[ +ae3 3] 
annual change, which might make a difference of a year or two 
in the computation (as is the cafe with refpe@t to Mr. Gibfon). 
Without the ftridteft regard to the dates, as well as the precife 
quantity of the annual difference, fhort intervals of time to 
eftimate by are very uncertain.—The intermediate dates, however, 
are next to be compared. 
1. From 1751 take 1745, the remainder is fix years; and from 
19 degrees take 18 degrees, the remainder, reduced to minutes and 
divided by fix, quotes only 10 minutes. [In this inftance, the 
interval being fmall, and the variation in all likelihood not very 
accurate, the quotient muft be ambiguous, as before remarked ; 
but if what I have to fay hereafter be admitted, the increafe of 
the variation, even in this fhort interval, will come up to my 
expectation. | 
2. From 1772 take 1751, the remainder is 21 years; and from 
23 degrees 30 minutes take 19 degrees, the remainder, reduced 
to minutes and divided by 21, quotes 12 minutes 51 feconds.— 
[By thefe two it is evident Mr. Gibfon might have fuppofed the 
variation for feveral years the fame, or, at leaft, imagined that two 
or three years would make no fenfible alteration ; but one year, 
in this inftance, makes a difference in the calculation of 35 
feconds. | 
3. From 1786 take 1772, the remainder is 14 years ; and from 
26 degrees 21 minutes take 23 degrees 30 minutes, the remainder, 
reduced to minutes and divided by 14, quotes 12 minutes 13 
feconds nearly, 
Voi. IV, QO G3 4. Lastiy, 
