Chapter I: Part 1

Transcriber’s Notes:

Text enclosed by underscores is in italics (_italics_), and text enclosed by equal signs is in bold (=bold=).

The whole number part of a mixed fraction is separated from the fractional part with -, for example, 2-1/2.

Additional Transcriber’s Notes are at the end.

How to Become an Inventor.

CONTAINING
Experiments in Photography, Hydraulics,
Galvanism and Electricity,
MAGNETISM, HEAT,
AND THE
Wonders of the Microscope.

ALSO GIVING
Instruction in the Use of Tools
AND
OPTICAL INSTRUMENTS.

NEW YORK:
FRANK TOUSEY, Publisher,
29 WEST 26TH STREET.

* * * * *

Entered according to Act of Congress, in the year 1898, by

FRANK TOUSEY,

in the Office of the Librarian of Congress at Washington, D.C.

How to Become an Inventor.

Nothing is more useful to a youth than to be able to do a little carpentering. To be handy with a chisel and saw, a nail and a hammer, saves many a dollar in the course of the year. If you call in a carpenter for a little work he is sure to spin out a “regular job.” I remember once buying some oak saplings, which cost me fifteen cents a stick; and wanting to build a summer-house, I required eight of them to be sawn through, so I applied to a carpenter, and the sticks were cut, but, to my astonishment, four dollars was charged for this little “job,” although the wood cost me only one dollar and thirty cents. I found out afterwards that the proper price for sawing would have amounted to about one dollar, so that three dollars profit was clapped on for the benefit of my experience. I just mention this to show my young friends that if they wish to make summer-houses for their gardens, cages for their birds, fowl-houses, rabbit-hutches, or boxes for their books, they must learn to make them for themselves. I shall therefore offer them a little advice upon “carpentering.”

THE SHOP AND BENCH.

Endeavor to procure some small outhouse, in which you may erect what is called a carpenter’s or joiner’s bench. These may very often be bought second-hand, or if not, can easily be procured at a reasonable rate. I am very particular in recommending a bench, as without it you will find many obstacles to your work. You must also provide yourself with a set of tools,--gimlets, hammers, planes, saws, gouges, files, nails, screws, and such articles of use.

The bench is composed of a platform or top, supported by four stout legs; supplied with a bench hook; this ought to be fitted in tight, so as to move up and down with a hammer only. The use of it is to keep any wood steady you may have to plane; the bench screw is used for keeping any wood firm and steady you may have to saw, which is to be put in the grip and screwed tight. Sometimes the edges of wood require to be planed, and then the wood is put in the grip or cheeks of the bench and held tight while you plane it. Make holes in the side of the bench, for the insertion of a movable pin to support the end of the board you have to plane or saw, which is not in the screw. The height of your bench should be about 2 feet 8 inches. The common length is from 10 to 12 feet, and the breadth about 3 feet 6 inches.

The jack plane is the first to be used. It is about 17 inches in length, and is used to take the rough parts from a piece of wood. It should be held steadily by fixing the right hand at the handle, and the left over the top and side, and pushed forward on the wood, when the knife will take off a shaving which runs through the hole, and falls on the side. In using the plane the endeavor should be to take off a clean shaving, which is done by using the instrument uniformly and steadily over every surface to be planed.

There is another kind of plane, called the trying plane, having a double top or handle. It is used to regulate and smooth to a higher degree, the surface of the wood that had previously been smoothed from the rough by the jack plane. Its length is about 22 inches, and it is broader than the jack plane. There is another plane called the _long_ plane, which is used for facing a piece of stuff, which it does with the greatest exactness; its length is about 2 feet 4 inches. There is also the joiner’s plane, which is the longest of all the planes, being 30 inches long. But the most handy of the planes to the boy carpenter is the smoothing plane. It is the last plane used in joining, and gives the utmost degree of smoothness to the surface of a piece of finished work; it is about 7 inches in length, the sides of the stock are curved, and resemble in figure a coffin; it is used in a similar way to the other.

SAWS.

There are many kinds of saws, but the most useful one is what is called the “hand saw.” It has a blade or plate about 28 inches long; the teeth of which are so formed as to allow you to cut the wood crossways as well as lengthways. The handle of the saw is made so as to allow a full yet free grasp of the hand, either for a pull or a thrust.

The _panel saw_. This saw has a plate nearly of the same size as a hand saw, and is used for cutting very thin boards, which the rough teeth of the hand saw would not cut through without breaking them.

The _tenon saw_ is of a different shape to the others, and is made to cut across the grain of the wood so as to leave the ends nicely even, that it may fit to the piece it is joined to, which is called a shoulder, being that part which comes in contact with the fiber of the wood. To do this it requires that the teeth should be much smaller, and they are therefore placed so close as eight or ten to the inch, according to the length of the blade.

