Robert Hooke failed to demonstrate "minute animals" in pump water. The Royal Society read the testimonials from people in Delft.

November 11, 1677

Using a variety of thin pipes, Hooke failed to demonstrate "minute animals" in pump water. He was asked to try again, with pepper water, as Leeuwenhoek had used, and with thinner pipes. The members agreed with Leeuwenhoek's assertion that the curvature of the pipe helped the magnification. Hooke was asked to use "some better microscope", too.

At this meeting, the Royal Society read the testimonials from the citizens of Delft who corroborated Leeuwenhoek's claims.


Birch's History, vol. III, p. 346, 347, 1 November 1677 (O.S.) in London:

There were produced a great many exceedingly small and thin pipes of glass of various sizes, some ten times as big as the hair of a man's head; others ten times less. These were made in order to try a conjecture of Mr. HOOKE, propounded to the Society, that the discoveries, affirmed to be made by Mr. LEEWENHOECK, were made by help of viewing with a good microscope such small pipes containing the liquor or water, in which those multitudes of exceedingly small insects or animals wriggling among each other are discovered; for that he alledged, that the said pipes being filled with liquors became themselves as it were magnifying glasses, augmenting such bodies, as swim in the said liquor, on those parts of the said pipes, which are farthest from the eye-glass; for the pipes themselves being looked on by the help of a very good microscope, are made very large and conspicuous; and they again augmenting the opposite parts by the refraction on their cylindrical surfaces double the effect of a single microscope, as was very evident. But notwithstanding this there was no discovery made in the liquor, that was made use of, which was only common pump-water, of any such minute animals. It was therefore ordered, that against tbe next meeting pepper-water should be provided, and some better microscope than that made use of, that the truth of Mr. LEEWENHOECK'S assertions might, if possible, be experimentally examined, of which he had produced so many testimonies from such, as affirmed themselves to be eye-witnesses.

After this Mr. LEEWENHOECK'S papers, which had been produced at the preceding meeting, were read; four of which were testimonials of two ministers, a public notary, and other persons of good credit to the number of eight, of the truth of his former assertions concerning the almost incredible number of small animals wriggling in pepper-water; some of whom estimated, that they saw ten thousand, others thirty thousand, others forty-five thousand little animals in a single drop of water as big as a millet-seed. The two other contained an account of same farther observations made by him with his microscope; one written in Dutch, and the other the same translated into Latin by him; the particulars of which were, 1. That the cause of the blackness of Ethiopians is from the constitutions of the pores, that will not admit light. 2. Of young eels found in eels, and of other lesser within those young ones. 3. That the blood of eels consists of small long sharp pipes; whence he conceived to proceed the noxious qualities of eels blood to the eyes. 4. Of the eggs' and manner of generation of [illegible ], their shapes in the eggs, and their manner of exclusion, how he differs from SWAMMERDAM, &c. 5. That He had sent over the attestation of eight several credible persons, who had attested the truth of his assertions.

After the reading of these papers, Mr. HOOKE was ordered to return the Society's thanks to Mr. LEEWENHOECK, and to endeavour to procure farther discoveries from him by holding correspondence with him. And upon this occasion much discourse arose concerning infects bred in water. Mr. HENSHAW affirmed, that he in May had often taken up with a China comb out of standing water great numbers of small infects not visible but by the help of a microscope, which were thereby found to be like a perch.

For HOOKE’s more complete account of the events related to L. during the meetings of November 1677, see The Hooke Folio Online, CELL/RS/HF_107-111.