The Thaumatrope.--A great improvement effected in its construction.--Another toy upon the same optical principle.

Tom’s holidays were now drawing to a close, and the children were summoned into the library to receive their last lesson in philosophy.

“You have lately witnessed an experiment,” said Mr. Seymour, “which must have convinced you how liable the ear is to be deluded with respect to the nature and direction of sound; I shall now show you that the eye has also its sources of fallacy.”

“If you proceed in this manner, you will make us all Cartesians,”^[63] exclaimed the vicar.

“I shall illustrate my subject by means of a new toy which I have lately invented,” said Mr. Seymour, “and unless I am much mistaken, it will afford as much amusement to the elder as to the younger members of our party, although the vicar may perhaps regard it as a more hostile instrument than even that of the wooden horse which filled unhappy Troy with an armed enemy. It is a small machine,” continued Mr. Seymour, “which is well calculated to furnish us with some capital puns.”

“With puns!” exclaimed the horrified vicar, who no sooner heard this appalling declaration, than like another Laocoon, he deprecated the introduction of the “donum exitiale” within the walls of Overton Lodge. But his hostility was soon disarmed, not by the circumvolutions of a snake around the body of the enraged orator, but by the embraces of little Rosa, who threw her arms around the neck of the vicar, with such supplicating grace, that at length he exclaimed, “Well, well; if it be the decree of the Fates, I must submit.”

During this altercation, Mr. Seymour had procured the “wooden engine” from his study.

“I will first,” said he, “exhibit the toy in its original state, and then show you the improvements which have been effected in it.”

“Let us hear the account of its operation,” said the major, “which I perceive is enclosed within the box.”

“True,” replied Mr. Seymour; “and I think you will agree that I have given a very plausible explanation of its effects.”

“Plausible,” muttered the vicar, “plausible enough, no doubt; oh the Sinon!”

Mr. Seymour then proceeded. “This toy is termed the THAUMATROPE.”

“Of Grecian origin!” observed the vicar. “‘Timeo Danaos et dona ferentes,’ as Virgil has it.”

“What is the meaning of the term?” asked Louisa. The vicar explained to her that it was compounded of the Greek words, ?a??a, and t?ep?; the former of which signified wonder, the latter to turn.

“Exactly,” replied Mr. Seymour. “‘A Wonder-turner,’ or a toy which performs wonders by turning round: but let me proceed in the explanation.” He then continued to read as follows: “This philosophical toy is founded upon the well-known optical principle, that an impression made on the retina of the eye lasts for a short interval after the object which produced it has been withdrawn. During the rapid whirling of the card, the figures on each of its sides are presented with such quick transition, that they both appear at the same instant, and thus occasion a very striking and magical effect. On each of these cards a device is introduced, with an appropriate motto, or epigram; the point of which is answered, or explained, by the change which the figure assumes during the rapid whirling of the card.”

“It may be very clever,” said the vicar, “but I do not understand it.”

“But you shortly will; look at one of the cards.”

Mr. Seymour then displayed a pasteboard circle, on the one side of which was figured a rat, and on the other, a cage; two strings were fastened in its axis, by which the card could easily be made to revolve, by means of the thumb and finger. Fearing that some of our readers may be as dull of comprehension as the vicar, we have introduced a sketch of the apparatus, in which both sides of the card are exhibited, with the strings by which it is whirled round.

No sooner had Mr. Seymour put the card in motion, than the vicar, in a tone of the greatest surprise, exclaimed, “Magic! magic! I declare the rat is in the cage!!”

“And what is the motto?” asked Louisa.

“Why is this rat like an opposition member in the House of Commons, who joins the ministry?” replied Mr. Seymour.

“Ha, ha, ha!--excellent!” cried the major, as he read the following answer: “because by turning round he gains a snug berth, but ceases to be free.”

“The very reverse to what occurred in ancient Rome, where the slave became free by turning round,” observed the vicar.

