The Balanced Stick.—A stick may be balanced and made to stand upright on the top of the finger by first taking the precaution to insert into its upper end, at about half an inch from that end, two knives, or two forks, or two other articles of equal weight. The stick should be of such a length that the ends of the knives are a trifle lower than the end of the stick when balanced.
A similar puzzle is to make a coin turn on its edge on the point of a needle, or to make a needle turn on its point on the head of a pin. For either of these puzzles, get a bottle, cork it tightly, and in the cork (which we will name B) place a needle or a pin; then take another cork (which we will call X) and cut a slit in one of its ends, so that the coin to be balanced will fit into the slit. If it is on a needle that the coin has to be balanced, force the needle into the cork B point outwards. Now stick two common steel forks, one on either side, into cork X, so that the forks hang downwards; place the coin in the slit of the last-mentioned cork and the edge of the coin on the point of the needle. If the needle is to be balanced on a pin, place the needle in the same manner; the weight of the forks will keep the toy balanced, and enable it to be safely spun round without danger of falling.
The Bridge of Knives (Fig. 2).—Three knives may be supported by their handles on the rims of three cups or glasses in the following manner:—Place the glasses in a triangle, each side of which shall be about equal in length to one of the knives to be balanced. The blade of the first knife should rest on the blade of the second by passing over it near to the point where the handle and blade are joined, the blade of the second passing in the same manner over the blade of the third, which is to be made to rest on the blade of the first. The handles being then properly placed on each one of the glasses forming the triangle, the bridge will be made, and it will be strong enough to bear a considerable weight.
Fig. 2.—The Bridge of Knives.
THE SQUARE AND CIRCLE PUZZLE.
Cut a square piece of cardboard, marked as shown in Fig. 3, into four pieces of equal size and similar shape, so that each piece shall contain three of the marks, and so that none of the marks are cut. Fig. 4 shows that the puzzle is solved by cutting the lines A from a quarter down on the left-hand side to half-way across, then down through the middle to three-quarters of the distance from the top, and then along to the opposite side of the card. The line B takes a corresponding course, being commenced on the top line at a quarter of the whole distance from the right-hand side.
Fig. 3.—Square and Circle—The Problem.