signifies one, the second, e, two, and the third, i, three. Then take 24 counters, and give the first person 1, which signifies a, the second 2, which represents e, and the third 3, which stands for i; then, leaving the other counters upon the table, retire into another room, and bid him who has the ring take as many counters from the table as you gave him; he that has the guinea, twice as many, and he that has the shilling four times as many. This being done, consider to whom you gave one counter, to whom two, and to whom three; and as there were only twenty-four counters at first, there must necessarily remain either 1, 2, 3, 5, 6, or 7, on the table, or otherwise they must have failed in observing the directions you gave them. But if either of these numbers remain, as they ought, the question may be resolved by retaining in your memory the six following words:—
As, for instance, suppose the number that remained was 5; then the word belonging to it is semita; and as the vowels in the first two syllables of this word are e and i, it shews, according to the former directions, that he to whom you gave two counters has the ring; he to whom you gave three counters, the gold; and the other person, of course, the silver, it being the second vowel which represents 2, and the third which represents 3. How to part an Eight Gallon Bottle of Wine equally between two Persons, using only two other Bottles, one of Five Gallons, and the other of Three. This question is usually proposed in the following manner: In order to answer the question, let the eight-gallon bottle be called A, the five-gallon bottle B, and the three-gallon bottle C; then, if the liquor be poured out of one bottle into another, according to the manner denoted in either of the two following examples, the proposed conditions will be answered.
A Quantity of Eggs being broken, to find how many there were without remembering the Number. An old woman, carrying eggs to market in a basket, met an unruly fellow, who broke them. Being taken before a magistrate, he was ordered to pay for them, provided the woman could tell how many she had; but she could only remember, that in counting them into the basket by twos, by threes, by fours, by fives, and by sixes, there always remained one; but in counting them in by sevens, there were none remaining. Now, in this case, how was the number to be ascertained? This is the same thing as to find a number, which being divided by 2, 3, 4, 5, and 6, there shall remain 1, but being divided by 7, there shall remain nothing; and the least number, which will answer the conditions of the question, is found to be 301, which was therefore the number of eggs the old woman had in her basket. To find the least Number of Weights, that will weigh, from One Pound to Forty. This problem may be resolved by the means of the geometrical progression, 1, 3, 9, 27, 81, &c. the property of which is such, that the last sum is twice the number of all the rest, In like manner, to find a fourteen-pound weight, put into one of the scales the one, three, and nine-pound weights, and into the other that of twenty-seven pounds, and it will evidently outweigh the other three by fourteen pounds; and so on for any other weight. To break a Stick which rests upon two Wine Glasses, without injuring the Glasses. Take a stick, (see Plate,) AB. fig. 1, of about the size of a common broomstick, and lay its two ends, AB, which ought to be pointed, upon the edges of two glasses placed upon two tables of equal height, so that it may rest lightly on the edge of each glass. Then take a kitchen poker, or a large stick, and give the other a smart blow, near the middle point c, and the stick AB will be broken, without in the least injuring the glasses: and even if the glasses be filled with wine, not a drop of it will be spilt, if the operation be properly performed. But on the contrary, if the stick were struck on the underside, so as to drive it up into the air, the glasses would be infallibly broken. A Number of Metals being mixed together in one Mass, to find the Quantity of each of them. Vitruvius, in his Architecture, reports, that Hiero, king of Sicily, having employed an artist to make a crown of pure gold, which was designed to be dedicated to the gods, suspected that the goldsmith had stolen part of the gold, and substituted silver in its place: being desirous of discovering the cheat, he proposed the question to Archimedes, desiring to know if he could, by his art, discover whether any other metal were mixed with the gold. This celebrated mathematician being soon afterwards bathing himself, observed, that as he entered the bath, the water ascended, and flowed out of it; and as he came out of it, the water descended in like manner: from which he inferred, that if a mass of pure gold, The way in which he applied this circumstance to the solution of the question proposed was this: he procured two masses, the one of pure gold, and the other of pure silver, each equal in weight to the crown, and consequently of unequal magnitudes; then immersing the three bodies separately in a vessel of water, and collecting the quantity of water expelled by each, he was presently enabled to detect the fraud, it being obvious, that if the crown expelled more