The _dovetail saw_. There is another most useful saw it would be of advantage for the young carpenter to have, namely, the dovetail saw. It is about 9 inches long, and contains at least fifteen teeth in the inch. It is used for cutting the dovetails of boxes. Its plate is very thin, and it requires some care in using. It has a back for the purpose of strength, formed of a thin piece of brass or iron, let in so as to give the blade the requisite firmness necessary in using it.

The _compass saw_. The plate of this kind of saw is very narrow, and not more than one inch wide at the broadest part, gradually diminishing to about a quarter of an inch at the lower end. It is about 15 inches in length, and used for cutting a piece of wood into a circular form, and the plate being narrow allows it to follow the foot of the compass to a very small diameter.

The _keyhole saw_. The keyhole saw is much smaller than the above. It is used for cutting short curves, small holes, &c., such as a keyhole. The handle is the same form as that of the chisel, a small slit being cut through from end to end. It has a screw on one side, in order that the blade may be set to any length, according to the circumference of the hole to be cut.

THE SPOKE SHAVE.

This is a very useful tool. It is employed for smoothing the edges of round pieces, or other ends requiring to be shaved down. It is a narrow plane made of boxwood, and has generally a steel blade let into it to cut; it is used by taking hold of each end with a hand, and moving it to and fro over the wood to be shaved down.

STOCK AND BITS.

There are about thirty-six bits to a set, all of different shapes and sizes; but our young friends need not get quite so many; if they provide themselves with a couple of a medium size, this will be sufficient, such as the center bit and the auger bit. The center bit will cut holes varying from a quarter of an inch to three quarters of an inch in diameter, and is used by pressing the knob end against the chest, and twirling the center part round with the hand. It cuts a hole very clean, leaving it quite smooth inside. The auger bit is for the same purpose, and is used in the same manner. Another bit, called the taper shell bit, is used for making holes wider, and is a very useful implement.

HOW TO MAKE A WHEELBARROW.

One of the handiest things in a garden is a wheelbarrow, and one of the prettiest for the young carpenter to exercise his ingenuity upon. To make one, take a wide plank or board about an inch and a quarter thick. Proceed to your bench, and having fitted it to its proper position, take your jack plane and plane off the rough, next use your smoothing plane to make it smooth. Then take your pencil and draw upon its side the figure of a wheelbarrow. Then take your compass saw and cut round the marks you have made: to do this you will have to fix your board in the screw of your bench. When this is done take your spoke shave, and shave the edges all round till they are very smooth and even, and you have one side of your barrow. Lay this on another piece of board, and mark the shape of it with your pencil; cut and shave it exactly as you did the first side, so that when finished the two will exactly correspond; then cut a piece off another board for the back and front of the barrow, by the same method you cut the sides, and plane and finish them up in a similar way. Cut some tenons at the end of each exactly to correspond with the mortices on the sides, let them be a trifle larger than the mortices, so that they will drive in tight. Then cut the bottom out neatly, and nail it to the sides. Having proceeded thus far, cut out the legs of your barrow, and nail one on each side. Give each leg a shoulder for the sides to rest upon.

_To make the wheel._ Take a piece of board, and strike a circle upon it the size you wish your wheel to be of, and with the compass saw cut close round to the stroke; cut out a square hole in the center for the nave to join. Then get the blacksmith to put an iron rim round the wheel to keep it from splitting, and a round pin in each side of the nave, and put a staple in each side of the barrow to keep the wheel in its place. Paint the whole of any color you choose, and you will have a wheelbarrow.

THE WAY TO MAKE A BOX.

First ascertain the size you wish your box to be of. Then cut off your stuff, but take care to cut it a quarter of an inch longer than the size of your box from outside to outside. Should you want it deeper or broader than the length of a deal, the widest of which is generally only eleven inches; suppose, for instance, you wish your box to be 18 inches deep, and you have only 9-inch deal to make it with, you will of course have to join two together, or make what is called in carpentering a _gluejoint_. First, then, after you have cut off your stuff, take your jack plane and “scuffle the rough off,” then put your board edgeways into the bench-screw, and take your trying plane or long plane to get the edge of the deals that are to be glued together perfectly straight and even; and lastly use the joiner plane, which will take off a nice uniform shaving of the whole length of the board. Proceed exactly in the same manner with the other board to be joined to the first. Then, after having made each thoroughly smooth, clap the two together and see if they will lie close in every part; if not you must plane them till they do, taking care to plane the edges perfectly square, or at right angles to the surface of the board, for if you are not careful in this particular, when your boards are glued together they will be of this form. When you have joined them properly for glueing, let your glue be nicely hot and not too thick, and hold both edges of the boards together so that you can with a brush put the glue on both at one time, put the two together very quickly, let one of them be in the bench-screw, and while there rub the other backwards and forwards until the glue sets, which it will soon do if well joined. Let the whole dry, and then the glued part will be as strong as any other part of the board.

