7 1 8 Mr. mutton’s Calculations to afcertain 
racy. I fhall for this purpofe feledl the third fe&ion as 
not containing fo many poles as fome of the others. This 
fe£tion commences at s, and is car- 
ried up the hill in a vertical plane, 
making an angle of 105° with the 
line rs. The direction of this 
plane is here reprefented by the 
line s ppp making with rs the an- 
gle rs/>= 1 0 5 °. The points ppp 8cc. 
mark the places of the poles, whofe angles of elevation 
or depreffion were taken at s with a proper inftrument, 
and they are written in the fecond column of the table in 
this example. At r were obferved the feveral horizontal 
angles, which lines fuppofed to be drawn from thence 
made with rs, and thefe are placed in the third column. 
And fince in every triangle rs p, the angle s is conftant, 
and the fum of r and p is equal to the conftant quantity 
75 0 : therefore each of the angles' r, or the numbers in 
the third column, being lubtradted from 75 0 , there re- 
mains the correfponding angle p : and thefe remainders 
are placed in the fourth column. Then, fince the me- 
thod of folution is this, as f .p : f.R : : rs : s p — i-^x RS ; and 
again, as radius (1) : tang. elev. : : s p: alt. of p above s = 
(* R 
spx tang. elev. = x rs x tang. elev. Or in logarithms 
A f.R 
From — 180® 
Take z. s — 105 
Leaves z. R -f Z. p ~ 75 