The vicar, no doubt, alluded to the custom of making a freeman, as described by Persius; from which it appears, that the clapping a cap on the head, and giving him a turn on the heel, were necessary circumstances. A slave thus qualified became a citizen of Rome, and was honoured with a name more than belonged to any of his forefathers, which Persius has repeated with a great deal of humour in his 5th satire:--

“Show us another card,” said Tom, eagerly.

“Here then is a watch-box; when I turn it round, you will see the watchman comfortably sleeping at his post.”

“Very good! It is very surprising,” said the vicar.

“Yes,” observed the major; “and to carry on your political joke, it may be said that, like most worthies who gain a post, by turning round, he sleeps over his duty.”

“The epigram which accompanies it is not deficient in point,” said Mr. Seymour.

“What have you there?” exclaimed the vicar; “arms and legs, without a body?”

“Yes,” replied Mr. Seymour; “and which, on turning round, will present the figure of a king, invested with all the insignia of royalty.”

“It is indeed a king. Look at his crown and sceptre!” cried Louisa.

“Now for the epigram,” said the major, who then read the following lines:--

The next card presented a laughing face, which on being turned round, was instantly changed into a weeping one. The motto--The sweetest things turn sour.

“The device is capital!” exclaimed the vicar, “I question whether Peter of Cortona ever produced a more striking metamorphosis.”^[64]

The other cards were now exhibited in succession, of which the box contained eighteen, and the whole party, not even excepting the vicar, were highly gratified with the amusement.

“But I have not yet read to you the author’s address to the public; and which, I must say, contains a succession of very happy puns.”

“Spare me! spare me!” cried the vicar: “I like your toy, but cannot discover the advantage of alloying amusement with such spurious wit, and of associating science with buffoonery.”

Mr. Seymour, however, was relentless, and thus proceeded: “It is well known that the Laputan philosopher invented a piece of machinery, by which works could be composed by a mechanical operation; and the Quarterly Review has asserted, that a certain English poem was fabricated in Paris, by the powers of a steam-engine; but the author of the present invention claims for himself the exclusive merit of having first constructed a hand-mill, by which puns and epigrams may be turned with as much ease as tunes are played on the hand-organ, and old jokes so rounded and changed, as to assume all the airs of originality. The inventor confidently anticipates the favour and patronage of an enlightened and liberal public, on the well-grounded assurance, that ‘one good turn deserves another;’ and he trusts that his discovery may afford the happy means of giving activity to wit that has been long stationary; of revolutionising the present system of standing jokes, and of putting into rapid circulation the most approved bon-mots.”

“Why, vicar, what ails thee?” exclaimed the major.

“Our subject has given him a turn; let him alone, and he will soon come round,” observed Mr. Seymour.

The whole party, with the exception of Mr. Twaddleton, laughed heartily; the vicar, however, did not relax a feature of his countenance.

As soon as this ebullition had subsided, the major enquired of Mr. Seymour, what was the nature of the improvement to which he had alluded.

“My proposed improvements refer both to the subjects exhibited on the cards, and to the mechanism by which their changes are effected,” replied Mr. Seymour.

“In the first place, it has occurred to me that this amusing toy might be made instrumental in impressing classical subjects upon the memory of young persons.”

This observation delighted the vicar, who said that he would patronise such an attempt with all his heart.

“Why can we not,” continued he, “thus represent the Metamorphoses of Ovid; or what say you, vicar, to converting the fleet of Æneas into sea-nymphs, as Virgil has it?”

“An elegant thought! upon my word; a most elegant conception!” exclaimed Mr. Twaddleton.

“What have we here?” interrupted the major, who had, for the first time, noticed the superscription on the cover of the box: “had I seen this before, I should have augured favourably of the toy: it is like the sign of an inn, which is held out to announce good entertainment within.” He then read the following:--

Mr. Seymour now proceeded to explain more fully the optical theory of the instrument, which neither Louisa nor Tom could, as yet, thoroughly understand.

