140
Remarks on the use of
[July
a function the error is given of the difference of longitude, by changing the formula.
In the diagram (Pl. 4 fig. 3) let A D be the meridian of the first station, B C the perpendicular of any other station, then A being the pole, D C will be the parallel of latitude of C, and A D will be the co-latitude of E, and not A B, and B D will be the error or the difference of latitude between the foot of perpendicular and the parallel.
and the being nearly , and substituting the value of
and taking and for the sines
which is the formula before given,—but the angle B A C is the difference of longitude between B and C, and in the right angled triangle A B C
substituting this in the last formula
or become
from this formula the following table is computed x always subtractive:—