Stránka:book 1913.djvu/238

2l6 The Book of Woodcraft A HOME-MADE COMPASS If you happen to have a magnet, it is easy to make a compass. Rub a fine needle on the magnet; then on the side of your nose. Then lay it gently on the surface of a cup full of water. The needle will float and point north. The cup must not be of metal. AN INDIAN CLOCK, SHADOW CLOCK OR SUNDIAL To make an Indian shadow clock or sundial, prepare a smooth board about fifteen inches across, with a circle ^______^___^__^_^^^__^ divided by twenty-four ~. I*. ] ^ rays into equal parts. Place it on a level, solid post or stump in the open. At night set the dial so that the twelve o'clock line points ex- actly north, as deter- mined by the Pole Star and nail it down. Then, fix a stick or pointer with its upper edge on the centre and set it exactly pointing to the Pole Star (a b) ; that is, the same angle as the latitude of the place, and fix it there immov- ably; it may be necessary to cut a notch (c) in the board to permit of a sight line. The hours eight at night to four next morning may as well be painted black. As a time- piece, this shadow clock will be found roughly correct.