More than 1,250,000 tons of coal are consumed yearly by the famous Krupp works at Essen, Westphalia, commenced in 1810 by Peter Friedrich Krupp, and now in the possession of Herr Friedrich Krupp, member of the Reichstag. The establishment consists, according to the Eisen Zeitung, of two steel works, with 15 Bessemer converters; four steelworks, with Siemens-Martin open hearth furnaces; iron, steel and brass foundries; puddling, melting, reheating and annealing furnaces; draw benches; a hardening and tempering department; file manufactory; rolling mills for plates, rails and tires; railway spring and wheel manufactory; steam hammers, forges, axle turning shop, boiler shop, engineering and repair shop. Besides the above and many other departments, at Essen, connected with the making of cannons, there are steel works at Annen, in Westphalia, three collieries in Westphalia, besides participation in several others; 547 iron mines in Germany; various iron mines at Bilboa, in Spain; four iron works, including one at Duisburg, one at Engers, one at Neuwid, and one at Sahn; various quarries of clay, sandstone, etc.; four steamers, and artillery ground at Meppen, Hanover. The property owned extends over 974 hectares, and the number of hands employed in the mines and steelworks is 25,301. There are altogether 1,500 furnaces of various kinds, 3,000 engines and machine tools, 22 roll trains, 111 steam hammers, 2 hydraulic presses, 263 stationary boilers, 421 steam engines, representing together a force of 33,139 horse power, and 430 cranes, including travelers, having a collective lifting power of 4,662 tons. The total length of the shafting is 8.8 kiloms. (5½ miles), and that of railways, standard and small gage, 85 kiloms. (53 miles), worked by 32 regular trains, with 33 locomotives. The annual consumption of coal amounts to 1,253,161 tons, and that of lighting gas to 12,000,000 cubic meters, while there are 573 arc and 1,804 incandescent electric lamps.
The Chain and the String.—To the extremity of a string about 18 in. in length attach a chain about 15 in. in length, the extremities of which are united. Holding the string vertically between the fingers, give it a rapid rotary motion. The chain will first open out as seen at A of the figure. Upon increasing the velocity of rotation, it will be thrown out farther and farther until it finally forms a circle in a horizontal plane. In this motion, the string forms a sort of conoidal surface, distended by centrifugal force.
The Chain and the String
B of the figure gives the exact aspect that the arrangement offers to the eye during the revolution. In the same way, a penholder attached by one of its extremities to a string assumes an almost horizontal position.
This experiment illustrates the principle of centrifugal force.
A Coin Rolling Upon a Parasol.—In treatises upon physics and mechanics inertia is defined as follows: No particle of matter in a state of rest possesses within itself the power of putting itself in motion; or, if it be moving, of bringing itself to a state of rest.
As an example of this principle, we may recall here the trick performed by certain jugglers, and that consists in making a coin roll over the top of a Japanese paper parasol. The parasol is revolved very rapidly, and, to the eyes of the spectator, the coin seems to remain immovable. It is, in reality, the parasol that revolves under the coin.
Breaking Stones with the Fist.—It is through the live force acquired, or inertia at rest, that stones are broken by a blow of the fist. This experiment is performed as follow: The right hand being properly bandaged with a handkerchief, the stone to be broken is taken with the left and allowed to rest upon a larger stone or upon an anvil. Then the stone to be broken is struck with the right fist, while care is taken to raise it a slight distance above the anvil just before the fist touches it. The stone then takes on the velocity of the fist that strikes it, and coming into violent contact with its support, is very promptly broken.
As simple as this experiment is, it always surprises the spectators.
Experiment on Inertia.—It is not impossible to remove from a table set for a guest a large napkin employed in lieu of a table cloth, without disarranging the objects placed upon it. To this effect, it suffices to give the napkin a quick horizontal jerk in stiffening the edges held by the hands.
We recommend our readers to try this experiment only with table ware of slight value, for one cannot always be sure of succeeding immediately. Tinware may be employed very advantageously.
The Dice and the Dice Box.—A dice box and two dice are held in the hand, and the question is to throw one die into the air and catch it in the box. This is not difficult, but the difficulty is to cause the second to enter, for if this be thrown into the air, the first, which is already in the box, will fly into the air likewise and fall outside. In order to make the second enter while the first is already in the box, it must not be thrown into the air, but the hand and the box must be quickly lowered in freeing it, so that the first die, which is in the box, shall be at a less height than the second, which is in the fingers. The dice fall less quickly than the hand and the box.
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