He told them that an object was seen by the eye, in consequence of its image being delineated on the retina, or optic nerve, which is situated on the back part of the eye; and that it had been ascertained, by experiment, that the impression which the mind thus receives, lasts for about the eighth part of a second after the image is removed. “It is, therefore, sufficiently evident,” said Mr. Seymour, “that if any point, as a lighted stick, be made to revolve, so as to complete the circle in that period, we shall not see a fiery point, but a fiery circle; because the impression made by it in every point of its circuit will remain until it comes round again to the spot from which it set out;--but we will, at once, exemplify this fact by an experiment.”

Tom was accordingly directed to procure a piece of stick and a candle; and as soon as they were brought into the room, Mr. Seymour ignited the end of the stick and whirled it round, when a bright circle, without any intervals of darkness, was seen by the whole party.

“Never until this instant,” exclaimed the vicar, with an expression of high satisfaction, “did I fully appreciate the beauty of that passage in Milton, wherein the poet evidently describes the rapidity of Satan’s flight, as well as the refulgence of his appearance--

“Now to take in the full meaning of this figure,” continued Mr. Twaddleton, “we must imagine ourselves in chaos, and that a vast luminous body is rising near the spot where we may be supposed to be standing, so swiftly as to appear a continued track of light, and lessening to the view, according to the increase of distance, until it ends in a point, and then disappears; and all this must be supposed to strike our eye at one instant.”

“It is very probable,” said Mr. Seymour, “that the poet had such an idea in view, and that he intended by it to convey the immense rapidity of Satan’s flight. Homer makes use of the same figure to express the velocity of the javelin, d?????s???? e????, the ‘long shadowed’ javelin. We shall have ample proof of the effect of this power in the eye of retaining impressions, and of thus converting points into lines and circles, during the exhibition of your fire-works; and which, in fact, derive the greater part of their magical effect from it.”

“The pin wheel is certainly nothing more than a fiery circle produced by the rapid revolution of a jet of flame,” said the vicar.

“And the rocket,” added Mr. Seymour, “is a column of light occasioned by the same rapid movement of a burning body in a rectilinear or curved direction.”

“I perfectly understand all that you have said,” observed Tom.

“Then you will not have any difficulty in explaining the action of the Thaumatrope, for it depends upon the same optical principle; the impression made on the retina by the image, which is delineated on one side of the card, is not erased before that which is painted on the opposite side is presented to the eye; and the consequence is, that you see both sides at once.”

“Or, you might put it in this way,” said the major: “that as the image remains the eighth of a second on the retina, after it has been withdrawn from the eye, a revolution of eight times in a second will secure its uninterrupted continuance.”

“On turning round the card,” observed Louisa, “I perceive that every part of the figure is not equally distinct.”

“Because every part of the card does not revolve with the same velocity,” said her father; “and this fact offers a good illustration of what I formerly stated,^[65] that in circular motion, the parts more remote from the axis of rotation are those which move with the greater velocity. This toy will also be found capable of exemplifying another truth to which I have before alluded, that ‘the axis of motion remains at rest while all the parts revolve round it.’”^[66]

“I remember that very well,” exclaimed Tom.

“Then take the card, and spin it between yourself and the window, and tell me what you observe,” said his father.

“I see a dark line across the window; and what is very strange, the other parts of the card appear transparent; for they do not obstruct the view of the window, as they would if the card were at rest.”

“The dark line you see is the axis of rotation, which being stationary, necessarily excludes the light; the other parts being in motion do not remain a sufficient time to obliterate the image made on the eye by the window. It is true that the card disc passes between your eye and the light, but as it does not continue at any one point for more than the eighth of a second, there is no more apparent intermission of the light than what occurs during the winking of the eyes.”

“You allude to a very curious fact,” observed the vicar, “that, although we are perpetually covering the eyeballs with our eyelids, we are not conscious of the intervals of darkness.”

“The reason of which must surely be obvious from the explanation I have just offered,” said Mr. Seymour: “the sensation of light is not exchanged for that of darkness in so short a period as the twinkling of the eye.”

“I admit the plausibility of your theory,” said the vicar; “but it appears to me that objects frequently linger on the sight for a longer period than that which you assign to them. I well remember seeing the flame of a candle for several seconds after it had been suddenly withdrawn from the apartment.”

