All branches of applied science are capable of giving us important hints and rendering us great service in all the conditions of our daily life, and as we have at various times throughout this volume mentioned useful domestic inventions applicable for use by means of water, air, etc., we may describe some more particularly relating to the inside of the house, and the science of domestic economy.

Sometimes during the winter we may feel it very difficult, if not impossible, to keep the room warm. This we can do, however, by means of double windows.

Why is it that the double window as used in Russia keeps out the cold so well? Is it because the room is defended against frost by two windows instead of there being only one to resist it?—Not entirely. Such an explanation is not sufficient. If one be protected against the exterior cold, it is, thanks to the mass of air which is imprisoned, between the two windows. Extraordinary as it may appear, the air is a very bad conductor of heat, and forms the best insulator that one can find. The heat of the apartment is then perfectly retained by means of the air between the double windows.

In the same way the double window is not less useful during the summer, for it prevents the entrance of the heated air into the house. The double window may therefore be compared to the bournous of the Arab and the cloak of the Spaniard, which preserves from heat as well as guards against cold.

The double windows also perform another service. The glasses form a hot-house. The sun heats the air which is enclosed, and thus between the panes ferns and even vines will flourish. The windows are very easy to make, and in the event of any reader desiring to construct one or more, we give the dimensions. (See fig. 885.)

T T, is the exterior frame of the window. The two panes are mounted on a frame of wood, and are represented by A A´ and B B´ The sashes are represented apart, P and P´ are the shutters of sheet iron, which, if the walls be not so thick as represented, can be replaced by a spring-blind, which descends between the windows.

Sewing Machine worked by a Dog.

Animals have been employed for all time to draw carriages and the plough, etc. But these animal “motors” are usually employed under defective conditions, and therefore without full profit. The inert mass of the animals remains quite unutilized, his force only is employed, and there are many objections on the score of humanity, as well as from a mechanical standpoint, and great muscular tension with suffering may be inflicted upon an animal which is continually mounting a wheel or such contrivance for raising water. There was in the Paris Exhibition a threshing machine put in motion by a horse walking upon a pair of rollers which constituted an “endless” way, and we will now briefly describe a machine which utilizes animal force and weight. It is the invention of M. Richard of Paris, who has made many mechanical apparatus for industrial purposes.

The principle of the invention (fig. 886) consists in the animal utilizing all the force resulting from his dead-weight. A small box contains the dog very easily. In the illustration we see the dog at rest, and in that case he maintains his centre of gravity and exercises no force upon the wheel. But when the box is inclined, the mere weight of the animal is sufficient merely to turn the wheel in the direction of the arrows. The dog, finding himself sliding away, naturally endeavours to move forward, and the rotation of the wheel is continued; the best results are obtained when the body is placed entirely upon the descending line, and this result is owing only to the weight of the animal.

There is a resting-place, just above and outside the “endless” way traversed by the dog. A basin with water is also provided for the animal.

M. Robert was let to this discovery in the following way:—He employs a large number of sewing-machine hands, and finding that the working of the machines had an injurious effect upon the health of the workers, he determined to substitute, in part, other labour for that of female hands. He then thought out his “quadrupedal motors,” which are worked by intelligent dogs. There is very little trouble or expense connected with the working, so a great saving is effected, as the dogs cost little, and are cheaply fed. The result is that M. Robert has four heavy machines occasionally at work, which are kept in motion by dogs at a very small expense.

A Clock-Lamp.

The illustration (fig. 887) represents an ingenious arrangement, which, by means of combustion of oil in a lamp, indicates the hour of the night. The design explains itself. Two vertical tubes are fixed above the reservoir of oil. The left tube contains oil, and is marked with the hours; the right tube burns the oil as a lamp.

The apparatus is so constructed by the inventor, M. H. Behn, that a certain quantity of oil is consumed exactly in one hour between two graduations of the hour-tube. A reflector placed beside the lamp enables one to see the time by night very plainly.

An “Alarum” Lamp.

The apparatus represented below (fig. 888) is an ordinary “alarum” lamp. It is surmounted by a petroleum lamp, which carries a burner that remains lighted all night, and which serves as a night-light. The “alarum” carries an index, represented by the dotted lines in the illustration, and the hands are fixed (with the index) to the hour you wish to rise in the morning. The index is fitted with an arrangement which lets loose a vertical bar represented on the right of the figure. This bar is held by a spring, and carries a toothed rack which acts upon and raises the wick. At the proper time the bar is loosed, and the lamp-wick is raised, diffusing a strong and sudden light through the apartment. This illumination, in concert with an alarum-bell, generally succeeds in awaking the heaviest sleeper.

