[ 3^5 ] ~ ' 
do to the naked eye. And as the fingle microfcope 
has, like the fpeftacle, but one lens between the eye 
and the objeft, there is no reafon to fuppofe the 
one can deceive us more than the other. The 
compound, having a larger field, is more pleafant 
than the fingle microfcope for many purpofes ; but 
the fingle fhould be always preferred by thofe who 
wifii to afcertain the figures of minute bodies. It 
was this inftrument fupported on a fcroll, as deline- 
ated by Mr. Baker (Microfcope made eafy, plate II. 
chap. 3.) that has been ufed in thefe experiments 
and almoft all the obfervations were made with 
lenfes, as they are prepared by fome of our more 
fkilful workmen in London. One obfervation only 
was made by means of thofe globules made of glafs, 
which the ingenious Father de la Torre prefented 
to the Royal Society, and which they were fo 
obliging as to lend to me. Of thefe globules but 
two were fit for ufe, when they came into my 
hands, viz. that which, according to Father de la 
Torre, magnifies the diameter of the objedl 640 
times, and that which magnifies 1280 times. The 
lenfes of the greatcfi magnifying power made in 
London are thofe of T ‘-_th of an inch focus, which,, 
even allowing eight inches to be the focal difiance of 
the naked eye, magnifies the diameter of the objedt 
only 400 times ; a power much inferior to what 
may be obtained by globules, and particularly by 
that globule, which according to Father de la Torre 
magnifies the diameter 1280 times; and this globule 
I have ufed in fome of thefe experiments. But our 
lenfes, though inferior in magnifying power to thefe 
globules, are much fuperior in diiiindlnefs ; the 
