ON NATURAL MOTIONS caused by Gravity

Chapter 2. On the moments A measure of the tendency of a weight to cause rotation around a pivot. of heavy bodies floating in a fluid.

...it would push the drum, and therefore it ought to be turned downward from point A toward G, since it is hindered by no restraint. Therefore, the tympanum A hollow drum or cylinder used in mechanical experiments. could always be revolved from A toward G. This is because the same cause of rotation original: "vertiginis" would always persist: namely, the pendulum CD would be perpetually preserved in a horizontal position, and therefore it would always press and tread upon the surface of the drum at AG. For this reason, it seems possible to achieve the perpetual motion The hypothetical machine that runs indefinitely without an external energy source, which Borelli here argues is impossible. of the aforementioned drum by such a device.

This, as I said, seems to offer such great probability that none of the many friends to whom I communicated this invention suspected a fallacy to lie hidden in it. Nonetheless, although I never cared to put this device into practice, I do not fear to pronounce absolutely that the perpetuity of motion cannot be achieved by this way. I certainly cannot persuade myself that heavy bodies ought ever to move spontaneously when they are able to descend not even a hair's breadth more than before, and cannot approach the center of the earth. Since, therefore, the common center of gravity D of both fluids is always retained and remains in the same horizontal plane ABCD, it seems to me altogether impossible that the wheel or drum AGBF should be turned from the direction of A toward G. Thus, although the common center of gravity D is distant from the fixed center of rotation...

A circular diagram representing a mechanical device or drum. It features a main outer circle labeled with points A (left), B (right), F (top), and G (bottom). A central vertical axis is labeled F, C (center), E, and G. A horizontal axis is labeled with D on the left and H on the right. The diagram illustrates a physical problem regarding the center of gravity and the possibility of perpetual motion in a fluid-filled or weighted drum.