After your sides, ends, bottom, and top are thus prepared, you must then plane them up nicely, so that they are perfectly smooth and straight. Use first the jack plane, then the trying plane. When this is done you have to proceed to a nice little job, namely, to dovetail the corners together so as to form your box. In this process much depends upon the planing and squaring of the stuff, for if you have not done this nicely the dovetailing will be very imperfectly performed. Assuming that everything has been well done, then take the two ends of the box, and see that each is perfectly square and true to the other. Then allow one-eighth of an inch more than the thickness of your sides, and set out the ends, squaring it over on both sides, which when the dovetails are cut out will form the inside of the box.

TO CUT THE DOVETAILS.

Take one “end-piece” of the box, and place it endways into the bench-screw, and mark out the dovetails on the edge of the board inside, then with your dovetail saw cut in into the marks down to the lines squared over on the flat side. Then with a chisel cut out that part of the wood that is crossed, and leave the other part, this being the part which will form the pins or tails. Then take one side of your box and lay it flat on the bench, the inside uppermost; then place the end you have cut on it, keeping the edges flush, and mark round the shape of the pins, which will leave their form on the side piece, the black places being the mortices which are to be cut out. In cutting out these you must be careful to cut within side of the stroke, so that the mortices will be a little smaller than the pins, which will admit of their being driven in quite tight, and will allow the glue to adhere to them (for you have to glue these when you fix them). When you have thus put the ends and sides together let them stand till the glue gets dry, then take your planes and plane the quarter of an inch off the pins which you allowed to be a little longer than the length of the box, and you have then made the body of your box.

THE BOTTOM OF THE BOX.

Cut your bottom the exact size of the box, nail the bottom on, and “get out” a piece of wood (by cutting and planing in the usual manner) to nail round so as to form a skirting to it, and at the same time hide the joints of the bottom; “get out” a similar piece of wood to nail round the top which will form the lid. Then get a pair of box joints and a lock, and having put them on by a stroke of your own ingenuity, you will have a “box.”

GALVANISM, OR VOLTAIC ELECTRICITY.

“To play with fire
They say is dangerous; what is it then
To shake hands with the lightning, and to sport
With thunder?”--TYLER.

Galvanism, or electricity of quantity, in contradistinction to frictional electricity, called electricity of intensity, owes its name to the experiments on animal irritability made in 1790 by M. Galvani, a professor of anatomy at Bologna. These experiments were suggested by the following circumstances.

ORIGIN OF GALVANISM.

It happened that the wife of Galvani, who was consumptive, was advised to take as an article of food some soup made of the flesh of frogs. Several of these creatures were killed and skinned, and were lying on the table in the laboratory close to an electrical machine, with which a pupil of the professor was making experiments. While the machine was in action, he chanced to touch the bare nerve of the leg of one of the frogs with the blade of the knife that he had in his hand, when suddenly the whole limb was thrown into violent convulsions. Galvani was not present when this occurred; but being informed of it, he immediately set himself to investigate the cause. He found that it was only when a spark was drawn from the prime conductor, and when the knife or any other good conductor was in contact with the nerve, that the contracting took place; and after a time he discovered that the effect was independent of the electrical machine, and might be equally well produced by making a metallic communication between the outside muscle and the crural nerve.

SIMPLE EXPERIMENT TO EXCITE GALVANIC ACTION.

If the young experimenter will obtain a piece of zinc of the size of half a dollar and place it on the top of his tongue, and place a half-dollar beneath it, and bring the edges of the half-dollar and zinc in contact in front of his tongue, he will notice a peculiar sensation in the nerves of this organ, and some taste will be imparted to his mouth at the moment of contact.

WITH METAL PLATES IN WATER.

If we take two plates of different kinds of metal, platinum (or copper) and zinc for example, and immerse them in pure water, having wires attached to them above, then if the wire of each is brought into contact in another vessel of water, a galvanic circle will be formed, the water will be slowly decomposed, its oxygen will be fixed on the zinc wire, and at the same time a current of electricity will be transmitted through the liquid to the platina or copper wire, on the end of which the other element of water, namely, the hydrogen, will make its appearance in the form of minute gas bubbles. The electrical current passes back again into the zinc at the points of its contact with the platina, and thus a continued current is kept up, and hence it is called a galvanic circle. The moment the circuit is broken by separating the wires the current ceases, but is again renewed by making them touch either in or out of the water. If a small quantity of sulphuric acid be added to the water, the phenomenon will be more apparent. The end of the wire attached to the piece of platinum or copper is called the positive pole of the battery, and that of the wire attached to the zinc the negative pole.

The current of electricity here generated will be extremely feeble; but this can be easily increased by multiplying the glasses and the number of the pieces of metal. If we take six such glasses instead of one, partially fill them with dilute sulphuric acid, and put a piece of zinc and copper into each, connecting them by means of copper wire from glass to glass through the whole series, a stronger current of electricity will be the result. The experimenter must be careful not to let the wire and zinc touch each other at the bottom of the tumblers, and must also remember that the copper of glass 1 is connected with the zinc of glass 2, and so on.

