THE YEASTS CHAPMAN 301 



distinctness of these very much exceeds wliat I have met witli in the glasses 

 of that sort ; and this was what Mr. Leeuwenhoelv 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 extraor- 

 dinary 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. 



But however excellent these glasses may be judg'd, Mr. Leeuwenhoek's dis- 

 coveries are not entirely to be imputed to their goodness only : his own great 

 judgment and experience in the manner of using them, together with the 

 continual application he gave to that business, and the indefatigable industry 

 with which he contemplated often and long upon the same subject viewing it 

 under many and different circumstances, cannot but have enabled him to 

 form better judgments of the nature of his objects, and see farther into their 

 constitution, than it can be imagined any other person can do, that neither 

 has the experience, nor has taken the pains this curious author had so 

 long done. 



Nor ought we to forget a piece of skill, in which he very particulai'ly 

 excell'd, which was that of preparing his objects in the best manner, to be 

 view'd by the microscope ; and of this I am persuaded any one will be satisfied, 

 who shall apply himself to the examination of some of the same objects as do 

 yet remain before these glasses ; at least, I have my self found so much 

 difficulty in this particular, as to observe a very sensible difference between 

 the appearances of the same object, when apply'd by my self, and when 

 prepared by Mr. Leeuwenhoek, though view'd with glasses of the very same 

 goodness. 



I have the rather insisted upon this, as it may be a caution to us, that we 

 do not rashly condemn any of this gentleman's observations, though even with 

 his own glasses we should not immediately be able to verify them our selves. 

 We are under very great disadvantages for v.ant 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 

 curious 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. 



Upon the whole, it is to be hoped some of the society will pursue those 

 enquiries the late possessor of these microscopes was so deservedly famous for ; 

 and that as we have lost in Mr. Leeuwenhoek a most worthy member and a 

 most valuable correspondent, this last piece of his respect to the Royal Society 

 will not only enrich our repository but both encourage and enable some other 

 diligent observer to prosecute the same curious and useful discoveries. 



Unhappily the microscopes bequeathed to the Koj^al Society by 

 Leeuwenhoek have ceased to enrich its repository, since, when the 

 society removed to its present habitation, tlie miscroscopes disap- 

 peared in a very mysterious manner, and their whereabouts— if 

 indeed they still exist — has not been traced, even to the present day. 



