Fig. 38.
84. Compass. Fig. 38 shows a magnetized sewing-needle floated upon a cork. The needle may be permanently fastened to the cork with a few drops of melted paraffine.
85. Compass. Fig. 39. With a sharp knife make a cut part way through a flat cork. Into the cut push a short length of magnetized watch-spring. In the illustration the spring is shown partly removed from the cut. Float the cork.
86. Compass. Fig. 40. Stick a pin, P, into a pasteboard, cork, or wooden base, B. Bend a piece of stiff paper double, as shown, and then stick through it, on each side, a magnetized sewing-needle, S N. The north poles of the needles should be at the same end of the paper. Why? Balance the paper upon the pin-pivot, and see it fly around to the north and south.
| Fig. 39. | Fig. 40. | Fig. 41. |