638 The Account of a 



making it 60851, in order to get the length of the degree in 

 50 41'; (see Phil. Trans. 1795, p. 537;) these 9 fathoms, 

 however, were not arbitrarily assumed, but computed. If the 

 latitude of Paris be 48 50' 15", [Conn, des Terns, 1797-98, 

 p. 373,) the length of the degree will be about 7 fathoms 

 greater, which will make the degree in 50 41', 60849 instead 

 of 60842 fathoms. 



The latitude of the station on Beachy Head, 50 44' 23", 7, 

 was found by using 60861 fathoms for the length of a degree 

 on the meridian in 51 6'; but, if it be true that 48 50' 15" is 

 the latitude of Paris, the latitude of Beachy Head will be about 

 one-third of a second greater. This seems to be the limit of the 

 probable error in the computed latitude of this station ; since its 

 proximity to the meridian of Greenwich, obviates any doubt of 

 the conclusions being affected by any uncertainty respecting the 

 length of the degree of the great circle perpendicular to the 

 meridian. 



The latitude of Dunnose was determined by computing the 

 distance between the parallels of that station and Beachy Head ; 

 (see Phil. Trans, for 1795, p. 522 ; ) which method is very exact, 

 and preferable to any other, since the small space between the 

 parallels was determined with great accuracy, leaving not a 

 doubt of a greater error than 3 feet, a quantity corresponding 

 to about ~d part of a second. And, since the same method 

 has been adopted to find the difference of latitude between 

 Black Down and Dunnose, it is highly probable that the lati- 

 tude of the former station is not removed more than ^ths of a 

 second from the true one, that of Beachy Head being supposed 



= 50° 44' 23">7- 



