512 The Account of a 
Now it is evident, that if all the angles of the four triangles 
contained in the quadrilateral formed by the stations on Dun- 
nose, Rook's Hill, Chanctonbury Ring, and Beachy Head, 
were accurately corrected for computation, the distance from 
Beachy Head to Dunnose would be found the same from each 
triangle, by making use of the side Rook's Hill and Chancton- 
bury Ring (which is common to the two most oblique ones): 
therefore, having assumed that distance, we found by compu- 
tation, that if each of the above errors is supposed to be in one 
angle only of the respective triangles, these angles must be the 
three observed ones, namely, 28° 2 9' 30"; 27 0 o' 13"; and 
122 0 59' 14,", 5; these are augmented accordingly, before the 
angles are finally corrected for computation. The angles of 
the 39th triangle, resulting from those of the other triangles, 
are 
Chanctonbury Ring - 157 0 59' 5i",25 
Rook's Hill - - 14, 17 32,75 
Beachy Head - 7 42 37,25 
before they are reduced to the angles formed by the chords. 
