LETTER 19. 23 mMARCH 1677 169 
drop of water. Yet I can’t wonder at it, since ’tis 
difficult to comprehend such things without getting a 
sight of ’em. 
But I have never affirmed, that the animals in water 
were present in such-and-such a number: I always say, 
that I imagine I see so many. 
My division of the water, and my counting of the 
animalcules, are done after this fashion. I suppose that 
a drop of water doth equal a green pea in bigness;* and 
I take a very small quantity of water, which I cause to 
take on a round figure, of very near the same size as a 
millet-seed. ‘This latter quantity of water I figure to 
myself to be the one-hundredth part of the foresaid drop : 
4s for I reckon that if the diameter of a millet-seed 
45° be taken as 1, then the diameter of a green 
225 -pea must be quite 43. This being so, then a 
_— + quantity of water of the bigness of a millet-seed 
20m”, maketh very nearly the sz part of a drop, ac- 
cording to the received rules of mathematicks 
00 ©. (8.-« Shown. in the margin). This amount of 
~ 91] Bas water, as big as a millet-seed, I introduce into 
a clean little glass tube (whenever I wish to 
millet-seeds 
equalone let some curious person or other look at it). 
Sie This slender little glass tube, containing the 
(vobmme)- “water, I divide again into 25 or 30, or more, 
parts; and I then bring it before my microscope, by 
means of two silver or copper springs, which I have 
attached thereto for this purpose, so as to be able to 
place the little glass tube before my microscope in any 
desired position, and to be able to push it up or down 
according as I think fit. 
I showed the foresaid animalcules to a certain 
Gentleman, among others, in the manner just described ; 
and he judged that he saw, in the zoth part of a quantity 
'In Letter 96, L. tells us that his standard “ green pea”’ weighed 8 grains. 
See p. 214 infra. 
