Mr. jeaurat’s Account 'of, kc. 
Focal dif- 
tance of the 
lens A and 
the equiva- 
lent AD. 
Focal diftancesof 
die lenfes a and 
c, and diftance 
c a from the id 
tens c to the 
third a. 
Diftanee ac from 
the. firtt lens -a to 
the fecond c. 
Diftance a\ from 
the firft lens a to 
third a. 
Whole diftance 
a d. 
Diftance cd from 
die ad lens c to 
the focus d. 
Fr. ft. 
In. 
Fr.ft. In- 
Lin. 
Fr.ft. In. 
Lin. 
Fr.ft. 
In. 
Lin. 
F r. ft. 
In. 
Lin. 
Fr. ft. 
In. 
Lin. 
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