244 PHILOSOPHICAL TRANSACTIONS. [ANNO 1/97. 



that the nearest part of the Scilly Isles is about 24.7 miles from the Land's End, and 

 the farthest nearly 34. 



This account of the trigonometrical survey then relates to that carried on in Kent, 

 in the years 1795 and 1796, with the small circular instrument. The instrument 

 used in this survey was announced in the Philos. Trans, for 1 795. It was made by 

 Mr. Ramsden ; and was about half the size of his large theodolite, or circular in- 

 strument, with which were taken the horizontal angles, but nearly similar to it in 

 all its parts. This instrument, on account of its portable size, may very readily be 

 taken to the tops of steeples, towers, &c. and is therefore extremely well adapted to 

 the uses for which it was intended. Then follows a list of the situations of the 

 stations on which observations were made with the small circular instrument, in 

 the summer of the year ] 7Q5 ; with the triangles for determining the distances of 

 the stations. As the station on the Keep of Dover Castle, in 1 787, was directly 

 over the steps of the Turret, a new point was chosen about 6^ feet from the former, 

 where the instrument could stand conveniently : this new point is about 2.8 feet 

 farther from Folkstone Turnpike, and 1 foot farther from Paddlesworth, than the 

 point marking the old station. From General Roy's account of the trigonometrical 

 survey in 1787, we have 



Dover Castle from Folkstone Turnpike 31554.6 > f 



from Paddlesworth 42561.2 J 



Now, augmenting those distances in the proportion of 141 747 to 141753 (see 

 Phil. Trans, vol. 80, p. 595, and the vol. for 1795, P- 508), we get 31556, and 

 42563 feet; to which adding 2.8, and 1, respectively, we have 



The new point on Dover Castle from Folkstone Turnpike 31558.8 ") f 



from Paddlesworth 42564 J 



In order to obtain the distance between Waldershare and Dover Castle from 

 those new sides, or distances, the three angles of the following triangle were very 

 carefully taken. 



f Dover Castle 3° 49' 16" 3° 49' 15" ) 



1 1 Folkstone Turnpike 36 6 31 36 6 30 > for computation. 



I Hawkinge 140 4 16 140 4 15 J 



The 3d angles of the next 2 triangles were not observed : 



Hawkinge 44° 23' 30" 



Dover Castle 73 53 44 



Waldershare 6l 42 46 



Dover Castle 62 24 7 



Paddlesworth (the station of 1787) 32 36 9 



Waldershare 84 59 44 



Feet. 



By the first 2 triangles, Dover Castle from Waldershare 23019 4 1 5 mean distanCGt 



From the latter 23021.5 J 



* , u , • r, f Dover Castle 28976. 



And Hawkinge from.- { Waldershare 3l6l6. 



Finally are deduced the distances of the objects intersected in the survey with the 

 small circular instrument, from the meridian of Greenwich, and from the perpen- 

 dicular to that meridian. Also their latitudes and longitudes. At Folkstone turn- 

 pike, the bearing of the station on Dover Castle in 1787, from the parallel to the 



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