TO MAKE A MAGNET BY THE VOLTAIC CURRENT.

To effect this, make a connection between the poles of the above or any excited battery with the two ends of a wire formed into a spiral coil, by bending common bonnet-wire closely round a cylinder, or tube, of about an inch in diameter; into this coil introduce a needle or piece of steel wire, laying it lengthways down the circles of the coil. In a few minutes after the electric fluid has passed through the spiral wire, and consequently round the needle or wire, the latter will be found to be strongly magnetized, and to possess all the properties of a magnet.

EFFECTS OF GALVANISM ON A MAGNET.

If a galvanic current, or any electric current, be made to pass along a wire under which, and in a line with it, a compass is placed, it will be found that the needle will no longer point north and south, but will take a direction nearly across the current, and point almost east and west.

CHANGE OF COLOR BY GALVANISM.

Put a teaspoonful of sulphate of soda into a cup, and dissolve it in hot water; pour a little cabbage blue into the solution, and put a portion into two glasses, connecting them by a piece of linen or cotton cloth previously moistened in the same solution. On putting one of the wires of the galvanic pole into each glass, the acid accumulates in the one, turning the blue to a red, and the alkali in the other, rendering it green. If the wires be now reversed, the acid accumulates eventually in the glass where the alkali appeared, while the alkali passes to the glass where the acid was.

THE GALVANIC SHOCK.

If the ends of the wires of a small galvanic battery are connected with a proper electro-magnetic coil, which may now be purchased at a very cheap rate, and the wires from the coil be placed in separate basins of water, then, on dipping the fingers of each hand in the basin, a smart shock will be felt, with a particular aching accompanied with trembling. With a strong battery and larger coil this effect is felt as high as the shoulders. The shock will also be felt by simply holding the wires of a powerful galvanic battery, one in each hand, provided the hands be moistened with salt and water. Several persons may receive the shock from the battery and coil together by joining hands.

THE ELECTROTYPE.

The electro-galvanic current has in no case been more interestingly employed than in the process of electrotyping. It consists of a mode of obtaining the copy of coins, medals, engraved plates, and other objects, which may be easily illustrated.

HOW TO MAKE AN ELECTROTYPE APPARATUS.

Take an earthen jar and a porous tube; fill the tube with ten parts of water and one of sulphuric acid; put it into the jar, into which pour as much of a solution of sulphate of copper (blue vitriol) as will fill three parts of it; place in the tube a piece of zinc, to which a copper wire is soldered and bent round, so that one end be immersed in the sulphate of copper; and a deposit of the copper will be immediately formed upon the wire. If there be plenty of acid and water, so as to allow of the action enduring for a long time, this process will go on till it has deposited all the copper. This is the principle upon which electrotyping proceeds--a principle referable to electro-chemical decomposition.

TO OBTAIN THE COPY OF A COIN OR MEDAL.

Never place the original medal in the apparatus, or the deposited copper may adhere so tightly to it that the removal destroys the beauty of the medal. Having taken an impression in sealing-wax, cover the latter with black-lead, and attach a wire so that it is in contact with the black-lead. To the wire and cast thus arranged a piece of sheet or cast zinc, amalgamated with mercury, must be attached, and we are at once furnished with the materials for the battery, as the object to be copied supplies the place of the copper. The medal must always be placed horizontally. Now let the apparatus be charged with the solution, by pouring into the outer vessel a portion of the coppery solution, so that it will stand about an inch above the medal; then pour in the glass the dilute acid to the same height as the former; now introduce the zinc into the acid, and the object to be copied into the solution of copper, which will immediately be deposited on the medal, and when of a sufficient thickness may be taken off.

HEAT.

HEAT, OR CALORIC.

The chief agent in causing the repulsion or separation of the particles of bodies from each other is heat, or more correctly _caloric_, by which is understood the unknown _cause_ of the effect called heat. Philosophers are not agreed upon the nature of this wonderful agent. It pervades all nature, is the cause of nearly all the changes that take place both in organic and inorganic matter, and has great influence in the meteorological phenomena which we observe in the atmosphere that surrounds our planet. It appears to be intimately connected with light, electricity, and magnetism--subjects which the genius of Faraday and others have investigated, and by their discoveries brought us nearer to the knowledge of the real nature of these most wonderful forces.

Caloric, then, exists in all bodies, and has a constant tendency to equalize itself, as far at least as its outward manifestation, called temperature, is concerned; for if a _hot_ body be brought near colder ones, it will give up heat to them, until by its loss and their gain they all become of the same temperature; and this proceeds more or less rapidly, according as the original difference of temperature was greater or less. Some other circumstances also influence this equalization. The converse will take place on introducing a cold body among warmer ones, when heat will be abstracted from all the bodies within reach of its influence, until it has absorbed sufficient caloric to bring its own temperature to an equality with theirs. This is the true explanation of the apparent production of _cold_. When, for instance, an iceberg comes across a ship’s course, it appears to _give out_ cold, whereas it has abstracted the heat from the air and sea in its neighborhood, and they in turn act upon the ship and everything in it, until one common temperature is produced in all the neighboring bodies.