“I admit that strong lights frequently continue for some time thus visible in the ‘mind’s eye;’ and it is well known that such impressions are often followed by images of similar shape, but of various colours. In passing from sunshine to a dark room, we frequently witness the appearance of stars and circles of vari-coloured light; but this phenomenon is very distinct from that of the Thaumatrope, and is to be explained upon very different principles.”^[67]

“I know exactly to what you allude,” said the major: “and I do not doubt but that many of those illusive appearances, which have been described, might be referred to the operation of the same natural cause. It is easy to imagine that a person who has steadfastly fixed his eyes upon an illuminated object, may, for some minutes afterwards, see the same figure in shade; it was from such a cause, no doubt, that Constantine saw the image of a cross in the sky. You are, probably, acquainted with the opinions of Eusebius, Fabricius, and Dr. Lardner, upon this alleged miracle.”

“Yes,” exclaimed the vicar, “and I also know, that this miracle for the conversion of Constantine gave origin to the Catholic custom of illuminating the cross at St. Peter’s in Rome.”

“Sir David Brewster, in his late work on Natural Magic, has given us a beautiful illustration of the same principle; it is as follows,” said Mr. Seymour. “A figure dressed in black and mounted upon a white horse, was riding along exposed to the bright rays of the sun, which through a small opening in the clouds was throwing its light only upon that part of the landscape. The black figure was projected against a white cloud, and the white horse shone with particular brilliancy by its contrast with the dark soil against which it was seen. A person interested in the arrival of such a stranger, had been for some time following his movements with intense anxiety; but upon his disappearance behind a wood, was surprised to observe the spectre of the mounted stranger in the form of a white rider upon a black steed, and this spectre was seen for some time in the sky, or upon any pale ground to which the eye was directed.”

“I cannot understand why the spectre should be opposite in colour to the real image,” observed Tom.

“It is a law of vision which you must for the present take for granted,” answered his father; “that such is the fact, however,” continued he, “I will satisfy you by a very simple experiment.”

Mr. Seymour here placed three different coloured wafers in a triangular form on a piece of white paper, and instructed his son to fix his eyes steadily upon them for a minute; this having been performed, he next directed him to turn them from the wafers to a blank part of the paper, and to tell him what he saw.

“I see,” exclaimed Tom, “three spectral wafers, but the colours are different; the red wafer is represented by a green, the violet by a yellow, and the orange by a blue.”

“You now then understand what is meant by the spectral or accidental colour of a body:--But let us return to the subject of the Thaumatrope,” said Mr. Seymour.

“Behold!” continued he, “the Trojan ships!”

“Ay, ay, sure enough,” said the vicar; “but let me see, are their forms according to ancient authority? Very well indeed, Mr. Seymour. Very well; the poops have the bend so accurately described by Ovid and Virgil--‘puppesque recurvÆ,’ as the poet has it. And there is the triton; but is its size in proportion to the vessel? Yes, sir, you are doubtless correct, the figure is generally represented of considerable magnitude on ancient medals; and Silius Italicus, if my memory serves me, alludes to the weight of the image having on some occasions contributed to the wreck of the vessel.”

“Spin them round,” said Mr. Seymour.

The vicar complied; exclaiming at the same moment, “‘Vos ite solutÆ. Ite deÆ pelagi.’ They are positively converted into sea-nymphs. ‘Mirabile monstrum!’” cried Mr. Twaddleton.

“Here is another classical device; the representation of Eurydice, as she fell lifeless at the moment Orpheus turned round to gaze on her,” said Mr. Seymour.

“Charming! charming! I perceive that it is a copy from the splendid print of Didot in the Paris edition of Virgil.”

“Turn it round, vicar.”

“See! see! she revives, she opens her eyes, and throws her arms around the neck of her frantic lover: truly, Mr. Seymour, this is a most interesting toy,” said Mr. Twaddleton.

Mr. Seymour here observed that he had written an epigram to accompany the subject they had just witnessed, and he trusted that he had given to it a classical turn.

