The first experiment is a very simple one. Partly fill the bottle with water; then take one of the corks, make a slit in one end in the direction of its length, into which insert a coin. Next stick two forks into the cork, on opposite sides and near the other end, at angles of about 30deg. With the forks so placed, as balance-weights, it is an easy matter to balance the coin upon one edge of the mouth of the bottle, as in Fig. 1. With a steady hand it is also possible to execute the effective termination shown in the lower portion of the same illustration--_i.e._, to slope the bottle gradually so as to pour out a glass of the contents, retaining the while the coin in equilibrium upon the neck of the bottle. 2.--A COIN BALANCED ON A NEEDLE. [Illustration] By a slight variation of the previous arrangements the coin may be balanced edgeways upon a needle-point and made to rapidly revolve thereupon. Fig. 2 shows the experiment in operation. 3.--THE BALANCED PIN. To balance a pin upon a needle would seem rather a formidable undertaking; but by an application of the same principle no considerable difficulty is encountered. Stick the pin into another cork in position corresponding to that of the coin in the first experiment, into which also fix two forks as in the previous examples. With a little care it is then quite practicable to rest the head of the pin upon the point of the needle, where it will remain balanced as in Fig. 3. [Illustration] 4.--A PIN OR NEEDLE BALANCED HORIZONTALLY. [Illustration] By another variation of the conditions it is possible to balance the pin upon the needle-point in a horizontal position and to make it revolve thereon in that situation. The only alteration necessary to the preparations already made is to substitute for the two forks two ordinary pocket-knives. By bending the handles of the knives at an angle to the blade, the pin may be sustained in a horizontal position. Or, by the substitution of a long needle for the pin, the forks may be retained as balance-weights, as in the previous example and as shown in the present illustration. The pin may be rested upon the needle-point as in the figure, and by a gentle touch of the finger may be set revolving. In time, by reason of the relative differences in hardness of the two metals, the commencement of a tiny hole will be drilled by the sharp steel point of the needle in the softer brass of the pin, and if the motion be continued for a sufficient length of time a hole will ultimately be an accomplished fact. 5.--THE SPINNING PLATE. [Illustration]