It does not follow that the bodies thus equalized in temperature contain equal quantities of caloric; far from it. Each body requires a particular quantity of caloric to raise its temperature through a certain number of degrees; and such quantity is called its _specific_ caloric. A pound of water, for instance, will take just twice as much caloric as a pound of olive oil, to raise its temperature through the same number of degrees; the _specific_ caloric of water is therefore double that of oil. Mix any quantity of oil at 60 deg. of temperature with an equal weight of water at 90 deg., and you will find the temperature of the mixture to be nearly 80 deg., instead of only 74 deg. or 75 deg., showing that while the water has lost only 10 deg. of caloric, the mixture has risen 20 deg. If the oil be at 90 deg., and the water at 60 deg., the resulting temperature will be only 70 deg., or thereabouts, instead of 75 deg., the mean; thus, here the hot oil has lost 20 deg., while the mixture has risen only 10 deg.; the water, then, contains at the same temperature _twice_ as much caloric as the oil; its specific caloric is _double_ that of the oil. This mean temperature does result when equal weights of the same body at different temperatures are mixed together.

The sensations called heat and cold are by no means accurate measures of the real temperature of any substances, for many causes influence these sensations, some belonging to the substances themselves, others to the state of our organs at the time. Every one has remarked that metals in a warm room feel warmer, and in a cold room colder than wooden articles, and these again than woolen or cotton articles of dress or furniture; this arises from metals being what is termed better _conductors_ of heat than wood, and this better than wool, &c., that is, they give out or absorb caloric more rapidly than these last. Some philosophers, wishing to ascertain how much heat the human body could endure, had a room heated with stoves, every crevice being carefully stopped, until the temperature rose so high that a beefsteak placed on the table was sufficiently cooked to be eaten. They were dressed in flannel, and could with impunity touch the carpets, curtains, &c., in the room; but the iron handles, fire-irons, and all metallic substances, burnt their fingers; and one who wore silver spectacles was obliged to remove them to save his nose. The fallacy of our sensations may be easily shown by taking two basins, placing in one some water at 100 deg., in another some water at as low a temperature as can easily be procured--hold the right hand in one, the left in the other, for a few minutes, and then mix them, and place both hands in the mixture; it will feel quite _cold_ to the hand that had been in the hotter water, and _hot_ to the other.

In order to arrive at a correct estimate of the temperature of bodies, instruments are made use of called thermometers, or measurers of heat, which show increase or diminution of temperature by the rising or falling of a column of some fluid in a tube of glass, one end of which is expanded into a bulb, and the other hermetically sealed. This effect is produced by the expansion or swelling of the fluid as caloric is added to, and its contraction when caloric is abstracted from it. Colored spirits of wine, or quicksilver, are the most usual thermometric fluids, and the tube containing them is fixed to a wooden or metallic frame, on which certain divisions are marked, called degrees.

That in general use in America is called Fahrenheit’s from the name of the person who first introduced that particular scale. In this thermometer, the point at which the mercury in the tube stands when plunged into melting ice, is marked 32 degrees, and the distance between that point and the point to which the mercury rises in boiling water is divided into 180 equal parts, called degrees; so that water is said to boil at 212 degrees = 180 degrees + 32 degrees. There are two other scales of temperature used in different parts of the world, but it is not worth while to notice them here.

Not only do different bodies at the same degree of temperature contain very different quantities of caloric, but this also is the case with the same body in different forms. Ice, water, and steam are three forms of the same body, but ice at 32 degrees contains much less caloric than water at the same temperature, and water at 212 degrees contains much less caloric than steam (or water in a state of vapor) at that temperature.

Place in a jar any given quantity of snow, or small pieces of ice, at 32 degrees, and in another the same weight of water at 32 degrees, pour on each an equal weight of water at 172 degrees, and you will find that in the first case the ice will be melted, but the temperature will remain at 32 degrees, or thereabouts, while the temperature of the water in the other vessel will have risen to 100 degrees or thereabouts, being as near as possible the half of the excess of the temperature of the hot water, 140 degrees over that of the cold, namely 70 degrees added to 32 degrees, the original temperature. Now, what has become of the heat which was added to the ice, and is apparently lost?--it is _absorbed_ by the ice in its passage to the fluid state; so that water may be said to be a compound of ice and caloric.

Again, take 10 ounces of water at about 50 degrees, and add 1 oz. of water at 212 degrees, and the temperature of the mixture will be about 66 degrees; then condense some steam at 212 degrees into another 10 oz. of water until it has become 11 oz., and you will find the temperature will be nearly 212 degrees. Why does the ounce of steam at 212 degrees raise the temperature of the water so much higher than the ounce of water at the same temperature? Obviously because it contains hidden in its substance a vast quantity of caloric, not to be detected by the thermometer; in fact, that steam is a compound of _water_ and caloric, as water is a compound of _ice_ and caloric; and this caloric which exists, more or less, in all bodies without producing any obvious effect, is called _latent_ caloric, from the Latin verb _lateo_, to lie hid. The quantity of caloric thus absorbed, as it were, by various bodies, differs for each body, and for the same body in different forms, as mentioned above.