“By all means read it; the subject admits of much classical decoration,” observed the vicar.

Louisa received the epigram from the hands of her father, and read as follows:--

It could not be expected that Mr. Twaddleton should have admired lines so burdened with puns; but he quietly observed, “I should have preferred a quotation from the fourth Georgic, so beautifully descriptive of the fable.”

The next card that was presented for inspection exhibited the metamorphosis of Daphne into a laurel. As the figure revolved, the leaves were seen sprouting from her fingers, and her arms lengthening into branches.

“Come now,” said Mr. Seymour, “let us exhibit the figure which has been designed at my request: the change which it will undergo during its revolution may, I trust, on some day be realised; I only regret that it is not in my power to give the vicar so good a turn.”

“Really, if like Crambe, in Martinus Scriblerus, thou hadst a word for every day in the year, I should certainly say that you were this day under the dominion of the word turn.”

“You know this resemblance?” said Mr. Seymour, as he showed the figure, painted on one side of the card, to his daughter.

“It is the vicar!” exclaimed Louisa.

It was, indeed, a portrait of that most excellent character, represented in the costume in which he usually appeared.

“Turn it round,” said Mrs. Seymour.

Louisa twirled the cord, and the effect of the rotation was to convert the humble vicar into the dignified bishop; his meagre form was instantly changed into a corpulent figure, which was still farther inflated by the addition of the episcopal robe and lawn sleeves, while his angular features were softened by the graceful curves of an immense wig.

“I will give you a motto for it,” said the major, “and may it be prophetic!--RAPID PREFERMENT.”

“I will now show you the improvement which has been effected in the construction and use of this toy,” said Mr. Seymour. “It consists in altering the axis of rotation while the card is in the act of revolving, in order that the images on its opposite sides may be brought in different positions with respect to each other.”

“There cannot be any doubt that such would be the effect, were it possible to change the axis in the way you propose, but how is this to be effected?” asked the vicar.

“At first I attempted to produce the change by the addition of several other strings, but I soon found, that, in order to avail myself of this expedient, I should be obliged to stop the card before I could alter the axis, whereas my great object, as I have just stated, was to produce the change while the card was in the act of spinning,” answered Mr. Seymour.

“And I shrewdly suspect that such must necessarily be the case, adopt whatever expedient you may,” observed the major.

“No indeed; I have at length succeeded to my entire satisfaction, and that too by a most simple scheme, after having tried without success many very complicated contrivances.”

The party were very desirous of witnessing this triumph of skill, and Mr. Seymour produced the card, with its appendages, of which we shall here present our readers with an engraving:--

In all respects the card is constructed like the common Thaumatrope; the subject, it will be perceived, is that of a man drinking, the bottle being placed on one side, and the head on the other; upon revolving the card, in the ordinary manner, the two images will appear together as represented in:

The improvement consists in inserting in one, or, if a still greater change be desired, in both sides of the card, two strings, as seen in Fig. 1; viz. AD and AE, which united at A, form a common string for twirling the card. The cord AD is elastic, while the string AE is incapable of being stretched. If, therefore, while the card is in the act of spinning, the cord AD be pulled with an increased force, it will take the position DC, while the inelastic string AE will at the same time assume that of EC. The consequence of which will be that, instead of the card spinning on an axis in the direction AB, it will now spin on that which is in the direction CB, and we shall accordingly see the images on the opposite sides of the card in different positions, with respect to each other; at one moment the bottle will be seen in the hand of the drinker as represented in Fig.2, and in the next, at his mouth as shown in the cut below:

while, by alternately tightening and relaxing the string, the figure will be seen in the very act of raising and lowering the bottle.

Mr. Seymour having explained the principle of his improvement as we have above related, proceeded to exemplify it by a series of different subjects. We shall select two or three of them for the sake of illustration. A card with a jockey on one side and a horse on the other, on spinning round presented the combined figure; upon tightening the string, in the manner we have described, the card changed its axis, without the slightest halt or hesitation in its rotation, and the rider was in an instant canted over the head of his charger; in a moment, however, he appeared remounted; after which, by pulling the string, with different degrees of force, he was made to stand on the saddle, and to exhibit a number of different movements.

