some observations made with chronometers. 371 
observation, -d—. The length of the geodetical line BD, 
supposing the difference of longitude as determined in the 
account of the Survey, viz. i° 26' 47".9S, would be 338231 
feet ; whereas it was found to be 339397.6 feet ; but if the 
longitude be increased in the ratio determined by the chro- 
nometers, the line will be 339334 feet, which is only 63.6 
feet short of the measurement. The spheroid resulting from 
the compression which would make the difference of longi- 
tude of B and D == i° 27' 4". 75 (as it ought to be according 
to the results of the chronometers ) , and from the degree of 
the meridian in latitude 50° 41', viz. 60851 fathoms, would 
have these dimensions: radius of the Equator = 3487907 
fathoms ; semi-axis = 3476687 fathoms; compression 
The results of the chronometrical observations are therefore 
as much as could be expected in accordance with the correct 
determinations of the figure of the earth. 
I am, Sir, 
your most humble and obedient Servant, 
J. L. Tiarks. 
To Dr. Young, 
Secretary of the Board of Longitude. 