EXPANSION.

As a general rule, all bodies, whether solid, liquid, or gaseous, are expanded by caloric. This may be shown by experiments in each form of matter.

Have a small iron rod made, which when cold just passes through a hole in a plate of metal; heat it, and it will no longer pass; after a time the rod will return to its former temperature, and then will go through the hole as before. The rod increases in length as well as width; if you have a gauge divided into 1/100 of an inch, and place the rod in it when cold, noting its position, on heating it will extend to a greater length in the gauge, returning to its former place when cool.

The effect of caloric in causing fluids to expand is actually employed as a measure of quantity in the thermometer, the rise of the fluid in the tube when heated depending on the increased bulk of the fluid occasioned by the addition of caloric. The same fact is to be noticed every day when the cook fills the kettle, and places it on the fire. As the water becomes warmer it expands, that is, takes up more room than it did before, and the water escapes by slow degrees, increasing as the heat increases, up to the point of boiling, when a sudden commotion takes place from the condensation of a portion of the water into steam.

But it is in the form of vapor or gas (which, by the bye, is not the same thing), that the expansive force of caloric is most obvious. The gigantic powers of the steam-engine depend entirely on the tendency of vapor to expand on the addition of caloric; and this force of expansion appears to have no limit; boilers made of iron plates an inch or even more in thickness, and the buildings or ships containing them, having been torn to pieces and scattered in all directions by the expansive power of steam. Take a bladder and fill it about half-full of air, and tie the neck securely; upon holding it to the fire it will swell out and become quite tense from the expansion of the contained air.

The principal source of caloric is the sun, whose beams, diffused through all nature by the refractive property of the atmosphere, are the source of vitality both to vegetables and animals, and when concentrated by a large convex lens, produce the most intense heat, sufficient to light a piece of diamond, and melt platinum. Caloric is also produced or evolved by combustion, by friction, percussion, chemical combination, electricity, and galvanism.

The evolution of heat by friction may be witnessed daily in a thousand instances. Lucifer matches are lighted by rubbing the highly inflammable substances with which they are tipped against a piece of sand-paper. Nearly all savage people procure fire by rubbing a piece of hard wood violently against a softer piece. The axle-trees of steam-engines, and even of carriages, have been known to be so heated by friction as to endanger burning the carriage; and it is very usual to be obliged to pour a quantity of cold water on the iron axle of the carriages of an express train after an hour of constant and rapid work. If you merely rub the blade of a knife rapidly on a piece of wood it will become hot enough to burn your hand.

Percussion is merely a more energetic kind of friction, and is often resorted to by the blacksmith to light his furnace. He places a nail or other piece of soft iron on his anvil, and beats it rapidly with the hammer, when it becomes actually red hot. The production of sparks by striking flint against steel, or two pieces of flint one against the other, are familiar instances of heat produced by percussion.

One of the most powerful means of producing heat is the process of combustion.

Combustion, as the word imports, is the _burning together_ of two or more substances, a chemical union of oxygen generally with carbon and hydrogen in some shape or other. In our ordinary fires we burn coal, a hydro-carbon as it is called; and the gas which is now so universally used for the purpose of illumination, is a compound of the same bodies--so wax, tallow, oil of various kinds, both of animal and vegetable origin, are all hydro-carbons.

On the application of a sufficient heat, and a free access of atmospheric air, or of some other gas containing oxygen in a certain state of combination, these bodies take fire, and continue to burn either with flame, or a red or even white heat without flame, until they are consumed; that is, until they have entered into new combinations with the oxygen, and are converted into carbonic acid and water, the carbon forming the first product, the hydrogen the other.

The following experiment shows the productions of heat by chemical action alone. Bruise some fresh prepared crystals of nitrate of copper, spread them over a piece of tin foil, sprinkle them with a little water; then fold up the foil tightly as rapidly as possible, and in a minute or two it will become red-hot, the tin apparently burning away. The heat is produced by the energetic action of the tin on the nitrate of copper, taking away its oxygen in order to unite with the nitrate acid, for which, as well as for the oxygen, the tin has a much greater affinity than the copper has.

Combustion without flame may be shown in a very elegant and agreeable manner, by making a coil of platinum wire by twisting it round the stem of a tobacco-pipe, or any cylindrical body, for a dozen times or so, leaving about an inch straight, which should be inserted into the wick of a spirit-lamp; light the lamp, and after it has burnt for a minute or two extinguish the flame quickly; the wire will soon become red-hot, and, if kept from draughts of air, will continue to burn until all the spirit is consumed. Spongy platinum, as it is called, answers rather better than wire, and has been employed in the formation of fumigators for the drawing-room, in which, instead of pure spirits, some perfume, such as lavender water, is used; by its combustion an agreeable odor is diffused through the apartment. These little lamps were much in vogue a few years ago, but are now nearly out of fashion.

