Nature's Teachings: Human Invention Anticipated by Nature. J. G. WoodЧитать онлайн книгу.
until a new supply of air is forced into the chamber.
However dissimilar in appearance may be the cannon, rifle, pistol, or any other firearm, to the pea-shooter and its kin, the principle is exactly the same in all. It has been already mentioned that in the blow-guns the air is compressed by the exertion of human lungs, and in the air-gun the compression is achieved by human hands.
But with the firearm a vast volume of expansible gas is kept locked up in the form of gunpowder, gun-cotton, fulminating silver, or other explosive compound, and is let loose, when wanted, by the aid of fire.
In the illustration are represented on the right hand the blow-guns of America and Borneo, and below them is the cannon as at present made. On the left hand of the same illustration is seen a representation of a natural gun which has existed for thousands of years before gunpowder was invented, and very long before the savage of Borneo or America discovered the blow-gun.
It is the Archer-fish (Chœtodon), which possesses the curious power of feeding itself by shooting drops of water at flies, and very seldom failing to secure its prey.
There are several species of this very curious fish spread over the warmer parts of the world, and their remarkable mode of obtaining prey is very well known in all. There is, indeed, scarcely any phenomenon in Nature more remarkable than the fact of a fish being able to shoot a fly with a drop of water projected through its tubular beak, if we may use that expression for so curiously modified a mouth.
Indeed, so certain is the fish of its aim, that in Japan it is kept as a pet in glass vases, just as we keep gold fish in England, and is fed by holding flies or other insects to it on the end of a rod a few inches above the surface of the water. The fish is sure to see the insect, and equally sure to bring it down with a drop of water propelled through its beak.
It is worthy of remark that the same principle was once, though unsuccessfully, employed in the propulsion of carriages, under the name of the Pneumatic Railway. Some of my readers may remember the railway itself, or at all events the disused tubes which lay for so many years along the Croydon Railway. Speed was obtained, as I can testify from personal experience, but the expense of air-pumps and air-tight tubing was too great to be covered by the income, especially as the rats ate the oiled leather which covered the valves.
I find some little difficulty in arranging the subject which comes next in order. It might very properly be ranked among the Levers, which will be treated of in another chapter; or it might be placed among the examples of centrifugal force, together with the sling, the “governor” of the steam-engine, &c., all of which will be more fully described in their places. However, as we are on the subject of Projectiles, we may as well take it in the present place.
It is the Throwing-stick, by which the power of the human arm is enormously increased, when a spear is to be hurled. Perhaps the most expert spear-throwers in the world are to be found among the Kafir tribes of Southern Africa, and yet the most experienced among them could not make sure of hitting a man at any distance above thirty or forty yards. But the throwing-stick gives nearly double the range, and I have seen the comparatively slight and feeble Australian hurl a spear to a distance of a hundred yards, and with an aim as perfect as that of a Kafir at one-fourth of the distance.
The mode in which this feat is performed is shown in the accompanying diagram. Instead of holding the spear itself, the native furnishes himself with a “Throwing-stick.” This weapon varies greatly in shape and size, but a very good idea of its form, and the manner of using it, may be obtained from the accompanying illustration, which was drawn from the actual specimen as held by an Australian native.
The throwing-stick is armed at the tip with a short spike, which fits into a little hole in the but of the spear. The stick and spear being then held as shown in the illustration, it is evident that a powerful leverage is obtained, varying according to the length of the stick. I possess several of these instruments, no two of which are alike.
It is rather remarkable that among the Esquimaux a throwing-stick is also used, exactly similar in principle, but differing slightly in structure, the but of the spear fitting into a hole at the end of the throwing-stick. Wood being scarce among the Esquimaux, these instruments are mostly made of bone. I possess one, however, which is made of wood, beautifully polished, and adorned with a large blue stone, something like a turquoise, set almost in its middle. One of the most curious points in the formation of the Esquimaux weapon is, that the but is grooved and channelled so as to admit the fingers and thumb of the right hand. The average length of this instrument is twenty inches.
In New Caledonia the natives use a contrivance for increasing the power of the spear, which is based on exactly identical principles, though the mode of carrying them out is different. A thong or cord of some eighteen inches in length is kept in the right hand, one end being looped over the forefinger, and the other, which is terminated by a button, being twisted round the shaft of the spear. When the weapon is thrown, the additional leverage gives it great power; and it is a noteworthy fact that the sling-spear of New Caledonia has enabled us to understand the otherwise unintelligible “amentum” of the ancient classic writers.
Passing from Art to Nature, we have in the jaw of the serpent an exact type of the peculiar leverage by which the spear is thrown. If the reader will refer to the illustration, he will see that the lower jaw of the snake, instead of being set directly on the upper jaw, is attached to an elongated bone, which gives the additional leverage which is needful in the act of swallowing prey, after the manner of serpents.
In War and in Peace we have been long accustomed to shield the edges and points of our sharp weapons with sheaths, and even the very savages have been driven to this device. I have in my collection a number of sheathed weapons from nearly all parts of the world, and it is a remarkable fact that the Fan tribe, who are themselves absolutely naked, sheathe their daggers and axes as carefully as we sheathe our swords and bayonets. In some points, indeed, they go beyond us; for the most ignorant Fan savage would never think of blunting the edge of his weapon by sheathing it in a metal scabbard. Their sheaths are beautifully made of two flat pieces of wood, just sufficiently hollowed to allow the blade to lie between them, and bound together with various substances. For example, the sheaths of one or two daggers in my possession are made of wood covered with snake-skin, while others are simply wood bound with a sort of rattan. Even the curious missile-axe which the Fan warrior uses with such power is covered with a sheath when not in actual use.
The figure on the right hand of the illustration represents the heads of two spears of Waganda warriors. When they present themselves before their king, the warriors must not appear without their weapons, and it would be contrary to all etiquette to show a bare blade except in action. The sheath can be slipped off in a moment, but there it is, and any man who dared to appear before his sovereign without his weapon, or with an unsheathed spear, would lose his life on the spot, so exact is the code of etiquette among these savages.
The sheathed spears of Nature are shown in the same illustration. On the left is a side view of the piercing apparatus of the common Gnat.
In the middle is the compound piercing apparatus of the common Flea, with which we are sometimes too well acquainted, the upper figure showing the lancets and sheaths together, and the lower exhibiting them when separated.
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