Page:Various Forces of Matter.djvu/21

Rh water and pour it in, you see that that side of the scales immediately goes down; that shows you (using common language, which I will not suppose for the present you have hitherto applied very strictly) that it is heavy, and if I put this additional weight into the opposite scale, I should not wonder if this vessel would hold water enough to weigh it down. [The Lecturer poured more water into the jar, which again went down.] Why do I hold the bottle above the vessel to pour the water into it? You will say, because experience has taught me that it is necessary. I do it for a better reason—because it is a law of nature that the water should fall towards the earth, and therefore the very means which I use to cause the water to enter the vessel are those which will carry the whole body of water down. That power is what we call gravity, and you see there [pointing to the scales] a good deal of water gravitating towards the earth. Now here [exhibiting a small piece of platinum ] is another thing which gravitates towards the earth as much as the whole of that water. See what a little there is of it—that little thing is heavier than so much water [placing the metal in opposite scales to the