Experiments on combustion might be multiplied almost to any amount, but the above will be sufficient for the present. When we come to treat of the properties of the gases and some other substances, we shall have occasion to recur to this subject.

The production of caloric by chemical combination may be exhibited by mixing carefully one part of oil of vitriol with two of water, when sufficient heat will be produced to boil some water in a thin and narrow tube, which may be used as a rod to stir the mixture.

The production of heat by electric and galvanic agency belongs to another subject.

HYDRAULICS.

The science of Hydraulics comprehends the laws which regulate non-elastic fluids in motion, and especially water, etc.

Water can only be set in motion by two causes--the pressure of the atmosphere, or its own gravity. The principal law concerning fluids is, that they always preserve their own level. Hence water can be distributed over a town from any reservoir that is higher than the houses to be supplied; and the same principle will enable us to form fountains in a garden, or other place. Should any of our young readers wish to form a fountain, they may, by bringing a pipe from a water-tank, which should be at the upper part of the house, convey the water down to the garden. Then, by leading it through the earth, underneath the path or grass-plot, and turning it to a perpendicular position, the water will spring out, and rise nearly as high as the level of that in the tank. The pipe should have a faucet, so that the water may be let on or shut off at pleasure.

THE SYPHON.

The syphon is a bent tube, having one leg shorter than the other. It acts by the pressure of the atmosphere. In order to make a syphon act, it is necessary first to fill both legs quite full of the fluid, and then the shorter leg must be placed in the vessel to be emptied. Immediately upon withdrawing the finger from the longer leg, the liquor will flow.

THE PUMP.

The action of the common pump is as follows: When the handle is raised, the piston-rod descends, and brings the piston-valve--called the sucker, or bucket--to another valve, which is fixed, and opens inward towards the piston. When the handle is drawn down, the piston is raised, and, as it is air-tight, a vacuum is produced between the two valves; the air in the barrel of the pump, betwixt the lower valve and the water, then forces open the lower valve, and rushes through to fill up this vacuum; and the air in the pump being less dense than the external atmosphere, the water is forced a short way up the barrel. When the piston again descends to the lower valve, the air between them is again forced out by forcing open the upper valve; and when the piston is raised, a vacuum is again produced, and the air below the lower valve rushes up, and the water in consequence is again raised a little further. This operation continues until the water rises above the lower valve; at every stroke afterwards, the water passes through the valve of the descending piston, and is raised by it, on its ascent, until it issues out of the spout.

THE HYDRAULIC DANCER.

Make a little figure of cork, in the shape of a dancing mountebank, sailor, etc. In this figure place a small hollow cone, made of thin leaf brass. When this figure is placed upon any jet, such as that of the fountain recommended to be constructed, it will be suspended on the top of the water, and perform a great variety of amusing motions. If a hollow ball of very thin copper, of an inch in diameter, be placed on a similar jet, it will remain suspended, turning round and spreading the water all about it.

MAGNETISM.

The attractive power of the loadstone has been known from a very remote period. The natural magnet appears native in a gray iron ore in octahedral crystals, composed of 168 parts of iron, and 64 parts of oxygen. Its properties seem to have been studied in Europe during the dark ages and a directive power is alluded to by Cardinal James de Vitri, who flourished about the year 1200, who observed that it was indispensable to those who travel much by sea.

In modern times, the history as well as the nature of the magnet has engaged remarkable attention; and it has been determined beyond all dispute that the magnet was used by the Chinese under the name of the _tche-chy_ (directing stone) about 2604 years before Christ. It passed from them to the Arabs, and was first used in Europe after the crusades; and Ludi Vestomanus asserts that about the year 1500 he saw a pilot in the East Indies direct his course by a magnetic needle like those now in use.

TO MAKE ARTIFICIAL MAGNETS.

This may be done by stroking a piece of hard steel with a natural or artificial magnet. Take a common sewing needle and pass the north pole of a magnet from the eye to the point, pressing it gently in so doing. After reaching the end of the needle the magnet must not be passed back again towards the eye, but must be lifted up and applied again to that end, the friction being always in the same direction. After repeating this for a few times the needle will become magnetized, and attract iron filings, etc.

HOW TO MAGNETIZE A POKER.

Hold it in the left hand in a position slightly inclined from the perpendicular, the lower end pointing to the north, and then strike it smartly several times with a large iron hammer, and it will be found to possess the powers of a magnet, although but slightly.

TO SHOW MAGNETIC REPULSION AND ATTRACTION.

Suspend two short pieces of iron wire, so that they will hang in contact in a vertical position. If the north pole of a magnet be now brought to a moderate distance between the wires, they will recede from each other.