water than the mass of gold, it must be mixed with silver or some baser metal. Suppose, for instance, in order to apply it to the question, that each of the three masses weighed eighteen pounds; and that the mass of gold displaced one pound of water, that of silver a pound and a half, and the crown one pound and a quarter only: then, since the mass of silver displaced half a pound of water more than the same weight of gold, and the crown a quarter of a pound more than the gold, it appears, from the rule of proportion, that half a pound is to eighteen pounds, as a quarter is to nine pounds; which was, therefore, the quantity of silver mixed in the crown. Since the time of Archimedes, several other methods have been devised for solving this problem; but the most natural and easy is, that of weighing the crown both in air and water, and observing the difference. To make a mutual Exchange of the Liquor in two Bottles, without using any other Vessel. Take two bottles, which are as nearly equal as possible, both in neck and belly, and let one be filled with oil, and the other with water; then clap the one that is full of water dexterously upon the other, so that the two necks shall exactly fit each other; and as the water is heavier than the oil, it will naturally descend into the lower bottle, and make the oil ascend into its place. In order to invert the bottle of water without spilling the contents, place a bit of thin writing paper over the mouth of the bottle; and when you have placed the bottle in the proper position, draw out the paper quickly and steadily. How to make a Peg that will exactly fit Three different Holes. Let one of the holes be circular, the other square, and the third an oval; then it is evident, that any cylindrical body, To place Three Sticks, or Tobacco Pipes, upon a Table, in such a manner that they may appear to be unsupported by any thing but themselves. Take one of the sticks, or pipes, (see Plate,) AB, fig. 2, and place it in an oblique position, with one of its ends, B, resting on the table; then put one of the other sticks, as CD, across this in such a manner that one end of it, D, may be raised, and the other touch the table at C. Having done this, take the third stick E, and complete the triangle with it, making one of its ends E rest on the table, and running it under the second, CD, in such a manner that it may rest upon the first, AB; then will the three sticks, thus placed, mutually support each other; and even if a small weight be laid upon them, it will not make them fall, but strengthen, and keep them firmer in their position. How to prevent a heavy Body from falling, by adding another heavier Body to it on that side towards which it inclines. On the edge of a shelf, or table, or any other horizontal surface, lay a key, (see Plate,) CD, fig. 3, in such a manner, that, being left to itself, it would fall to the ground; then, in order to prevent this, take a crooked stick DFG, with a weight, H, at the end of it; and having inserted one end of the stick in the open part of the key, at D, let it be so placed, that the weight H may fall perpendicularly under the edge of the table, and the body by these means will be effectually prevented from falling. The same thing may be done by hanging a weight at the end of a tobacco-pipe, a stick, or any other body; the best means of accomplishing which will be easily known by a few trials. To make a false Balance, that shall appear perfectly just when empty, or when loaded with unequal Weights. Take a balance, (see Plate,) DCE, fig. 4, the scales and arms of which are of such unequal weights and lengths, that the scale A may be in proportion to the scale B, as the length For example; suppose the arm CD is equal to three ounces, and the arm CE to two, and that the scale B weighs three ounces, and the scale A two; then the balance, in this case, will be exactly true when empty; and if a weight of two pounds be put into the scale A, and one of three pounds into B, they will still continue in equilibrio. But the fallacy in this, and all other cases of the same kind, may be easily detected, in shifting the weights from one scale to the other. How to lift up a Bottle with a Straw, or any other slight Substance. Take a straw, (see Plate,) AB, fig. 5, which is not broken or bruised, and bend one end of it into a sharp angle ABC; then if this end of the straw be put into the bottle, so that the bent part of it may rest against either of its sides, you may take the other end in your hand, and lift up the bottle by it without breaking the straw; and this will be the more easily done, according as the angular part of the straw approaches nearer to that which comes out of the bottle. How to make a Cone, or Pyramid, move upon a Table without Springs, or any other artificial Means. Take a cone, or pyramid, of paper, or any other light substance, and put a beetle, or some such small insect, privately under it; then, as the animal will naturally endeavour to free itself from its captivity, it will move the cone towards the edge of the table, and as soon as it comes there, will immediately return for fear of falling; and by moving backwards and forwards in this manner, will occasion much diversion to those who are ignorant of the