190 LEEUWENHOEK AND HIs ‘“‘ LITTLE ANIMALS ”’ 
Archimedes showeth that as 14 is to 11, so is the square 
of the diameter to the content of a circle.’ 
14—11—8 
8 704 
64 14 507 square inches for my body’s thick- 
11 ness. 
704 
600 _hairbreadths in a length of one inch. 
33 diameters of the very little vessels in 
our bodies for one hairbreadth (that 
is, reckoning the little vessels in our 
bodies 1089 times thinner than a 
hair) 
gives 19800 little vessels in a length of one inch. 
19800 
gives 392040000 little vessels to a square inch. 
50 square inches for the body’s thickness 
gives 19602000000 vessels in the thickness of the body. 
If we now suppose that the little vessels bear the same 
proportion to the bodies of the little animals, as those in 
us do to our bodies; then, in order to compare the very 
little vessels of the animalcules with the thickness of a 
sand-grain, the number given above must still be multi- 
plied by 300 (since, as already said, a sand-grain is 300 
times thicker than an animalcule). 
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slender than the apparently heavily-built man depicted in his portraits. 
Moreover, the statement is not easy to reconcile with the later record that 
at this date he weighed over 11 stone (ef. p. 222 infra). 
* Nowadays we usually find the area of a circle by 77°; but “/y X d’ is 
obviously the same thing, and Prof. D’Arcy Thompson informs me that it is 
actually in this form that the proposition is found in the Circuli Dimensio of 
Archimedes.—It is highly improbable, of course, that L. had ever studied 
the writings of this great mathematician. 
