Martin Folkes' article about Leeuwenhoek's microscopes published in Philosophical Transactions

January 1, 1724

Martin Folkes' article Some account of Mr. Leeuwenhoek's curious Microscopes, lately presented to the Royal Society is published in Philosophical Transactions. The volume is dated 1722, but it did not appear until after Leeuwenhoek's death.

an excerpt from the article:

The legacy consists of a small Indian Cabinet, in the Drawers of which are 13 little Boxes or Cases, each containing two Microscopes, handsomely fitted up in Silver, all which, not only the Glasses, but also the Apparatus for managing of them, were made with the late Mr. Leeuwenhoek's own Hands: Besides which, they seem to have been put in Order in the Cabinet by himself, as he designed them to be presented to the Royal Society, each Microscope having had an Object placed before it, and the Whole being accompany'd with a Register of the same, in his own Hand-Writing, as being desirous the Gentlemen of the Society should, without Trouble, be enabled to examne many of those Objects, on which he had made the most considerable Discoveries. ...

Their Powers of magnifying are different, as different Sorts of Objects may require; and, as on the one Hand, being all ground Glasses, none of them are so small, and consequently magnify to so great a Degree, as some of those Drops, frequently us'd in other Microscopes; yet, on the other, the Distinctness of these very much exceeds what I have met with in the Glasses of that Sort; and this was what Mr. Leeuwenhoek ever principally propos'd to himself, rejecting all those Degrees of magnifying in which he could not so well obtain that End; for he informs us in one of his Letters, where he is speaking of the excessive Praise some give to their Glasses on this Account, that although he had above Forty Years had Glasses by him of an extraordinary Smallness, he had made but very little Use of them; as having found, in a long Course of Experience, that the most considerable Discoveries were to be made with such Glasses as, magnifying but moderately, exhibited the Object with the most perfect Brightness and Distinction.

... It may be a Caution to us, that we do not rashly condemn any of this Gentleman's Observations, tho' even with his own Glasses, we should not immediately be able to verify them ouselves. We are under very great Disadvantages for want of the Experience he had, and he has himself put us in Mind, more than once, that those who are the best skill'd in the Use of Magnifying-Glasses, may be misled, if they give too sudden a Judgment upon what they see, or 'till they have been assured from repeated Experiments. But we have seen so many, and those of his most surprizing Discoveries, so perfectly confirm'd, by great Numbers of the most curous and judicious Observers, that there can surely be no Reason to distrust his Accuracy in those others, which have not yet been so frequently or carefully examin'd.


Phil. Trans. Vol. 32, no. 380, 446-453.