[ 3©o ] 
fathom in the approximate height j and if you have 
chiliads of fathom in your approximate height, find 
the corredlion for them, by taking the decuple of the 
corredtion for the correfponding centuries. Add 
thefe feveral parts of the correction together, and 
call the fum N. 
7. In the little table look, either a- top or in the 
outer vertical row to the left, for the units of de- 
grees in the temperature of the air, over and above 
decades, and colledt the corredtion for thefe, for the 
units, decades, centuries, &c. of fathom in the ap- 
proximate height, by taking the numbers found in 
the little table, and proper multiples thereof. Add. 
thefe numbers together, and call the fum n. 
8. If the fign of the correction found in the great 
table be add t0 the approximate height ; 
but if the fign of the corredtion found in the great 
table be — , fubtradt N — n from the approximate 
height. The fum in the former cafe, the remainder 
in the latter, is the corredt height, according to- 
M* pe luc’s rules. 
EXAMPLE. 
