[ 5 " 3 
The Sex he confeffes he could not diftinguifh, and 
adds, that it died in endeavouring to get clear of the 
Skin. 
Mr. Leeuwenhoeks ^ ry juftly expofes this romantic 
Difcovery, pretended to be made by this Speck of a 
Microfcope; and takes occafion therefrom to let us 
know, he does not think fuch minute Glades are fo 
much to be depended on as thofe of a larger Dia- 
meter. But there are fo many Degrees between the 
fmalleft Glafs we have of his, (whofe Focus is at ~ 
of an Inch) and this almoft invifible Point,* that we 
muft not infer from hence he ufed none of a Size 
between. Nay, this very Letter feems to imply the 
contrary ; for it tells us, that, in examining the Semen 
r virile , he made ufe of Eight or Ten Microfcopes 
of different magnifying Powers: But as all the Mi- 
crofcopes we have of his, have Obje&s fattened to 
them, and beddes have no Apparatus for Fluids, I 
think they could not probably be the fame he em- 
ployed for that Examination. May we not rather 
fuppofe he had Eight or Ten different Sizes of Mi- 
crofcopes, that magnified more than ours? For we 
know, Fluids require to be examinined by the greateft 
Magnifiers j and doubtlefs he made ufe of fuch for 
that Purpofe. 
There is no Advantage in employing a greater 
Magnifier for any Objett, than what ' is requifite to 
fhew the fame diftin&ly; but when the Objeft is 
exceedingly minute, the magnifying Power of the 
Glafs muft be proportionably great, or elfe it will be 
impoflible to fee the Objeft clearly. A Lens, (for 
Example) that fhews a whole Flea diftin&ly, mag- 
nifies 