cause. To make a Pen, which holds One Hundred Sheep, hold double the Number, by only adding two Hurdles more. In the first pen, or that which holds one hundred sheep, the hurdles must be so disposed, that there shall be only one at the top and bottom, and the rest in equal numbers on each side; then it is obvious, that if one hurdle more be placed at each end, the space enclosed must necessarily be double the former, and consequently will hold twice the number of sheep. An ingenious Recreation, called the Two Communicative Busts. Take two heads of plaster of Paris, and place them on pedestals on the opposite sides of a room. Then take a tin tube, of an inch in diameter, and let it pass from the ear of one head through the pedestal, and under the floor, to the mouth of the other, observing, that the end of the tube which is next the ear of one head, should be considerably larger than that which comes to the mouth of the other. The whole being so disposed that there may be no suspicion of a communication, let any person speak with a low voice into the ear of one bust, and the sound will be distinctly heard by anyone who shall place his ear to the mouth of the other; and if there be two tubes, one going to the ear, and the other to the mouth of each head, two persons may converse together, by applying their mouth and ear reciprocally to the mouth and ear of the busts, without being heard by any other persons in the room. Another Recreation of the same kind, called the Oracular Head. Place a bust on a pedestal in the corner of a room, and let there be two tubes, one of which goes from the mouth, and the other from the ear of the bust, through the pedestal and floor, to an under apartment. Then if a person be placed in the under room, by applying his ear to one of the tubes as soon as a proper signal is given, he will hear any question that is asked, and can immediately return an answer; and if wires be contrived to go from the under jaw and eyes of the bust, they may be made to move at the same time, and by these means appear to deliver the answer. It was by a contrivance of this kind, that Don Antonio de Moreno so much astonished the celebrated Knight of the Woeful Countenance, and his facetious squire Sancho Panza, by resolving certain doubts proposed by the former concerning his adventures in the cave of Montesinos, and the disenchantment of my lady Dulcinea. How to make a Piece of Metal, or any other heavy Body, swim upon the Surface of Water, like a Cork. The specific gravity of water is inferior to that of metals, and consequently water, absolutely speaking, cannot support a ball of iron or lead; but if this ball be flattened, and beat out to a very thin plate, it will, if put softly upon still water, be prevented from sinking, and will swim upon its surface like any light substance. In like manner, if a fine steel needle, But if you would have a metallic body of large dimensions to swim upon water, you must reduce it into a thin concave plate, like a kettle; in which case, as the air it contains, together with the body itself, weighs less than the same bulk of water, it cannot possibly sink; as is evident from large copper boats, or pontoons, by which whole armies have frequently passed over rivers without danger. If this concave metallic vessel be placed upon the water with its mouth downwards, it will swim as before, and the contained air will keep the bottom of it from being wet; for that the water will not rise into any hollow vessel which is immersed into it, may be made evident thus:—Take a glass tumbler, and plunge it into water with its mouth downwards, and you will find, when you take it out, that the inside of the vessel is perfectly dry, so that if a live coal were put there, it would not be extinguished. A curious Experiment, to prove that Two and Two do not make Four. Take a glass vessel with a long narrow neck, which, being filled with water, will hold exactly a quart; then put into this vessel a pint of water, and a pint of acid of vitriol, and you will presently perceive, that the mixture will not fill the vessel, as it did when a quart of water only was put into it. The acid of vitriol must be put in gradually, by little and little at a time, mixing each portion with the water before you add more, by shaking the bottle, and leaving its mouth open, otherwise the bottle will burst. The mixture in this case also possesses a considerable degree of heat, though the two ingredients of themselves are perfectly cold; and this phenomenon is not to be accounted for, by supposing that the acid of vitriol is received into the pores of the water, for then a small portion of it might be absorbed by the water, without augmenting its bulk, which is known not to be the case; but the very form of the bodies in this experiment is changed, there being, as Dr. Hooke, who first noticed the fact, observes, an actual penetration of dimensions. Chemistry also furnishes a number of other instances, which shew that two bodies, when mixed together, possess less space than when they are separate. An ingenious Method of Secret Writing, by means of corresponding Spaces. Take two pieces of pasteboard, or stiff paper, out of which cut a number of oblong figures, at different distances from Example.
