Part 2

Heads may be made to nod, faces to laugh; eyes may be made to roll, teeth to gnash; crocodiles may be made to swallow tigers; combats may be represented; but one of the most instructive uses of the slides is to make them illustrative of astronomy, and to show the ratio of the seasons, the cause of the eclipses, the mountains in the moon, spots on the sun, and the various motions of the planetary bodies and their satellites.

The Phantasmagoria.

Between the phantasmagoria and the magic lantern there is this difference: in common magic lanterns the figures are painted on transparent glass; consequently the image on the screen is a circle of light, having figures upon it; but in the phantasmagoria all the glass is opaque, except the figures, which, being painted in transparent colors, the light shines through them, and no light can come upon the screen except that which passes through the figure.

There is no sheet to receive the picture, but the representation is thrown on a thin screen of silk or muslin, placed between _the spectators and the lantern_. The images are made to appear approaching and receding, by removing the lantern further from the screen, or bringing it nearer to it. This is a great advantage over the arrangements of the magic lantern, and by it the most astonishing effects are often produced.

Dissolving Views.

The dissolving views, by which one landscape or scene appears to pass into the other while the scene is changing, are produced by using two magic lanterns, placed side by side, and that can be inclined towards each other when necessary, so as to mix the rays of light, proceeding from the lenses of each, together, which produces that confusion of images, in which one view melts, as it were, into the other, which gradually becomes clear and distinct.

How to Raise a Ghost.

The magic lantern or phantasmagoria may be used in a number of marvelous ways, but in none more striking than in raising an apparent specter. Let an open box, about three feet long, a foot and a half broad, and two feet high, be prepared. At one end of this place a small swing dressing-glass, and at the other let a magic lantern be fixed, with the lenses in a direction towards the glass. A glass should now be made to slide up and down in the groove to which a cord and pulley should be attached, the end of the cord coming to the lower part of the left hand side. On this glass the most hideous specter that can be imagined may be painted, but in a squat or contracted position, and when all is done, the lid of the box must be prepared by raising a kind of gable at the end of the box, and in its lower part an oval hole should be cut sufficiently large to suffer the rays reflected from the glass to pass through them. On the top or the box place a chafing-dish, upon which put some burning charcoal. Now light the lamp in the lantern, sprinkle some powdered camphor or white incense on the charcoal, adjust the slide on which the specter is painted, and the image will be thrown upon the smoke. In performing the feat the room must be darkened, and the box should be placed on a high table, that the hole through which the light comes may not be noticed.

To Imitate a Mirage.

Provide a glass tumbler two-thirds full of water, and pour spirits of wine upon it; or pour into a tumbler some syrup, and fill it up with water; when mixed, the object seen through it will be inverted.

Two-fold Reflections.

Provide a circular piece of glass, and with a common awl, moistened with spirits of turpentine, pierce the center of the glass; hold it encircled with the fingers and thumb in the sunshine, or the strong light of a lamp, when these striking effects will be produced: If the glass be _red_, the hole pierced in the middle will be reflected _green_; if the glass be _green_, the spot will be _red_; if _blue_, _orange_; and if _yellow_, _indigo_.

The Thaumatrope.

Cut out a piece of card-board of circular form, and affix to it six pieces of string, three on each side. Paint on one side of the card a bird, and on the other a cage, taking care to paint the bird upside down, or the desired effect will not be produced. When showing the toy, take hold of the center strings, between the forefinger and thumb, and twirl the card rapidly around, and the bird will appear snugly ensconced in its cage. The principle on which this effect is produced is, that the image of any object received on the retina or optic nerve is retained on the mind about eight seconds after the object causing the impression is withdrawn, being the memory of the object; consequently, the impression of the painting on one side of the card is not obliterated ere the painting on the other side is brought before the eye. It is easy to understand from this fact how both are seen at once. Many objects will suit the thaumatrope, such as a juggler throwing up two balls on one side, and two balls on the other; and according to the pairs of strings employed, he will appear to throw up two, three, or four balls; the body and legs of a man on one side, and the arms and head on another; a horse and his rider; a mouse and trap. But we leave it to the ingenuity of our readers to devise for themselves.

PNEUMATIC AMUSEMENTS.

The branch of the physical sciences which relates to the air and its various phenomena is called Pneumatics. By it we learn many curious particulars. By it we find that the air has weight and pressure, color, density, elasticity, compressibility, and some other properties with which we shall endeavor to make the young reader acquainted, by many pleasing experiments, earnestly impressing upon him to lose no opportunity of making physical science his study.

