will know at once that it is the centre of gravity—that point in me where the whole gravitating force of my body is centred, and which I thus bring in a line over my foot.
Here is a toy I happened to see the other day, which will, I think, serve to illustrate our subject very well. That toy ought to lie something in this manner (fig. 5). And would do so if it were uniform in substance; but you see it does not, it will get up again. And now philosophy comes to our aid; and I am perfectly sure,
Fig. 5.  |
Fig. 6.  |
without looking inside the figure, that there is some arrangement by which the centre of gravity is at the lowest point when the image is standing upright; and we may be certain when I am tilting it over (see fig. 6) that I am lifting up the centre of gravity (a), and
