Page:Various Forces of Matter.djvu/39

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GRAVITATION IN MASSES.
27

large one, they would also fall in the same time; for if an avalanche fall from the mountains, the rocks, snow and ice, together falling towards the earth, fall with the same velocity, whatever be their size.

I cannot take a better illustration of this than that of gold leaf, because it brings before us the reason of this apparent difference in the time of the fall. Here is a piece of gold leaf. Now if I take a lump of gold and this gold leaf, and let them fall through the air together, you see that the lump of gold—the sovereign, or coin—will fall much faster than the gold leaf. But why? They are both gold, whether sovereign or gold leaf. Why should they not fall to the earth with the same quickness? They would do so, but that the air around our globe interferes very much where we have the piece of sold so extended and enlarged as to offer much obstruction on falling through it. I will, however, show you that gold leaf does fall as fast when the resistance of the air is excluded—for if I take a piece of gold leaf and hang it in the centre of a bottle, so that the gold, and the bottle, and the air within shall all have an equal chance of falling, then the gold leaf will