To show that the air has weight and pressure, the common leather sucker by which boys raise stones will show the pressure of the atmosphere. It consists of a piece of soft but firm leather, having a piece of string drawn through its center. The leather is made quite wet and pliable, and then its under part is placed upon the stone and stamped down by the foot. This pressing of the leather excludes the air from between the leather and the stone, and by pulling the string a vacuum is left underneath its center; consequently the weight of the air about the edges of the leather not being counterbalanced by any air between it and the stone, enables the boy to lift it.

The Magic Tumbler.

The air which for about forty miles surrounds our earth has a definite weight; and although we can neither see nor feel it, we are conscious of its presence by the momentary operation of breathing. The weight of a column of air one inch square, and forty miles high, is about fifteen pounds.

The reason why we are not crushed down by this enormous weight is because we are surrounded on all sides by it, and as the pressure of weight is equal all around, it becomes, as far as we are personally concerned, insensible.

That the air _does_ exert a definite pressure, in consequence of its weight, may be easily proved by any one with the above simple apparatus--only a tumbler and a sheet of paper. Fill a tumbler quite full of water, and carefully draw over its top a sheet of clean letter paper, and be careful to see that there are no bubbles of air in the water; place your hand over the paper while inverting it, and when the glass is mouth downward the water will be kept in, until the paper becomes wet through. The air pressing against the mouth of the tumbler is of greater weight than the contained water, and so, until some air can get in to supply the place of the water, it cannot fall out.

The Weight of the Air Proved by a Pair of Bellows.

Shut the nozzle and valve-hole of a pair of bellows, and after having squeezed the air out of them, if they are perfectly air-tight, we shall find that a very great force, even some hundreds of pounds, is necessary for separating the boards. They are kept together by the weight of the heavy air which surrounds them, in the same manner as if they were surrounded by water.

The Revolving Serpent.

This illustration represents an amusing and instructive experiment, which proves the ascension of heated air by rendering its effects visible, and it may also be used to test the direction of the currents in our rooms and dwellings. To construct one, a piece of card-board is taken and cut in the form of a spiral, and to give effect it may be painted to represent a serpent. Then prepare a stand, having a needle in its upper end, and suspend the serpent from its center on the needle. If this be now placed over a stove, or the tail of the serpent suspended by a bit of thread over a lamp, the heated air ascending through it will cause it to revolve in a very amusing manner. Two serpents may be made to turn in opposite directions, by pulling out one from the one side, and the other in the reverse direction, so that their heads may point toward each other when suspended.

To Put a Lighted Candle Under Water.

Procure a good-sized cork, or bung; upon this place a small, lighted taper; then set it afloat in a pail of water. Now, with a steady hand, invert a large drinking glass over the light, and push it carefully down into the water. The glass being full of air, prevents the water from entering it. You may thus see the candle burn _under_ water, and bring it up again to the surface, still alight. This experiment, simple as it is, serves to elucidate that useful contrivance called the diving-bell, being performed on the same principle.

The largest drinking-glass holds but half a pint, so that your diving light soon goes out for the want of air. As an average, a burning candle consumes as much air as a man, and he requires nearly a gallon of air every minute, so that, according to the size of the glass over the flame, you can calculate how many seconds it will remain alight; of course, a large flame requires more air than a small one. For this, and several other experiments, a quart bell-glass is very useful, but being expensive it is not found in every parlor laboratory: one is, however, easily made from a green glass pickle-bottle; get a glazier to cut off the bottom, and you have a bell-glass that Chilton would not reject.

To Place Water in a Drinking-Glass Upside Down.

Procure a plate, a tumbler, and a small piece of tissue or silver paper. Set the plate on a table, and pour water in it up to the first rim. Now slightly crumple up the paper, and place it in the glass; then set it on fire. When it is burnt out, or rather just as the last flame disappears, turn the glass quickly upside down into the water. Astonishing! the water rushes with great violence into the glass! Now you are satisfied that water can be placed in a drinking-glass upside down. Hold the glass firm, and the plate also. You can now reverse the position of the plate and glass, and thus convince the most skeptical of the truth of your pneumatic experiment. Instead of burning paper, a little brandy or spirits of wine can be ignited in the glass; the result of its combustion being invisible, the experiment is cleaner.

AMUSEMENTS IN MECHANICS.

There is no subject so important as mechanics, as its principles are founded upon the properties of matter and the laws of motion; and, knowing something of these, the tyro will lay the foundation of all substantial knowledge.

The properties of matter are the following: Solidity (or impenetrability), divisibility, mobility, elasticity, brittleness, malleability, ductility and tenacity.

The laws of motion are as follows:

1. Every body continues in a state of rest, or uniform rectilineal motion, unless affected by some extraneous force.

2. The change of motion is always proportionate to the impelling force.

3. Action and reaction are always equal and contrary.

Experiment of the Law of Motion.

