By referring to certain plates in this volume, which reproduce illustrations from Robert Hooke's work on the microscope, it will be seen that quite a high degree of effectiveness had been attained.

And it should be recalled that Antony von Leeuwenhoek, whose death took place shortly before Newton's, had discovered such micro-organisms as bacteria, had seen the blood corpuscles in circulation, and examined and described other microscopic structures of the body.
XIV.

PROGRESS IN ELECTRICITY FROM GILBERT AND VON GUERICKE TO FRANKLIN We have seen how Gilbert, by his experiments with magnets, gave an impetus to the study of magnetism and electricity.

Gilbert himself demonstrated some facts and advanced some theories, but the system of general laws was to come later.

To this end the discovery of electrical repulsion, as well as attraction, by Von Guericke, with his sulphur ball, was a step forward; but something like a century passed after Gilbert's beginning before anything of much importance was done in the field of electricity.
In 1705, however, Francis Hauksbee began a series of experiments that resulted in some startling demonstrations.