Trigonometrical Survey. 633 



in the forenoon of the same day, (97 4' 14") 



is 94°i6'43" 



Hence, 94 16' 44" may be considered as the true angle be- 

 tween the meridian and the staff on Hemmerdon Ball. 



The angle between the station on Rippin Tor and Hemmer- 

 don Ball, is 121 17' 7", 75 ; therefore, 121 17' 7^,75 — 94 16' 

 44" = 2 7 o' 23",75, is the bearing of Rippin Tor, north-east of 

 Butterton. This angle, with 62951 feet, gives 28585,2 feet, and 

 56086,6 feet, for the distance of Rippin Tor from the meridian 

 and perpendicular ; which, using 61182 and 60847 fathoms, for 

 the lengths of degrees on the meridian and perpendicular, re- 

 spectively become 4' 4o /, ,g, and 9' 13". Therefore, in the right 

 angled spherical triangle BPT, (Plate XXX, Fig. 2,) in which B 

 is Butterton, P the pole, T Rippin Tor, and R the point where 

 the parallel to the perpendicular cuts the meridian, we have the 

 co-latitude of T, or Rippin Tor, = 39 26' o",9, and RT = 4' 

 4o",3, We have, consequently, cosine 4' 40^,3 : radius : : cosine 

 39 26' o,"9 : cosine 39 26' o,"7, the co-latitude of the point 

 R. So PB = PR + RT = 39 26' o", 7 + 9' 13" = 39° 35 ' 

 13", 7 ; therefore, the latitude of Butterton is 50 24' 46",3, and 

 its longitude west from Greenwich, 3 52' 47" 5. 



Art. xx. Calculation of the Distance between Hensbarrozv and 



Butterton. 



The most convenient, as well as the most accurate means of 

 computing this distance, will be by referring to the Lvith, Lvnth, 

 and Lxivth triangles, in the series of 1796, where the sum of the 

 observed angles at Carraton Hill is 136 52' 43". The correc- 

 tion for reducing this angle to that formed by the chords, is 4" ; 

 therefore, 136 52' 39" is the proper angle for computation. 



