Trigonometrical Survey. 595 



the angles themselves, might afford a closer agreement ; but I can 

 see no just reason for making any alterations in one or the other. 

 I shall now take the means of the distances, as derived from both 

 bases, and consider 68652,2 feet as the true distance from Ash 

 Beacon to Bradley Knoll ; and 61962,3 feet for that between Bradley 

 Knoll and the station on Mendip Hills. 



In one of the foregoing triangles, (Bull Barrow, Bradley Knoll, 

 and Ash Beacon,) the distance between Ash Beacon and Bull Barrow 

 is found to be 75451 feet. If the mean distance between Bradley 

 Knoll and Ash Beacon, viz. 6ig62,,g feet, be now used, 75452,7 

 feet becomes the distance between those stations ; arid this I shall 

 use, in computing the sides of the two triangles which immediately 

 follow. 



No. of 

 triangles 



XXI. 



Names of stations. 



Ash Beacon 

 Bull Barrow 

 Mintern 



XXII. 



Pilsden 

 Ash Beacon 

 Mintern 



Observed 

 angles. 



34 18 56,25 

 51 26 42 



94 »4 2 3 



180 



Diff. 



— 0,14 



— 0,13 



— 0,32 



Spheri 

 cal 



1,25 



Mintern from -j 



°>59 



Error. 



+ 0,66 



Angles corrected 

 for calculation. 



34 is 55-75 

 51 26 41,75 



94 14 2 2>5 



Ash Beacon 

 Bull Barrow 



35 3 l 

 49 ZI 3 8 > 2 5 

 95 35 22 



180 



1,25 



-0,24 

 -0,24 

 -0,60 



1,08 14-0,17 



35 3 0,75 

 49 21 38 

 95 35 21.25 



Pilsden fr„ m { ^Beacon 



Distances. 



Feet. 



59166,6 



42653,7 



I02 535 

 78177,6 



In our last account, (see Phil. Trans. 1797. p. 455 and 456.) the distance from Bull Barrow 

 to Mintern was found to be 42653,4 feet; and the distance from Piisden to Mintern 78177 

 feet. The distances derived from the above triangles are very nearly the same ; a difference 

 of a few inches only existing between them. 



