Trigonometrical Survey. 677 



Shooters Hill, and the one newly chosen ; this angle subtended 



94° 19' °">5- 



The distance from Severndroog Tower to the old station at 

 Wrotham, is 79960 feet. But, it must be observed, this dis- 

 tance is not precisely the same as that given by General Roy, 

 because an allowance is made for the error in the reduction of 

 the bases, in the surveys of 1787 and 1788. 



With the distances 79960 feet and 205,5 feet, and the included 



angle, 94 19' o",5, we find the distance of the Flag-staff on 



Severndroog Tower, from the new station = 79944 feet; with 



this distance, a part of the following triangles have their sides 



computed. 



Art. xxxviii. Principal Triangles. 



Names of stations. 



Observed angles. 



Distances of the stations. 



Wrotham 

 Gravesend 

 Severndroog Tower 



1 11 

 62 54 38 



82 39 21 



> Gravesend - < 



Feet. 

 45578 



71/62 



Gravesend 



Langdon Hill - - 



Severndroog Tower 



95 53 59 



53 47 25 



iLangdon Hill - < 



44886 



88470 



Gravesend 

 Hadleigh Steeple 

 Langdon Hill 



34 3i 53 

 43 ii 5 1 



I Hadleigh Steeple - I 



64076 

 37I7I 



Gravesend 



Hadleigh 



Halstow » 



30 24 19 — 21 



41 46 32—33 



107 49 5— 6 



JHalstow Steeple - 1 44 ^9 





179 59 57 



1 



Gravesend 

 Halstow - 

 Gadsbill 



31 38 21 

 24 18 21 



JGadshill - - | 



222/7 

 28390 



Halstow - 

 Hadleigh Steeple 

 Sheppey Isle 



59 18 6 —5 



49 J 3 33i— 32 

 31 28 24 —23 



>Sheppey - I 



49409 

 64387 





180 3 ,5 





MDCCC. 



4S 



