some observations made with chronometers. 365 
well among themselves, still they prove that the result of 
the Survey is about 3" too small ; or that it is nearly in the 
same proportion too small, in which the difference of longi- 
tude between Dover and Falmouth, and likewise by the ob- 
servations of the year 1822, that between Greenwich and 
Falmouth were found to be deficient. We may therefore 
safely infer, that it is a general and proportionate defect of 
all longitudes deduced from the Survey, and not the erroneous 
longitude of any particular station, which has caused the dis- 
agreement between the results of the chronometers and of 
the Survey. Supposing the final result above found to be 
correct, the increase of the longitude of the Survey =25* 23 ".5, 
is 4". 92, and at this rate all the longitudes contained in the 
Account of the Survey must therefore be increased. Apply- 
ing this correction, we shall have, 
the longitude of Dover (at the Station of the Survey) . . o h 5' i7",52 E 
Portsmouth (at the Station of the Observatory) . 4 24 .75 W 
Pendennis Castle (at the Station of the Flag Staff) 20 io .8 1 
In the year 1822 I found the latter, by going from Greenwich to 
Falmouth . 20 1 1 .49 
and by returning from Falmouth to Greenwich . . . . 20 11 13 
The difference of longitude between Falmouth and Madeira 
was found, by the mean of the results of seventeen chrono- 
meters, to be o h 47' 2 8".2i. The extremes of these results 
differ indeed 20", but as 9 of them, the mean of which is 
o h 47' 28".23, do not differ more than 3". 71 from one another, 
it is to be presumed, that the above given result is not far 
from the truth. The station at Madeira (the garden of the 
British Consul in the town of Funchal) is therefore in longi- 
tude i h / 39".o2 W of Greenwich. 
I 
