47 8 Mr. wales on the Refolution , See. 
unexhibited in numbers, for want of fome fuch eafy method 
as this, or have done it by means of a long andlaborious 
feries of difficult computations ; which, beiide the labour 
attending them, are always fubjedt to a variety of errors, 
which cannot be detected, in many cafes, without repeating 
die operation* 
f 