A Good Petroleum Lamp.

This lamp (fig. 889) burns gazoline without the least odour or danger of explosion. It will serve equally well for petroleum or naphtha. The gazoline used ought to be 660 grammes weight to the litre.

The central portion of the lamp under consideration has an orifice, A B, which extends through the upper part, and by which the air is admitted to the centre of the flame. Two vertical plates divide the air-current into four portions. The chimney-rest, or gallery, forms with the glass three concentric envelopes, so arranged in stages that the air, when it reaches the plates, may be more and more carried under the flame. The orifices, a b, carefully regulated, give access to the exterior air. Including the central one, there are four currents of air, of which three strike against the flame. These are very excellent conditions for obtaining perfect combustion, and, consequently, there is an entire absence of smell and smoke, while the light is very powerful.

We may add that any glass will be found suitable to this lamp, and that, in consequence of the separation of the hot air by the currents mentioned, all danger of the glasses breaking from over-heating is avoided. In provincial districts, where lamp-glasses are not plentiful, this characteristic will be appreciated. The lamp can only be filled when it is extinguished, and thus the chances of explosion are practically obviated. A burner of twelve lines will give double the light of a moderator of the same capacity, and cost only a penny or less per hour. The light is perfectly still and clear.

A New Tap.

This new tap is the invention of M. Guyonnet, a Frenchman. The illustration (fig. 890) gives a very good idea of its construction, and it permits the gradual release of the liquid without any of the sudden rush which ordinary taps, or “bungs,” are apt to do. The plug is covered with indiarubber, and follows a double curve, which reduces the force of the liquid, and the indiarubber removes any incrustation from the bung hole into which it may be fitted, and closes the aperture effectively without force.

In order to guard against a contingency, which, however, is an unlikely one, the “envelope” (casing) has been made in two pieces, one of which can never be displaced; the head only can be moved, and it is easily detached. The plug adapts itself to the aperture as a button to the buttonhole, and only costs about three halfpence (15 centimes). Ice has no effect upon the aperture of the barrel, thanks to the indiarubber covering of the plug. So, altogether, such a tap will be found useful and very cheap.

The Trapeze and Swing.

We may here notice the simple trapeze and swing for children, which can be easily fitted up in any house between two rooms. The advantages of gymnastics for the young are incontestable, but practically there are difficulties in the way, particularly for those living in towns, but a skilful American has solved the problem in an ingenious way. He has found means to suspend the trapeze and a swing between the doorposts of a room without nails or any unsightly wood supports. The trapeze is simply suspended as represented in the accompanying illustrations.

The bar, B (see fig. 892), is of wood, terminating in screws enclosed in the grooves of the wood, at the extremity of which indiarubber discs are fixed (C and C´). When the bar is placed between the side posts of the open door and with the indiarubber in contact with the sides, the bar, B, is vigorously screwed in the direction of the arrow, and this motion is transmitted to the indiarubber discs which press against the door, and the apparatus remains fixed. The trapeze cords, or the swing ropes, can be fastened to the bar with hooks, as shown in the illustration, and the solidity and safety of the bar may be tested by putting heavy weights upon the ropes before venturing upon the swing, or trapeze. Even violent exercises may be indulged in without any fear of falling if the bar be firmly screwed against the sides of the door.

Simple Toys.

The accompanying illustration shows us a circlet of paper, very thin, fastened upon a frame, with paper wings fixed to the radii. This “screw” fashioned wings and the circlet can be kept up in the air by means of a hand screen. The effect will be observable in the rapid revolution of the little paper wheel, which must be very light and thin. (See fig. 893.)

There are many toys which can be controlled by the use of indiarubber springs. The bicyclist in the cut (fig. 894) is an instance in point. He turns around a pivot, and the tension of the spring keeps the machine in its place.

The swimming-fish (fig. 895) is moved by an indiarubber spring, much as the drawing-room kite is elevated in the air. The spring of indiarubber is twisted to make the fish swim, and the caoutchouc is adapted to a toothed wheel which has a clock-work motion that gives the tail a motion sideways and round, acting like a propeller, and thus the fish swims.

