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has left us, which are indeed extraordinary', when 
confidered as the Firft almoft of their Kind : Let us 
reverence him as our great Mafter in this Art. But 
the World fince muft have been ftrangely ftupid, if 
it could have improved nothing, where there was 
room for fo much Improvement. I do not mean as 
to the Glafles ( for the Goodnefs of thefe before us, 
gives juft Reafon to believe he might have others as 
excellent as can perhaps be ever made); but as to 
the Strudure of the Inftrument they are fet in, and 
the Manner of applying Objeds to them. And I 
fahfy moft People will allow, that herein great Im- 
provements have been made : And it is with Pleafure 
I find, that a large Share of the Credit belongs 
to our own Countrymen. 
One thing alone (yvhich, when flightly confidered, 
may appear but trifling) has conduced greatly to 
thefe Improvements } and that is, the making ufe of 
fine transparent Mufcovy Talc or Ifinglafs , placed in 
Sliders, to inclofe Objeds in. Had Mr. Leeuwenhoek 
known this Way, it would have faved him a vaft 
deal of Expence and Trouble: For then, we may 
reafonably fuppofe, inftead of making an intire and 
feparate Microfcope for every Objed he was defirous 
to keep by him in Readinefs to fhew his Friends, he 
would probably have fecured his Objeds in Sliders, 
as we at prefent do, and have contrived fome fuch 
Means as ours, of fcrewing his feveral Glafles of 
different magnifying Powers, occafionally, to one 
and the fame Inftrument, and of applying his Sliders 
to which of them he judged beft. A few good 
Glafles, gradually magnifying one more than other, 
would, by fuch a Method, have anfwered all the 
U u u 2 Pur- 