In shooting at “taw,” if the marble be struck “plump,” as it is called, it moves forward exactly in the same line of direction; but if struck sideways, it will move in an oblique direction, and its course will be in a line situated between the direction of its former motion and that of the force impressed. It is called the resolution of forces.

Balancing.

The center of gravity in a body is that part about which all the other parts equally balance each other. In balancing a stick upon the finger, or upon the chin, it is necessary only to keep the chin or finger exactly under the point which is called the center of gravity.

The Balanced Coin.

It seems to be an astounding statement that a quarter, or other piece of money, can be made to spin on the point of a needle. To perform this experiment, procure a bottle, cork it, and in the cork place a needle. Now take another cork and cut a slit in it, so that the edge of the coin will fit into the slit; next place two forks in the cork, and placing the edge of the coin on the needle, it will spin around without falling off. The reason is this: that the weight of the forks projecting as they do so much below the coin, brings the center of gravity of the arrangement much below the point of suspension, or the point of the needle, and therefore the coin remains perfectly safe and upright.

The Spanish Dancer.

The laws which govern the motion of bodies are capable of many pleasing illustrations, and the example which we now give of causing rotary motion is very interesting and easily performed.

Take a piece of card, and cut out a little figure, and paste or gum it in an erect position on the inside of a watch-glass. Then procure a black japanned waiter, or a clean plate will do, and, holding it in an inclined position, place the figure and watch-glass on it, and they will, of course, slide down. Next let fall a drop of water on the waiter, place the watch-glass on it, and again incline the waiter, and instead of the watch-glass sliding down, it will begin to revolve. It will continue to revolve with increasing velocity, obeying the inclination and position of the plane, as directed by the hand of the experimentalist. The reason of this is, in the first place, in consequence of the cohesion of the water to the two surfaces, a new force is introduced, by which an unequal degree of resistance is imparted to different parts of the watch-glass in contact with the waiter, and, consequently, in its effort to slide down, it revolves. Again, if the drop of water be observed, it will be seen that it undergoes a change of figure; a film of water, by capillary action, is drawn to the foremost portion of the glass, while, by the centrifugal force, a body of water is thrown under the under part of it. The effect of both these actions is to accelerate the motion, or, in other words, to gradually increase the speed.

The Mechanical Bucephalus.

The illustration of the horse furnishes a very good solution of a popular paradox in mechanics: Given, a body having a tendency to fall by its own weight; required, how to prevent it from falling by adding to it a weight on the same side on which it tends to fall. Take a horse in an erect position, the center of gravity of which is somewhere about the middle of its body. It is evident, therefore, that were it placed on its hinder legs, on a table, the line of its direction, or center, would fall considerably beyond its base, and the horse would fall on the ground; but to prevent this, there is a stiff wire attached to a weight or bullet, connected with the body of the horse, and by this means a horse prances on a table without falling off; so that the figure that was incapable of supporting itself, is actually prevented from falling by adding a weight to its unsupported end. This seems almost impossible, but when we consider that in order to have the desired effect, the wire must be bent, and the weight be further under the table than the horse’s feet are on it, the mystery is solved, as it brings the total weight of bullet and horse in such a position that the tendency is rather to make it stand up than to let it fall down.

The Revolving Image.

This little figure may be made to balance itself amusingly. Get a piece of wood, about two inches long; cut one end of it into the form of a man’s head and shoulders, and let the other end taper off to a fine point. Next furnish the little gentleman with a pair of wafters, shaped like oars, instead of arms, but they must be more than double the length of his body; stick them in his shoulders, and he is complete. When you place him on the tip of your finger, if you have taken care to make the point exactly in the center, he will stand upright. By blowing on the waiters he may be made to turn around very quickly. It is explained by the reasons that were given in the experiment of the “balanced coin.”

The Bridge of Knives.

Place three glasses in the form of a triangle, and arrange the handles of three knives upon them. Nos. 1, 2, and 3, the blade of No. 1 over that of No. 2, and that over No. 3, which rests on No. 1. The bridge so made will be self-supported.

The Parlor Boomerang.

The boomerang is a weapon used by the savages of Australia. By them it is made of a flat piece of hard wood. The peculiarity of this instrument is, that in whatever direction it is thrown, it will return to the place from whence it started, in a curve. The Australian aborigines use it with great dexterity, making it travel around a house and return to their feet, or they can throw it on the ground so that it will fly into the air, form a perfect arc over their heads, and strike them on the back. This curious instrument can be made in miniature, and is a very amusing toy for the parlor.

Get a piece of tolerably stiff cardboard, and cut from it a figure resembling a boomerang.