A curious Experiment, which depends on an Optical Illusion. On the bottom of the vessel, (see Plate,) AIBD, fig. 6, place three pieces of money, as a half-crown, a shilling, and a sixpence; the first at E, the second at F, and the third at G. Then let a person be placed with his eye at H, so that he can see no farther into the vessel than I; and tell him, that by pouring water into the vessel, you will make him see three different pieces of money, which he may observe are not poured in with the water. For this purpose, desire him to keep himself steady in the same position, and, pouring the water in gently, that the pieces of money may not be moved out of their places, when it comes up to K, the piece G will become visible to him; when it comes up to L, he will see the two pieces G and F; and when it rises to M, all the three pieces will become visible: the cause of which is owing to the refraction of the rays of light, in their passage through the water; for while the vessel is empty, the ray HI will proceed in a straight line; but in proportion as it is filled with water, the ray will be bent into the several directions NG, OF, PE, and by these means the pieces are rendered visible. A curious Experiment, of nearly the same kind as the last, called Optical Augmentation. Take a large drinking-glass, of a conical figure, and having put a shilling into it, fill the glass about half full with water; This phenomenon is occasioned by your seeing the piece through the conical surface of the water, at the side of the glass, and through the flat surface at the top of the water, at the same time; for the conical surface dilates the rays, and makes the piece appear larger, while the flat surface only refracts them, and occasions the piece to be seen higher up in the glass, but still of its natural size. Another curious Experiment, called Optical Subtraction. Against the wainscot of a room fix three small pieces of paper, as A, B, C, fig. 7, (see Plate,) about a foot and a half or two feet asunder, at the height of your eye; and placing yourself directly before them, about five times the distance from them that the papers are from each other, shut one of your eyes and look at them with the other, and you will then see only two of those papers, suppose A and B; but altering the position of your eye, you will now see the third, and one of the first, suppose A; and by altering its position a second time, you will see B and C, but in neither case all three of them together. The cause of this phenomenon is, that one of the three pencils of rays, which come from these objects, falls on the optic nerve at D, whereas, to produce distinct vision, it is necessary that the rays of light fall on some part of the retina E, F, G, H. From this experiment, the use of having two eyes may be easily perceived; for he that has only one can never see three objects placed in this position; or all the parts of one object, of the same extent, without altering the situation of his eye. An Optical Experiment, shewing how to produce an Artificial Rainbow. In any room which has a window facing the sun, suspend a glass globe, filled with water, by a string which runs over a pulley, so that the sun’s rays may fall directly upon it; then drawing the globe gradually up, when it comes to the height of about forty degrees above the horizon, you will see, by placing yourself in a proper situation, the glass tinged with a purple colour; and by drawing it gradually higher up, the These appearances serve to illustrate the phenomena of natural rainbows, of which there are generally two, the one being about eight degrees above the other, and the order of their colours inverted, as in this experiment; the red being the uppermost colour in the lower bow, and the violet in the other. An artificial Rainbow may also be produced as follows. Take some water in your mouth, and turn your back to the sun; then if it be blown forcibly out against some dark or shady place, you will see the drops formed by the beams of the sun into an apparent rainbow, which, however, soon vanishes. A curious Optical Illusion, produced by means of a Concave Mirror. Take a glass bottle, (see Plate,) ABC, fig. 8, and fill it with water to the point B; leave the upper part, BC, empty, and cork it in the common manner; place this bottle opposite a concave mirror, and beyond its focus, so that it may appear reversed; then if you place yourself still farther from the mirror, the bottle will appear to you in the situation a b c. And in this apparent bottle it is remarkable, that the water, which, according to the laws of catoptrics, and all other experiments of this kind, should appear at a b, appears, on the contrary, at b c, the part a b seeming to be entirely empty. And if the bottle be inverted, and placed before the mirror, as in the under part of the figure, its image will appear in its natural erect position, but the water, which is in reality at b c, will appear at a b. And if, while the bottle is inverted, it be uncorked, and the water suffered to run gently out, it will appear, that while the part BC is emptying, the part a b in the image is filling; and if, when the bottle is partly empty, some drops of water fall from the bottom A, towards BC, it seems in the image as if there were formed at the bottom of the part a b bubbles of air arising from a to b, which is the part that seems full. The circumstances most remarkable in this experiment, are, first, not only to see an object where it is not, but also where its image is not; and, secondly, that of two objects, which It is, however, to be noted, that if any coloured liquor be put into the bottle instead of water, no such illusion will take place. There is one phenomenon more of this kind, which ought not to be omitted; for though it be common enough, it is also extremely pleasing, and easy to be performed. If you place yourself before a concave mirror, at a proper distance, your figure will appear inverted; and if you stretch out your hand towards the mirror, you will perceive another hand, which seems to meet and join it, though imperceptible to the touch. And if, instead of your hand, you make use of a drawn sword, and present it in such a manner that its point may be directed towards the focus of the rays reflected by the mirror, another sword will appear, and seem to encounter that in your hand. But it is to be observed, that to make this experiment succeed well, you must have a mirror of at least a foot in diameter, that you may see yourself in part; and if you have a mirror large enough to see your whole person, the illusion will be still more striking. How to make a violent Tempest, by means of artificial Rain and Hail. Make a hollow cylinder of wood, very thin at the sides, about eight or ten inches long, and two or three feet in diameter. Divide its inside into five equal partitions, by means of boards of about six inches wide; and let there be a space between them and the wooden circle, of about one-sixth of an inch; observing, that the boards are to be placed obliquely to each other. This being done, put into the cylinder four or five pounds of leaden shot, of a size that will easily pass through the opening left for this purpose; then turn the cylinder on its axis, and the sound of the machine, when in motion, will represent that of rain, which will increase with the velocity of the motion; and if a larger sort of shot be used, it will produce the sound of hail. Magic Square. This, in arithmetic, is a square figure made up of numbers in arithmetical proportion, so disposed in parallel and equal
Magic squares seem to have been so called, from their being used in the construction of talismans. Take another instance:—
where every row and diagonal in the magic square, makes just the sum 65, being the same as the two diagonals of the natural square. It is probable that these magic squares were so called, both because of this property in them, viz. that the ranks in every direction make the same sum, which appeared extremely surprising, especially in the more ignorant ages, when mathematics passed for magic; and because also of the superstitious operations they were employed in, as, the construction of talismans, &c.; for, according to the childish philosophy of those days, which ascribed virtues to numbers, what might not be expected from numbers so seemingly wonderful? The magic square was held in great veneration among the Egyptians, and the Pythagoreans their disciples, who, to add more efficacy and virtue to this square, dedicated it to the then known seven planets, divers ways, and engraved it upon a plate of the metal that was esteemed in sympathy with the planet. The square, thus dedicated, was enclosed by a regular polygon, inscribed into a circle, which was divided into as many equal parts as there were units in the side of the square; with the names of the angels of the planet, and the signs of the zodiac written upon the void spaces between the polygon and the circumference of the circumscribed circle. Such a talisman, | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
