xxii 
INTRODUCTION. 
plaufible this theory may -feem, at firft light, experience 
has abundantly detected its fallacy. In confequence of 
Captain 
ame time, as well as both before and fince. And, by comparing thefe obfervations toge¬ 
ther, he concludes, that at the time when Captain Cook was in thele feas, the variation 
of the needle at Cape Circumcifion muft have been io° Wefterly : whereas, in the moft 
Wefterly point of Captain Cook’s .track, where he was fufficiently near the parallel of 
54° South, to have feen land fituated in It, the variation was 13 0 £ Wefterly. This dif¬ 
ference of 3 0 £, in the variation, anfwers to about 7 0 of longitude, in this part of the pa¬ 
rallel of 54 0 South : and by fo much did Captain Cook fall in with this parallel to the 
Eaftward of what he ought to have done to fee the land in queftion. “ Hence (M. Le 
“ Monier infers), that it is not furprizing the Britifh navigator fhould not find Cape 
“ Circumcifion under a meridian which is 28° £ to the Eaftward of Ferro, when it is 
“ really fituated under a meridian which is but 21 0 £ to the Eaftward of it.” 
In replying to thefe allegations, I lhall, firft, fhew, that, granting the dependence which 
M. Le Monier fuppofes may be placed on obfervations of the variation made at fea, he 
lias ftated the quantity of the variation, obferved on board the Refolution, very erro- 
neoufly. 
Secondly, I fhall prove, beyond contradiction, that obfervations of the variation, made 
at fea, cannot be depended on, for the purpofes to which M. Le Monier has applied 
them. 
And, laftly, that no material error had crept into M Bouvet’s reckoning; but that if 
any error did exift, it muft have been of a contrary nature to that which M. Le Monier 
fuppofes. 
That M. Le Monier has not given altogether a true reprefentation of the matter, will 
appear from hence. On the 16th of February, at noon *, the Refolution was in latitude 
54 0 3if' South, which is fufficiently near the parallel of 54 0 South, to fee high land, the 
Northern extremity of which lies to the Southward of that parallel; and at that time we 
were in 6° Eaft of Greenwich, or 23 0 £ Eaft of the ifiand of Ferro : that is, 4 0 f lefs 
than is affigned for our fituation by M. Le Monier. On the evening of the fame day, 
the ftiip being in latitude 54 0 24'', and longitude 6° 30'', or 24 0 \ Eaft of Ferro, the 
variation was no more than 12 0 7 / Weft, which alfo is near a degree and half lefs than 
M. Le Monier fays it was, when we firft arrived in a proper parallel for feeing Cape 
Circumcifion. It is true, the next morning, in latitude 54 0 2i£ / South, longitude 
8° 6 ' Eaft, 
* I here go by the dates in <f The Original Aftronomical Obfervations,” printed by or¬ 
der of the Board of Longitude; which, after the 14th of February 1775, differ one day 
from Captain Cook’s dates. 
