Here is a curious experiment in equilibrium (Fig. 1), which is easily done. Two forks are stuck into a cork, and the cork is placed on the brim of the neck of a bottle. The forks and the cork form a whole, of which the centre of gravity is fixed over the point of support. We can bend the bottle—empty it even, if it contains fluid—without the little construction over its mouth being in the least disturbed from its balance. The vertical line of the centre of gravity passes through the point of support, and the forks move with the cork, which serves as their support, thus forming a movable structure, but much more stable than one is inclined to suppose. This curious experiment is often performed by conjurers, who inform their audience that they will undertake to empty the bottle without disturbing the cork.

If a woodcock has been served for dinner, or any other bird with a long beak, take off the head at the extreme end of the neck; then split a cork so that you can insert into it the neck of the bird, which must be tightly clipped to keep it in place; two forks are then, fixed into the cork exactly as in the preceding example, and into the bottom of the cork a pin is inserted. This little contrivance is next placed on a piece of money, which has been put on the opening of the neck of the bottle, and when it is fairly balanced we make it spin round by pushing one of the forks as rapidly as we please, but as much as possible without any jerk. We then see the two forks, and the cork surmounted by the woodcock's head, turning on the slender pivot of a pin (Fig. 2). Nothing can be more comical than to witness the long beak of the bird turning round and round, successively facing all the company assembled round the table, sometimes with a little oscillation, which gives it an almost life-like appearance.