434 dn Account of the Measurement 
From the last triangle, we get 117457,1 for the distance 
between Corley and Arbury Hill. By the xi. triangle, the dis- 
tance between those stations is 11 7463 feet; there is, therefore, 
a difference of nearly six feet between the two determinations ; 
a quantity which cannot be considered unexpectedly great, as 
the side is more than twenty-two miles in length, and the whole 
series nearly two hundred miles long. If the computation had 
been carried on from Dunnose all the way up, the bases on 
Hounslow Heath and Salisbury Plain would have given the 
length of that on Misterton Carr about one foot greater than its 
measured extent. If the sides of the triangles contiguous to 
Corley and Arbury Hill be recomputed, from the mean distance 
between those stations, viz. 117460 feet, no doubt whatever can 
be justly entertained of the general accuracy of the whole. These 
mean distances, as I have before observed, will be used in the 
calculations of the total length of the meridional arc. From the 
Base in the north, I have numbered the triangles downwards : 
the reason is obvious. 
Calculation of the meridional Distance between Dunnose and 
Clifton. 
To do this, it will be right to compare the distances of the 
several stations from the respective perpendiculars, both of 
Dunnose and Clifton, as derived from the observed direction of 
each meridian. 
In the Phil. Trans, for 1795 it will be seen, that the direction 
of the meridian was observed at the station on Dunnose, in 1793, 
the staff to which the pole star was referred being placed on 
Brading Down. The angle between that staff and the meridian, 
(see page 517 of that volume,) was found to be 2 1° 14' 1 i",5, as 