It is perhaps as well to say how these fish are managed, because then children will not break them, when they have been purchased, to see what is inside. Very young students are very fond of analyses of this nature, but synthesis, or putting together, is a far superior occupation in these circumstances to analysis, and to put together more lawful than to pull asunder.

Tree-felling by Steam.

The machine constructed a few years ago by Messrs. Ransome, and which was tried at Roupell Park, near London, seems to combine all the desiderata in the matter of mechanical tree-felling. Many experiments have been previously made by people to cut down trees by means of steam machinery, but none of them included all the conditions necessary for success. The Ransome Machine cut down four large trees in forty minutes.

The apparatus, as shown in the illustration, is not unlike, in appearance, the perforating machines employed in boring rocks, in which the drill is replaced by a saw. The cylinder is small, and works at high pressure; a piston moves the saw in a guide-frame. The machine is firmly fixed against the tree, and the support is fastened by a chain.

A rack arrangement provides for the turning of the machine as the saw continues to cut its way through the trunk of the tree.

The weight is not excessive, and the necessary steam is supplied by a portable furnace and boiler, which communicates with the saw-motion by a flexible tube. The saw can cut through a horizontal as well as through a perpendicular trunk—thus timber can be rapidly cut up.

Another ingenious sawing machine is that invented by Mr. W. W. Giles, of Chicago, United States, America. This apparatus is about eight feet long, and one extremity is fixed to the trunk of the tree to be operated on.

The operator sits upon a ledge or saddle at the opposite end, and putting his feet upon the treadles, pushes them and the saw forward; this movement is assisted by the weight of the hands on the lever. The saw, under these circumstances, cuts into the wood with great force, and when the operator pushes the lever forward he brings the force of his legs to bear at the same time, and carries the saw back again. So feet, hands, dead weight with the saw itself, combine at once upon the tree, and the blade quickly does its work. The saw is three feet long and is very easily manipulated.

A Way of Preserving Grapes.

Remarkable progress has been made of late years in the conservation of various articles of food, and we may here speak of the preservation of the grape.

We will first mention M. R. Charmoux’s method, which is called the “Fresh Grape” system. The portion of the building used for the business is on the first floor, as nearly as possible in the centre of the building, so as to be guarded from damp. Two windows are sufficient for all purposes, one to the north, and one to the south. They may be merely kept shut on ordinary occasions, but when frost comes they must be draped and “packed” with nets filled with moss or dried seaweed. The principal one of the windows is to admit of the cleansing of the room and for the admission of air in the summer time, when there are not many grapes left.

In winter the apartment may be warmed by hot air, and if this cannot be managed the ordinary means must be resorted to to keep up the temperature. The upper clusters of grapes should first be picked, for shade conduces to longevity of the fruit, and the 20th October is about the time to commence. A fine day should be chosen; a cloudy day will suit provided there is no dew or dampness in the air.

The finest bunches are cut first, and care must be taken to separate them at the end of the stalk, having three “eyes” under the grape and two above it. The leaves should be at once cut off, and the grapes put with great caution into boxes or baskets to be taken to the preserving house, where each stalk is plunged into a phial holding about 125 grammes of water, into which, two or three days previously, a teaspoonful of wood charcoal has been put.

The phials are suspended as shown in the accompanying illustration (fig. 899), and then certain precautions must be observed: they must not be disturbed, nor must any draught be admitted, as the temperature must not descend below 1° to 2° cent. There is no necessity to change the water in the bottles; very little will evaporate between November and May, when the process ought to be finished, but the phials must neither be corked nor concealed.

In the dry process the same house can be used, and stagings are employed. These frames are furnished with grooved boxes inclined towards each other, and lined with very dry fern-leaves or straw (fig. 900). Some days after the phials have been filled cut the grapes successively at the first time, which generally begins about the 6th to the 12th of November. The grapes are then put in baskets and carefully carried to the preserving room, where they are ranged in the boxes so as not to touch. Each box contains about six kilogrammes of grapes.

All the time of the conservation process care must be taken to eradicate all grapes which change colour or alter in any way. If dampness be feared have a lighted stove in the room for a time. Grapes are also preserved en espalier, but not so well. Sometimes a mouldy smell will be perceived in the room; to prevent this ventilators should be placed in the ceiling, which must, however, never be opened until the mouldy smell renders such a proceeding absolutely necessary.