34>3 
Measurement of three Degrees of the Meridian . 
and 7883 ,/ > 493, or 2° n' 23", (> and 23", 49, as the calculated 
extent of the arc. But the arc observed was 2 0 1 i' 19", 83, 
according to M. Delambre, and 2 0 1 1/ 20", 85 according to 
M. Mechain ; so that the least difference between the cal- 
culation and the observations will be 2", 64. M. Delambre 
is of opinion, that the latitude of Dunkirk, which is sup- 
posed to be 51 0 2' 9", 20, should be diminished ; and in fact 
the distance between the parallels of Dunkirk and Green- 
wich, which is 25241,9 toises, gives by the mean of the three 
assumed ellipticities 2 6' 32 ",3 for the difference of latitude. 
After deducting this quantity from 51 0 28' 40", the supposed 
latitude of Greenwich, there remains 51 0 2' 7", 7 or 8", for 
that of the tower at Dunkirk. If from this again we deduct 
the calculated arc 2 0 11' 23", 5, we have 48° 50' 44", 5 for the 
latitude of the Pantheon, while, according to the observations 
of M. Delambre, it is 49'', 37, or 48", 35 by those of M. Me- 
chain. If various circumstances, with regard to unfavourable 
weather, and also others of a different kind connected with 
the revolution, and of which M. Delambre complains with 
much reason, have occasioned some uncertainty with respect 
to the observations at Dunkirk, still the numerous observa- 
tions made at Paris, both by him and by M. Mechain at a 
more favourable season, and in times of perfect tranquillity, 
render the supposition of an error of 4 seconds in the latitude 
of the Pantheon wholly inadmissible. It is, however, too true, 
that such errors are possible, and it is only by careful perse- 
verance, and by repeated verification, that they are to be dis- 
covered and removed, as we have seen to be highly probable 
with respect to the station at Arbury Hill. 
But the same celebrated observer, M. Mechain, who handled 