The figure of an Indian juggler was represented in the act of throwing up two balls; on spinning the card, and, at the same time, altering the position of the circle, in the manner already described, three, and afterwards four, became visible. When the card revolved upon its original axis, two of the balls on the reverse side coincided with the two painted on the front, so that during the revolution they fell upon the same spot on the retina, and therefore produced a single impression; but as soon as the position of the card was changed, these spots were brought upon different points, and consequently produced separate and independent images. By alternately tightening and relaxing the strings, the balls were seen in motion, arising from and falling into the hand of the juggler.

The next subject which we shall describe produced a considerable degree of merriment. The vicar inspected the drawing, and observed that he saw a pulpit placed on the banks of a pond; the card was made to spin, when a tailor was seen haranguing from the former, and a goose, at the same instant, fluttering over the water. The circle was now suddenly shifted, and the vicar was desired to state what he saw:--“Why, bless me!” exclaimed Mr. Twaddleton, “the tailor is justly served, he is ducked in the pond, while the goose has taken his place in the pulpit.”

Fearing that we may have exhausted the patience of our reader, we shall only relate one more example. It was a Turk, who, by means of the expedient we are illustrating, was made to draw his sabre, and cut off the head of his antagonist, which immediately fell into the hands of the decapitated person, who, like St. Denys, appeared as if walking off with perfect indifference.

“You must admit that these effects are no less novel than they are extraordinary, and that they are capable of almost endless variation,” said Mr. Seymour.

“I admit it all,” replied Mr. Twaddleton, “and I have only to express a hope that, amidst all your improvements, you will never lose sight of your first and most laudable design, that of rendering your toy subservient to classical illustration: your triumph will then be complete, and I shall willingly acknowledge that there is not only philosophy but literature in your sport.”

“I must not quit this subject,” said Mr. Seymour, “until I have exhibited another toy, which, like the Thaumatrope, is indebted for its effect to the optical principle, which I trust is now well understood by all present, viz. that an impression made on the retina lasts for a certain period after the object itself has been withdrawn.”

The annexed wood-cut represents the instrument to which Mr. Seymour alluded.

It consists of a disc of blackened tin plate, which is made to revolve on its axis in the manner above exhibited. A narrow opening extends from the circumference to the centre as seen at A. If a device of any kind, as a star (which for increasing the beauty of the experiment ought to be transparent, and illuminated with a lamp) be placed behind the disc, it is evident that, as long as the circle remains at rest, no other part of the figure can be visible than that which is immediately behind the slit A, but the instant it is put into rapid motion, the whole of the star will be seen, as exhibited in figure B.

Mr. Seymour observed that the explanation of the phenomenon was obvious;--each successive portion of the figure seen through the opening remains on the eye, until the circle has completed its entire revolution.

“This experiment,” continued Mr. Seymour, “admits of a very curious modification, which I shall now proceed to exhibit.”

Three coloured wafers were then placed, at equal distances from each other, on the disc, and the instrument having been arranged before a looking-glass, the party were desired to observe the reflected image as the circle revolved.

“The wafers are blended into one continuous zone,” observed Mrs. Seymour.

“To be sure,” said Louisa; “upon the same principle that the ignited stick appears as a fiery circle.”

“It would be very strange, after the different experiments we have seen, if we were not able to explain the present appearance,” observed Tom.

“The fiery circle produced by the revolving stick is a much better illustration of the principle; I do not see what object Mr. Seymour has in thus multiplying his experiments,” said the vicar.

“Gently, if you please, Mr. Twaddleton, and, before you favour us with your criticism, wait until I have concluded my experiment. You have seen that the reflected image of the revolving wafers appears as a continuous zone, and you have very correctly explained the reason of such an appearance; but I must now request you to inspect the reflected image through the slit in the disc, as it revolves, and say what new effect you observe.”

