Theatrum naturae et artis

The third is: gravity can be diminished without any sensible loss of matter, as we see in a glass globe, filled with peas and water and properly sealed with wax. In this, the weight will be different after eight days than it was at the beginning.

The fourth is: there are bodies whose parts are heavy, but the whole is light, as evidenced by pumice, whose parts descend under water, yet the whole floats; indeed, even with metals, if they are treated appropriately.

4.

Next, we consider violent motion, as it is mainly exhibited through certain coils (a).
(a) And indeed in the Cartesian candelabrum, as it was commonly called, equipped with coils pushing the candle upward, and another machine, which boasts a stronger coil, teaching how to project fire-balls without gunpowder.

5.

Motion on inclined planes also reveals itself in various machines. (a)
(a) Such as the Archimedean screw, which serves for filling ships with water and emptying lakes, and at the same time shows how we can ascend by descending.