He also first pointed out that the motions of the heavenly bodies must be looked upon as a mechanical problem, and was almost within grasping distance of the exact theory of gravitation, himself originating the idea of making use of the pendulum in measuring gravity.

Likewise, he first proposed the wave theory of light; although it was Huygens who established it on its present foundation.
Hooke published, among other things, a book of plates and descriptions of his Microscopical Observations, which gives an idea of the advance that had already been made in microscopy in his time.

Two of these plates are given here, which, even in this age of microscopy, are both interesting and instructive.

These plates are made from prints of Hooke's original copper plates, and show that excellent lenses were made even at that time.

They illustrate, also, how much might have been accomplished in the field of medicine if more attention had been given to microscopy by physicians.