“How very strange!” exclaimed Tom; “I see the three wafers very distinctly, and perfectly at rest.”

“Impossible,” exclaimed the vicar--“let me have a peep. Why, I declare, they appear, as you say, stationary, although I know them to be in rapid motion; as sure as fate I shall become a Cartesian.”

The Major, Louisa, and Mrs. Seymour, were all equally surprised, and incapable of giving any explanation of the phenomenon they had witnessed.

“Let us remember,” said Mr. Seymour, “that in viewing the image through the slit in the revolving disc, we catch but a momentary glance as it passes before the eye, and that the image thus produced on the retina is retained until the next revolution again brings the slit into the same position. Now it is evident, that before the eye can ascertain a body to be in motion, it must observe it in two successive portions of time, in order to compare its change of place;^[68] but in the experiment under consideration, the glance is momentary, the wafer is no sooner seen than it passes away; its figure alone is impressed upon the retina, and this impression is continued without any change, until the circle completes its round, and consequently the image must appear at rest.”

“I understand you; the figure, but not the motion, of the wafer, is discernible in the short period during which it is visible through the slit,” observed the vicar.

“I lately witnessed a beautiful illustration of this subject at the Royal Institution,” said Mr. Seymour. “A number of cogged wheels, cut out of pasteboard, were set in motion in a perfectly dark room, when occasional flashes of light from an electric battery, displayed their forms most distinctly, and yet although whirling round at the time, they appeared to the spectator as motionless as so many solid blocks of marble. In like manner, in a storm during the darkness of midnight, the rolling ship and waves, when rendered visible by flashes of lightning, will appear as completely at rest, as a representation of them upon the canvass.[68a] I may at some future time extend this interesting subject, by exhibiting some optical illusions produced by the revolution of wheels in different directions, and at different velocities, for the knowledge^[69] of which we are indebted to Mr. Faraday, and in mentioning that distinguished philosopher,” added Mr. Seymour, addressing himself more particularly to the vicar, “I cannot avoid remarking, that if Philosophy in Sport can be made Science in Earnest, the juvenile lectures delivered by that professor have established the converse proposition, that the sternness of Science may be relaxed into the engaging aspect of Sport.”

“Before quitting this subject,” continued he, “I have yet another toy in store for your amusement; it is founded upon the optical principle which I have every reason to believe you now thoroughly understand.” A square box was then produced containing a number of card discs, the edges of which exhibited a series of notches corresponding with the figures delineated on their margins. That the reader may better understand their construction, as well as the explanation of Mr. Seymour, the following representation has been introduced.

“To exhibit the magical effects of this toy,” said Mr. Seymour, “I will, by means of the spindle to which it is attached, cause it to revolve rapidly before the looking-glass, and you shall view the reflection through the openings.”

Each member of the party obeyed in succession the direction thus given, and severally expressed the great astonishment they felt, at observing the figures in constant motion, and exhibiting the most grotesque attitudes.

“Now,” said Mr. Seymour, “attend to my explanation. Each figure is seen through the aperture, and as it passes and is succeeded in rapid succession by another and another, differing from the former only in attitude, the eye is cheated into the belief of its being the same object successively changing the position of its body. Consider what takes place in an image on the retina when we actually witness a man in motion; for instance, a man jumping over a gate, in the first moment he appears on the ground, in the next his legs are a few inches above it, in the third they are nearly on a level with the rail, in the fourth he is above it, and then in the successive moments he is seen descending as he had previously risen. A precisely similar effect is produced on the retina, by the successive substitution of figures in corresponding attitudes, as seen through the orifices of the revolving disc; each figure remaining on the retina long enough to allow its successor to take its place without an interval that would destroy the illusion.”

“Nothing can be more satisfactory than your explanation of this very extraordinary toy,” observed the vicar.

“I am now about to exhibit what I consider a great improvement in its construction, inasmuch as we thus get rid of the mirror, and enable two persons to witness the deception at the same time,” said Mr. Seymour. “For this purpose I have a spindle, at each end of which a disc is placed, and which I hold in my hand.” We deem it expedient to illustrate this arrangement by a wood-cut.

