Visited by Thomas Molyneux on behalf of the Royal Society

February 13, 1685

In early February, Leeuwenhoek was visited by Thomas Molyneux (1661-1733, portrait on right), the brother of Edmond Halley's ally William Molyneux. Thomas was at the time a student in Leiden. Dobell notes that William visited Leeuwenhoek, too, but he did not know whether they visited together. If the older, more established William had been there, it is unclear why the younger student Thomas would have written his own account. In fact, William probably visited Leeuwenhoek separately in the summer of 1685.

Thomas reported his visit in a letter from Leiden dated February 13, to the secretary of the Royal Society, Francis Aston. It was read aloud at a February meeting.

His report on March 14 also included a paragraph on Leeuwenhoek, below.


Dobell gives the text of the original letter on p. 57. Birch's History, v. 4, p 365, has the version below, the spelling and punctuation copyedited by him. The original letter is in the Royal Society archives and a copy is in the Letter Book Original vol. 10 (1685-1686) p. 1.

I have hitherto delayed, answering your last, because I could not give you an account of Mynheer LEEWENHOECK; but last week I was to wait upon him in your name: he shewed me several things through his microscopes, which 'tis in vain to mention here, since he himself has sent you all their descriptions at large.

As to his microscopes themselves, those, which he shewed me, in number at least a dozen, were all of one sort, consisting only of one small glass, ground, (this I mention because 'tis generally thought his microscopes are blown at a lamp, those I saw, I am sure, are not) placed between two thin flat plates of brass, about an inch broad, and an inch and a half long. In these two plates there were two apertures, one before, the other behind the glass, which were larger or smaller, as the glass was more or less convex, or as it magnified. Just opposite to these apertures on one side was placed sometimes a needle, sometimes a slender flat body of glass or opaque matter, as the occasion required, upon which, or to its apex, he fixes whatever object he has to look upon; then holding it up against the light, by help of two small screws, he places it just in the focus of his glass, and then makes his observations.

Such were the microscopes, which I saw, and these are they he shews to the curious that come and visit him; but besides these, he told me he had another sort, which no man living had looked through setting aside himself; these he reserves for his own private observations wholly, and he assured me they performed far beyond any, that he had shewed me yet; but would not allow me a sight of them, so all I can do is barely to believe, for I can plead no experience in the matter.

As for the microscopes I looked through, they do not magnify much, if anything, more than several glasses I have seen, both in England, and Ireland: but in one particular, I must needs say, they far surpass them all, that is in their extreme clearness, and their representing all objects so extrordinary distinctly, for I remember we were in a dark room with only one window, and the sun too, was then off of that, yet the objects appeared more fair and clear, then any I have seen through microscopes, though the sun shone full upon them, or though they received more then ordinary light by help of reflective specula or otherwise: So that I imagine 'tis chiefly, if not alone in this particular, that his glasses exceeds all others, which generally the more they magnify the more obscure they represent the object; and his only secret I believe, is making clearer glasses, and giving them a better polish then others can do.

I found him a very civil complaisant man, and doubtless of great natural abilities; but, contrary to my expectations, quite a stranger to letters, master neither of Latin, French or English, or any other of the modern tongues besides his own, which is a great hindrance to him in his reasonings uppon his observations, for being ignorant of all other mens thoughts, he is wholly trusting to his own, which, I observe, now and then lead him into extravagancies, and suggest very odd accounts of things, nay, sometimes such, as are wholy irreconsilable with all truth. You see, Sir, how freely I give you my thoughts of him, because you desired it.

A month later, Molyneux wrote the follow-up letter about Hermann, Swammerdam and "the Madman at Harlem". Birch dated the report as March 14; the copy in the Letter Book Original vol. 10 p. 49-50 dated it as March 16. About Leeuwenhoek, Molyneux wrote,

The Glasses Mr Lewenhoeck shew'd me magnified Objects no more then several other glasses I have seen before, & therefore discover nothing but what may easily be seen by help of other Microscopes, so an account of them would be no ways satisfactory ; 'tis only his owne privat Glasses which make those more then ordnary discoverys. I never heard he sold those glasses of his more common sort ; but I sha'nt returne suddenly into England, for I designe, to have stayd some while in France, & perhaps visite Italy before that time, so I ca'nt serve You in this particular."