INTRODUCTION. xxiii 



fallacy. In confequence of Captain Cook's voyage, now 

 under confideration, we have a thorough knowledge of the 



ftate 



more to the Eaftward, and after we had run 3° 4 on the parallel we were then on, the 

 variation was no more than 13° 16' Weft. It .is alfo worthy of remark, that on the 

 14th, in the evening, latitude 56'^ 141' South, and longitude 4° 50' Eaft, which is 

 but 1° 10' to the Weft ward of the point, where the Refolution came firft into a 

 proper fituation to fee land, fituated in the parallel of 54° South, the variation obferved 

 was no more thnn 6° 50' Weft. And we may further add, that on the ift of March, 

 1774, the Adventure had no more than 12° J Weft variation, though fhe was then 

 confiderably both to the Northward and Eaftward of our fituation on the 17th of Fe- 

 bruary in the morning, on both which accounts the variation ought to have been 

 greater, inflead of a whole degree lefs. From all thefe circumftances, there can be 

 little doubt but that the two variations, obferved by us on the i6th and 17th of Fe- 

 bruary, 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 1 1° | Weft, inftead of • 

 1 3°!, as M. Le Monicr 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° South, when flie crofted the meridian 

 which is 21° f to the Eaftward ofFerro; that is, 3°! Eaft of Greenwich^ the long!- • 

 tude which M. Le Monier zffigns for Cape Circumcifion, to fee if it had been in that 

 fituation ; yet her confort, the Adventure, was for feveral degrees on each fide of thur. 

 meridian ; and efpecially when {he had 10" | of Weft variation, full as near to the pa- 

 rallel of 54° South, as JH. Bouvet v/SiS to the land when he faw it * : and on the day 

 that fhe aflually pafled that meridian, had fine clear weather f. Hence, therefore, 

 granting J14. Le Monier his own argumentSj 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 finding the longicude, it 12 utterly impoJIible that 

 both the Refolution and Adventure could have palled Cape Circumcifion without 

 feeing it. But I fliall now fhew, that thefe obfervations are liable to a much greater . 

 error than the whole quantity, fo vigoroufly infifted on by this gentleman. 



I will not h're run the rifle of incurring M. Le Monier''s difpleafure, by calling the 

 accuracy of M. Biuvet\ obfeivations in queftion ; but will admit every thing that he 

 hi mfelf can think due to the inftruments and obfervations of that deferving navigaior. 

 It is enough for my argument, and it is but too evident, from the obfervations them- • 

 felves, that ours were by no means capable of determining the variation to fo fmsll a 



quantitv 



* See The Original Aflronomical Obfervations, p. 1851 and Bouvet's Voyage, publifhed 

 by Mr. Dalrymple, p. 4, and 11. 



■\ See the Obfervations, p. 25S. 



