43° An Account of the Measurement 
No. of 
triangles. 
Names of stations. 
Observed 
angles. 
Diff. 
Spheri- 
cal 
excess. 
Error. 
Angles corrected 
for calculation. 
Distances. 
X. 
Brill 
Epwell 
Arbury Hill 
- 
3 + 23 58*5 
85 0 18,5 
60 35 45,5 
—0,65 
— 1,10 
—0,70 
u 
" 
34 *3 57.5 
85 0 17,5 
60 35 45 
Feet. 
180 0 22,5 
2,46 
+ 0,04 
Arbury Hill from | f^ 11 
- 
- - 
83098,4 
i 4 6 53 ° 
XI. 
Arbury Hill 
Epwell 
Corley 
- 
89 57 4,5 
54 45 i 8.75 
35 1 7 36>75 
-1,14 
— °>57 
- 0.57 
89 57 5.5 
54 45 18,25 
35 17 36,25 
180 0 0 
2,29 
-2,29 
Corley from 
/ Arbury Hill 
\ Epwell 
. 
‘ 17463 
143827,8 
By the last triangle, the distance from Corley to Arbury 
Hill is 117463 feet, which distance, and all the others consti- 
tuting the sides of this part of the series, are deduced from the 
base on Hounslow Heath, as well as that on Salisbury Plain. 
With regard to the triangles connecting the stations at Corley 
and Arbury Hill with the base recently measured in the north, 
it will be proper to let them rest partly on that base, and partly 
on the side Corley and Arbury Hill. And here I would remark, 
that in carrying on a series of triangles, whether for the purpose 
of a meridional measurement or otherwise, it is proper that a 
base of verification, answering at the same time as a new one 
of departure, should be measured every hundred miles at least. 
With this idea, therefore, the foregoing triangles, as well as those 
composing the remaining part of the series, should be furnished 
with three base lines, viz. one at each extremity, and the other 
in the middle. In calculating the sides, were the series thus 
