Robert Hooke demonstrated the superiority of single-lens over double-lens microscopes

December 16, 1677

Following up on his successful replication of Leeuwenhoek's observation of microscopic little animals in pepper water, Hooke addressed the magnifying and resolving powers of his microscopes. A week later, at the meeting on Thursday, December 23, 1677 (O.S.), he followed up with a single-lens microscope with better resolution


Birch's History of the Royal Society, vol. III, p. 348, December 6, 1677

Mr. HOOKE then shewed two microscopical experiments, which he had promised at the preceding meeting.

The first was a farther improvement of the compound microfcope, whereby he shewed those small insects in pepper-water very much more magnified and more clear than they appeared the day before; which was done by making the object-glass of a much smaller sphere than the last, which was viewed by several of the persons present.

The second was a new sort of single microscope, wherewith he exhibited to the president himfself, and afterwards to most of the members present, the same: little creatures swimming to and fro in the pepper-water contained in the fmall cane and made them so visible, that all, who looked through the said microscope, though they had not been accustomed to the use of glasses, yet discovered them so plainly, as to be able to discover their figures, magnitudes, and motions. And all concluded the appearance this way to be much more clear and distinct, than it was the other way by the double microscope, though that was one of the best of that kind.

Mr. HOOKE did not now give a description of his single microscope as having some farther improvements thereof to exhibit in some of the following meetings, undertaking to make the same to magnify objects a thousand times more than this; though this, considering the clearness, magnified about a thousand times more than the common microscopes. He was desired to prosecute these improvements with what expedition he could, and to prepare a letter to Mr. LEEWENHOECK against the next meeting.

Birch's History of the Royal Society, vol. III, p. 364, December 13, 1677

Mr. HOOKE then shewed the experiments appointed for this Meeting; and the first was an improvement of the single microscope, by which the little animals were exhibited much more magnified and very much plainer, though to some persons they seemed not so plain; the reason of which was to be ascribed to some otherwise imperceptible defects of the eye.