INTRODUCTION. 
xxiii 
Captain Cook’s voyage, now under confederation, we have 
a thorough knowledge of the Rate of the Southern hemi- 
fphere, 
8° 6 / Eaft, we had 13 0 42' Weft variation; but this was after we had run more than 
two degrees within fight of the parallel of 54 0 South. It is, moreover, highly pro¬ 
bable, that both thefe variations were too great; for, on the 17th, in the evening, lati¬ 
tude 54 0 25' South, and longitude 9 0 2 o' Eaft 5 that is, i°| more to the Eaft ward, and 
after we had run 3°^ on the parallel we were then on, the variation was no more than 
13 0 1 6 / Weft v It is alfo worthy of remark, that on the 14th, in the evening, latitude 
56° 14!' South, and longitude 4 0 50' Eaft, which is but i° io' to the Weftward of tire 
point, where the Refolution came firft into a proper fituation to fee land, fituated in the 
parallel of 54 0 South, the variation obferved was no more than 6° 50' Weft. And we 
may further add, that on the ift of March, 1774, the Adventure had no more than 12° -f- 
Weft variation, though fhe was then confiderably both to the Northward and Eaftward 
of our fituation on the 17th of February in the morning, on both which accounts the va¬ 
riation ought to have been greater, inftead of a whole degree lefs. From all thefe cir- 
cumftances, there can be little doubt but that the two variations, obferved by us on the 
16th and 17th of February, were too great; or that the variation, at the point where the 
Refolution firft came fufficiently near the parallel of 54° South, to fee land, the Northern 
extremity of which is fituated in that parallel, could not be more than 11° \ Weft, inftead 
of 1 3 ° h as M. Le Monier has reprefented it. 
Under this head of enquiry I may alfo obferve, that although the Refolution was too 
much to the Southward of the parallel of 54 0 South, when fhe crofted the meridian which 
is 21 0 1 to the Eaftward of Ferro; that is, 3 0 § Eaft of Greenwich, the longitude which 
M. Le Monier afiigns for Cape Circumcifion, to fee it, if it had been in that fituation; yet, 
her confort, the Adventure, was for feveral degrees on each fide of that meridian; and 
efpecially when fhe had io°£ of Weft variation, full as near to the parallel of 54 0 South, 
as M. Bouvet was to the land when he faw it * : and on the day that fhe actually pafted 
that meridian, had fine clear weather f. Hence, therefore, granting M. Le Monier his 
own arguments, which, however, I have proved to be erroneous ; and that obfervations 
made at fea, for the variation of the compafs, may be depended on for the purpofe of find¬ 
ing the longitude, it is utterly impoftible that both the Refolution and r Adventure could 
have pafted Cape Circumcifion without feeing it. But I fhall now fhew, that thefe ob¬ 
fervations are liable to a much greater error than the whole quantity, fo rigoroufly infifted 
on by this gentleman. 
I will 
* See The Original Agronomical Obfervations, p, 185, and Bouvet’s Voyage, publilhed 
by Mr. Dalrymple, p. 4, and 11. 
f See the Obfervations, p. 218. 