The ends being made south poles by induction from the north pole, will repel each other, and so will the north poles. This separation of the wires will increase as the magnet approaches them, but there will be a particular distance at which the attractive force overcomes the repulsive force of the poles, and causes the wires to converge.

NORTH AND SOUTH POLES OF THE MAGNET.

Each magnet has its poles, north and south--the north or south poles of one magnet repel the north and south pole of another. If a magnet be dipped in some iron filings, they will be immediately attracted to one end. Supposing this to be the north pole, each of the ends of the filings, not in contact with the magnet, will become north poles, while the ends in contact will by induction become south poles. Both will have a tendency to repel each other, and the filings will stand on the magnet.

POLARITY OF THE MAGNET.

The best method of proving this is to take a magnet or a piece of steel rendered magnetic, and to place it on a piece of cork by laying it in a groove cut to receive it. If the cork be placed in the center of a basin of water, and allowed to swim freely on its surface, so that it is not attracted by the sides of the basin, it will be found to turn its north pole to the north, and its south pole to the south, the same as the mariner’s compass. If you fix two magnets in two pieces of cork, and place them also in a basin of water, and they are in a parallel position with the same poles together, that is, north to north, and south to south, they will mutually repel each other; but if the contrary poles point to one another, as north to south, they will be attracted.

THE MAGNETIC FISH.

Fish are to be purchased at the toy-stores, by which the young “magnétique” may perform this experiment; they are made hollow, and will float on the water. In the mouth of each should be inserted a piece of magnetic wire. The angling rod is like any other rod, and has a silken thread for a line, and an iron hook also strongly magnetized. To catch the fish it is only necessary to put the hook in contact with the noses of the fish, and they will be taken without any bait.

THE MAGNETIC SWAN.

The figure of a swan should be cut in cork, and within its beak a small strongly magnetized piece of steel should be placed. The swan should then be covered with a coating of white wax, and fashioned further into the shape of a swan, and glass beads may be placed in its head for eyes. This should be placed in a small tub or large basin of water, and to make it swim about, you should place in a white stick about nine inches long a magnetic bar, on which the north and south poles are marked. If you wish to bring the swan towards you, present to him the north pole of the wand, if you wish it to retire, present the south pole, and thus you may direct the swan to any part you desire.

TO SUSPEND A NEEDLE IN THE AIR BY MAGNETISM.

Place a magnet on a stand to raise it a little above the table; then bring a small sewing needle containing a thread, within a little of the magnet, keeping hold of the thread to prevent the needle from attaching itself to the magnet. The needle in endeavoring to fly to the magnet, and being prevented by the thread, will remain curiously suspended in the air, reminding us of the fable of Mahomed’s coffin.

TO MAKE ARTIFICIAL MAGNETS WITHOUT THE AID EITHER OF NATURAL LOADSTONES OR ARTIFICIAL MAGNETS.

Take an iron poker and tongs, or two bars of iron, the larger and the older the better, and fixing the poker upright, hold to it with the left hand near the top by a silk thread, a bar of soft steel about three inches long, one-fourth of an inch broad and one-twentieth thick; mark one end, and let this end be downwards. Then grasping the tongs with the right hand a little below the middle, and keeping them nearly in a vertical line, let the bar be rubbed with the lower end of the tongs, from the marked end of the bar to its upper end about ten times of each side of it. By this means the bar will receive as much magnetism as will enable it to lift a small key at the marked end; and this end of the bar being suspended by its middle, or made to rest on a joint, will turn to the north, and is called its north pole, the unmarked end being the south pole. This is the method recommended by Mr. Caxton, in his process, which he regarded superior to those in former use, and of which a more detailed account will be found in his interesting volume.

HORSE-SHOE MAGNETS.

The form of a horse-shoe is generally given to magnetized bars, when both poles are wanted to act together, which frequently happens in various experiments, such as for lifting weights by the force of magnetic attraction, and for magnetizing steel bars by the process of double touch, for which they are exceedingly convenient. The following is the method of making a powerful magnetic battery of the horse-shoe form. Twelve bars or plates of steel are to be taken, and having been previously bent to the required form, that is, the horse-shoe shape, they are then bound together by means of rivets at their ends; before being finally fastened they are each separately magnetized and afterwards finally united.

Horse-shoe magnets should have a short bar of soft iron adapted to connect the two poles, and should never be laid by without such a piece of iron adhering to them. Bar magnets should be kept in pairs with their poles turned in contrary directions, and they should be kept from rust. Both kinds of magnets have their power not only preserved but increased, by keeping them surrounded with a mass of dry filings of soft iron, each particle of which will re-act by its induced magnetism upon the point of the magnet to which it adheres, and maintain in that point its primitive magnetic state.

EXPERIMENT TO SHOW THAT SOFT IRON POSSESSES MAGNETIC PROPERTIES WHILE IT REMAINS IN THE VICINITY OF A MAGNET.