49 2 Mr . hutton 0# Converging Series , See. 
By a pretty exadt eftimate, which I have made, of the 
proportion of the trouble or time in computing the cir- 
cumference by this middle form of the value of a, and 
by Mr. machin’s theorem, I have found, that the com- 
putation by his method requires about |th or — th more 
time than by mine. And its advantage over any of the 
feries’ invented by euler or others, is ftill much more 
considerable. 
XXIX. An 
