Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 Excerpt: ...the experiment of the physical laboratories called the cup of Tantalus, which is based on the principle of the siphon. Pour some water into the egg-shell, which will mount until it attains the level of the thimble; then the siphon is set in action, and all the water makes a lively exit through the straw. You may continue to pour your water at regular intervals into the shell, but your audience will be convinced that by some mysterious means it empties itself with equal regularity. The Flattening of the Earth at the Poles.--Its Rotundity at the Equator. By the simple apparatus which we are about to construct, you can explain to a child how the earth, by 210 FLATTENING OF THE EARTH AT THE POLES. revolving on its axis, has become flattened at the poles and rounded at the equator. For the earth was a doughy mass before it became solid, and the velocity of its revolutions while in this doughy state gave it its present shape. Let us take the well-known toy called the spinner, or snorer, as shown in the illustration, which consists of a small shield or circular piece of pasteboard, with two holes near the centre, through each of which a thread is passed, and which is made to spin on these threads by pulling them back and forth with your hands. The rapidity of rotation thus obtained is what causes the change which we are trying to explain. Stick into the thick part of the pasteboard four stems of wire (hairpins broken in two will suit perfectly), in such a manner that these stems be placed at the extremities of the two diameters of the pasteboard, at right angles to each other. Now make two circular rings of strong paper, about an inch wide, and with a diameter a little larger than the circular pasteboard. Put these one into the other, at right angles, and glue tog...
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