Page:Various Forces of Matter.djvu/31

them together as one mass, and philosophers have discovered that there is a certain point in the middle of the whole collection of shots that may be considered as the one point in which all their gravitating power is centred, and that point they call the centre of gravity; it is not at all a bad name, and rather a short one—the centre of gravity. Now suppose I take a sheet of pasteboard or any other thing easily dealt with, and run a bradawl through it at one corner a (fig. 3) and Mr. Anderson hold that up in his hand before us, and I then take a

Fig. 3.

Fig. 4.

piece of thread and an ivory ball, and hang

c 2