“By revolving the spindle, you perceive that both cards are made to turn round with equal velocity. Tom,” said his father, “look through the orifices of the disc, on my right hand, and Louisa, do the same on my left.” The children obeyed, and simultaneously expressed their wonder at what they witnessed. “The figures are all dancing!” cried Tom; “The horses are all prancing!” exclaimed Louisa.

“You have not yet told us the name of this toy,” observed the vicar.

“It has received several names,” answered Mr. Seymour, “as Phantasmascope, Phenakistiscope, &c. derived, as you no doubt perceive, from the Greek.”

It is scarcely necessary to observe, that the appearances thus produced may be infinitely varied--heads opening their mouths, and distorting their countenances; creeping serpents, and machinery in active operation, are amongst the subjects that have excited the greatest admiration.

The party now dispersed, not less gratified than they had been instructed by the lesson of the morning.

The mighty magician of the North has compared the course of a narrative to the progress of a stone rolled down hill by an idle truant boy, “which at first moveth slowly, avoiding by inflection every obstacle of the least importance; but when it has attained its full impulse, and draws near the conclusion of its career, it smokes and thunders down, making a rood at every spring, clearing hedge and ditch like a Yorkshire huntsman, and becoming most furiously rapid in its course when it is nearest to being consigned to rest for ever: even such,” says he, “is the course of a narrative; the earlier events are studiously dwelt upon; but when the story draws near its close, we hurry over the circumstances, however important, which your imagination must have forestalled, and leave you to suppose those things which it would be abusing your patience to relate at length.”

Let the reader of the present work accept this explanation, as an apology for the abrupt and rapid manner in which we shall now accelerate our narrative. Since the last lecture, our history has advanced nearly three weeks, during which interval the major had made every arrangement for the approaching marriage. It was finally agreed that the ceremony should be performed at Overton church; and as the “happy couple” expressed a wish to pass their “honey moon” in a retired part of Yorkshire, the major consented to postpone his fÊte until after their return; nor was he displeased at such an arrangement, as it afforded time for getting up his entertainment on a more liberal scale than could otherwise have been accomplished. We shall now avail ourselves of that peculiar Lethean property which has been often ascribed to the pen of the author, and commit the reader to the arms of Morpheus, where it is our intention that he shall remain until the morning of the nuptials.

Reader, awake! the sun has risen, and Nature is robing herself in her most gorgeous apparel for the approaching ceremony; the family of the lodge have been already roused from their slumbers by the attendance of minstrels, whom the vicar had directed to salute the bridal party at break of day.----But hark! while we are thus trifling, the village of Overton is in a bustle; the marriage ceremony is over; the bells of the church are ringing right merrily their festive peals; many a handkerchief is waving from the cottage windows, while the doors are decorated with garlands; the vicarage is ornamented with fragments of Venetian tapestry; the peasants, dressed in their holiday garments, are carrying nosegays in their hands, to present to the bride as an offering of their respect, or to strew in her path, as an emblematic expression of their wishes.

The party having reached Osterley Park, we were proceeding to describe the banquet which had been prepared, and the various devices and emblems with which it had been decorated, under the classical direction of the vicar, when alas! our publishers, like the harpies of old, unexpectedly pounced upon us, and warned us from the feast--“diripiuntque dapes,” as Virgil has it.

“You have already exceeded the prescribed limits--you must close the scene--remember that you have engaged to condense the work into one volume,” said they. We remonstrate, but in vain. We request but a few pages, in order that we may give our characters a dramatic exit; but they reply to us in the words of Sneer, in the Critic, “O never mind! so as you get them off the stage, I’ll answer for it the reader won’t care how.”

You see then, gentle reader, how vain it would be to struggle against such arbitrary and tasteless masters; we shall, therefore, without any farther apology, ring the manager’s bell, and drop the curtain.

63.The Cartesians maintained that the senses were the great sources of deception; that everything with which they present us ought to be suspected as false, or at least dubious, until our reason has confirmed the report.