Theatrum naturae et artis

(a) Which we do not wish to be the entity of the body itself, or its quality, or the magnetism of the earth, or effluvia through electric attraction, or a conservative virtue—which is illustrated by Guericke original: "Gverkio" - likely referencing Otto von Guericke with a sulfur globe—depressing the body; but we establish the air together with the aether (the gravitation of which is shown to the eye in solar rays, exciting smoke in a bell jar through a burning glass and depressing it again) as the causes of gravity, without excluding the disposition of each body.

(b) The first of which is: not every heavy thing descends: as can be seen in a thermometer, where the suspended liquid does not descend; in a certain type of siphon; in brass and marble spheres, in which the lower one, together with an attached weight, hangs as if glued to the upper one; wax pellets not descending below water, which nevertheless afterwards exhibit various phenomena by their descent and ascent.

The second is: gravity can be increased without any sensible access of matter: as we observe in a small glass figure, which, at my whim in water, now descends, now ascends.