Having an opportunity of acquainting myself with astronomy

I have in some of my foregoing observations discovered some new Motions even in the Earth it self, which perhaps were not dreamt of before

This depends upon three Suppositions

in 1658 or 1659 I continued and perfected the air-pump for Mr Boyle, having first seen a contrivance for that purpose made for the same honourable person by Mr Gratorix, which was too gross to perform any great matter.

a kind of solid or hardned froth, or a congeries of very small bubbles consolidated in that form, into a pretty stiff as well as tough concrete, and that each Cavern, Bubble, or Cell, is distinctly separate from any of the rest, without …

I shall explaine a Systeme of the World

all Cœlestial Bodies whatsoever, have an attraction or gravitating power towards their own Centers