The next thing is to propel it through the air so that it will return to your feet; to do this, lay the boomerang on a flat book, allowing one end to project about an inch; then, holding the book to a slight angle, strike the projecting end of the boomerang with a piece of stick, or heavy pen-holder, when it will fly across the room and return to your feet.

The Balanced Turk.

A decanter or bottle is first obtained, and in its cork is placed a needle; on this is balanced a ball of wood, having a cork or wooden figure cut out, standing on the top. From the ball project two wires, bent semicircularly, having at their extremities two bullets. Push the bullets, and the whole will turn around on the needle, the figure standing upright all the while; and, twist it about from side to side as much as you like, it will always regain its erect position. The two bullets in this case cause the center of gravity to fall below the ball on which the figure is placed, and, in consequence, as the center of gravity always assumes the lowest position, it cannot do so without making the figure stand erect, or, in other words, until the bullets themselves are equally balanced. Any boy may whittle one of these toys out with a jack-knife.

The Complacent Vizier.

Among the novelties which scientific investigation has added to our toys, are several figures which will raise themselves upright when thrown down, and regain the erect position, notwithstanding their equilibrium is disturbed. The figures themselves are made of the pith of elder trees, or any other very light substance. Each is placed on half a bullet, or may be made to stand on its head, by making its cap of lead. Their appearance is very droll when they are moved about, as they seem every moment to be falling over, and yet continually right themselves. The philosophy of this is, that the center of gravity being in the base, and always trying to assume the lowest position, it keeps the figures upright. However much the equilibrium is disturbed, it will always try to regain its original position.

ARITHMETICAL AMUSEMENTS.

As the principal object of these articles is to enable the young reader to learn something in his sports, and to understand what he is doing, we shall, before proceeding to the curious tricks and feats connected with the science of numbers, present him with some arithmetical aphorisms, upon which most of the following examples are founded:

Aphorisms of Number.

1. If two even numbers be added together, or subtracted from each other, their sum or difference will be an even number.

2. If two uneven numbers be added or subtracted, their sum or difference will be an even number.

3. The sum or difference of an even and an uneven number added or subtracted will be an uneven number.

4. The product of two even numbers will be an even number, and the product of two uneven numbers will be an uneven number.

5. The product of an even and uneven number will be an even number.

6. If two different numbers be divisible by any one number, their sum and their difference will also be divisible by that number.

7. If several different numbers, divisible by 3, be added or multiplied together, their sum and their product will also be divisible by 3.

8. If two numbers divisible by 9, be added together, their sum of the figures in the amount will be either 9 or a number divisible by 9.

9. If any number be multiplied by 9, or by any other number divisible by 9, the amount of the figures of the product will be either 9 or a number divisible by 9.

10. In every arithmetical progression, if the first and last term be each multiplied by the number of terms, and the sum of the two products be divided by 2, the quotient will be the sum of the series.

11. In every geometric progression, if any two terms be multiplied together, their product will be equal to that term which answers to the sum of these two indices. Thus, in the series:

1 2 3 4 5 2 4 8 16 32

If the third and fourth terms, 8 and 16, be multiplied together, the product, 128, will be the seventh term of the series. In like manner, if the fifth term be multiplied into itself, the product will be the tenth term; and if that sum be multiplied into itself, the product will be the twentieth term. Therefore, to find the last, or twentieth term of a geometric series, it is not necessary to continue the series beyond a few of the first terms.

Previous to the numerical recreations, we shall here describe certain mechanical methods of performing arithmetical calculations, such as are not only in themselves entertaining, but will be found more or less useful to the young reader.

To Find a Number Thought of.

FIRST METHOD.

EXAMPLE. Let a person think of a number, say 6 1. Let him multiply by 3 18 2. Add 1 19 3. Multiply by 3 57 4. Add to this the number thought of 63

Let him inform you what is the number produced; it will always end with 3. Strike off the 3, and inform him that he thought of 6.

SECOND METHOD.

EXAMPLE. Suppose the number thought of to be 6 1. Let him double it 12 2. Add 4 16 3. Multiply by 5 80 4. Add 12 92 5. Multiply by 10 920

Let him inform you what is the number produced. You must then, in every case, subtract 320; the remainder is, in this example, 600; strike off the 2 ciphers, and announce 6 as the number thought of.

THIRD METHOD.

Desire a person to think of a number--say 6. He must then proceed:

EXAMPLE. 1. To multiply this number by itself 36 2. To take 1 from the number thought of 5 3. To multiply this by itself 25 4. To tell you the difference between this product and the former 11 You must then add 1 to it 12 And halve this number 6

Which will be the number thought of.

FOURTH METHOD.

Desire a person to think of a number--say 6. He must then proceed as follows: