Endless Amusement / A Collection of Nearly 400 Entertaining Experiments in Various Branches of Science; Including Acoustics, Electricity, Magnetism, Arithmetic, Hydraulics, Mechanics, Chemistry, Hydrostatics, Optics; Wonders of the Air-Pump; All the Popular Tricks and Changes of the Cards, &c., &c. to Which is Added, a Complete System of Pyrotechny; Or, the Art of Making Fire-works.

by Unknown

Then provide a small bag, with five or six divisions, like a lady's work-bag, but smaller. In one of these divisions put small square pieces of pasteboard, on which are written the numbers from 1 to 12. In each of the other divisions put twelve or more similar pieces, observing that all the pieces in each division must be marked with the same number. The needle being placed upon its pivot, and turned quickly about, it will necessarily stop at that point where the north end of the magnetic bar is placed, and which you previously know, by the situation of the small pin in the circular border.

You then present to any person that division of the bag which contains the several pieces on which is written the number opposite to the north end of the bar, and tell him to draw any one he pleases. Then placing the needle on the pivot, you turn it quickly about, and it must necessarily stop at that particular number.

The Magnetic Cards.

Draw a pasteboard circle; you then provide yourself with two needles, similar to those used in the foregoing experiment, (which you must distinguish by some private mark,) with their opposite points touched with the magnet. When you place that needle whose pointed end is touched, on the pivot described in the centre of the circle, it will stop on one of the four pips, against which you have placed the pin in the frame; then take the needle off, and, placing the other, it will stop on the opposite point.

Having matters thus arranged, desire a person to draw a card from a piquet pack, offering that card against which you have placed the pin of the dial, which you may easily do, by having a card a little longer than the rest. If he should not draw it the first time, as he probably may not, you must make some excuse for shuffling them again, such as letting the cards fall, as if by accident, or some other manœuvre, until he fix on the card. You then tell him to keep it close, and not let it be seen. Then give him one of the two needles, and desire him to place it on the pivot, and turn it round, when it will stop at the colour of the card he chose; then taking that needle off, and exchanging it, unperceived, for the other, give it to a second person, telling him to do the same, and it will stop at the name of the identical card the first person chose.

The Magnetic Orrery.

Construct a round box, Fig. 16, about eight inches diameter, and half an inch deep. On the bottom fix a circular pasteboard drawn like the figure. You are likewise to have another pasteboard, drawn exactly the same, which must turn freely in the box, by means of an axis placed on a pivot, one end of which is to be fixed in the centre of the circle.

On each of the seven smaller circles on the pasteboard, which you have fixed at the bottom of the box, place a magnetic bar, two inches long, in the same direction with the diameters of those circles, and their poles, in the situations expressed in the figure.

There must be an index like the hour hand of a dial, fixed on the axis of the central circle, by which the pasteboard circle in the box may be turned about; also a needle (forming in the figure the other hand) that will turn freely on the axis, without moving the circular pasteboard.

In each of the places where the word question is, write a different question; and in each of the seven circles where the planetary signs are, write two answers to each question; observing, that there must only be seven words in each question: for instance,