( 844 ) 
CMonfieur Leewenhoecks Letur to the PuhUfin, wkerew feme 
account U given of the manner of his observing fogre^t 4 num- 
her of little Animals in divers forts of rvater, as rvas deliver d 
in the next foregoing traSf : Englijb'd out of Dutch. 
SIR, 
I Received your Letters of the iitb and 7.2th thelafl: 
month ; and I was not a little pleafed , that my Obferva- 
tions about Water had not difpleafed your learned Philofo- 
phers. Nor do I wonder,they could not well apprehcnd,how 
1 had been able to obferve fo vaft a number of living Creatures 
in one drop of water, that being very hard to conceive with- 
out an ocular infpcilion. Meantime I never affirmed, that I 
could determine a certain number of thofe Animals living in 
water, but I generally laid , that I imagined I faw fo many ; 
Not that I doubt of the truth of the thing, butufea certain 
number for an uncertain, and that not by exceeding thenum* 
ber, but by leflTeningit. I thusorder mydivifionof theWater 
and the enumeration of tht animalcula : I fuppofe, that a drop 
of Water doth equal a Pea in bignefs ; and I take a little quan- 
tity of water, of a round figure, as big as a Millet-grain ; this 
1 reckon to be the one an(i ninetieth part of a pea : for when 
the axis of aMillcc-feed maketh f, that of a Pea will make 4^7 
whence it follows, that the grain of a Millet is at leaft the 
9Uh part of a Pea, accordin^g to the received Rules of Mathd* 
maticians. This final 1 quantity of Water I gather up into a very 
flender glafs-pipe, dividing by this means that little water into 
2 5 or 30 parts, of which I obferve one part after another , atid 
ftew the fame to others. 
Amongfl: other Speflators, I fliew'd it to a not ordinary per- 
fon,of great fagacity and an excellent fighr,wh© judged with me, 
that in f^part of water, equalling thebipnefsof a Millet-feedj 
lie faw more than a thoufand living Animals: which when he; 
highly wondred at, he wondr^d much more, when I faid , 1; 
faw in it two or three kinds of much fmaller Animals befides,; 
which did not appear to him, becaufe I Taw ^hem by atiothef 
Microfcope, which I ftill referve to my fclf alone. Hence it 
ismanifeftjtbat, if in the i part of one Millet -feed there are 
feen 1000 , there may be feen 30000 in one fuch whole feed, 
and conftquently in a drop of water, which is 9 1 times bigger 
than 
