SURVEYING OPERATIONS. 323 
of which had before been laid down; and occa¬ 
sionally the same results were obtained, by ob¬ 
serving the bearing, and measuring the angle sub¬ 
tended by any cliff or mountain whose elevation 
had previously been ascertained. 
In many of these investigations and operations, 
I laboured under great disadvantages, as not only 
all calculations, but also all observations, of every 
description, devolved upon myself, not having a 
person among my ship’s company who could be 
depended upon to take a bearing or an angle; 
nor even a set of altitudes, either for determining 
the longitude by the chronometer, or the varia¬ 
tion, by the sun’s azimuth. Hence in finding 
the variation, I had first to take the altitude of 
the sun, and mark the time by my watch, and 
then to ascend the mast, and take the azimuth 
from the crow’s-nest. This process necessarily 
involved me in a troublesome calculation to as¬ 
certain the change of azimuth for the elapsed in- 
terval. When the interval, however, happened 
to be very short, an allowance of a degree of azi¬ 
muth for every four minutes of elapsed time, was 
sufficiently accurate ; but, in most cases it was 
necessary to resort to calculation for this correc¬ 
tion. In observations for the longitude, by chro¬ 
nometer, I observed the time, took the altitudes, 
and noted them down ; and, in lunar observations, 
X 2 
