26 INTRODUCTION TO THE 



sufficient space for the corresponding mass of land, 



equal, or a greater error ? which, without any reasonable cause 

 for offence, we might suppose they were. 



It is not necessary to account for these differences in the ob- 

 served variations in this place, nor yet to point out the reasons 

 why such anomalies have not been noticed in observations of this 

 kind before. I shall, however, remark, that I have hinted at some 

 of the causes in my introduction to the observations which were 

 made in Captain Cook's second voyage; and many others will 

 readily offer themselves to persons who have had much practice in 

 making these observations, and who have attentively considered 

 the principles on which the instruments are constructed, and the 

 manner in which they are fabricated. Nor is it at all surprising, 

 that the errors to which the instruments and observations of this 

 kind are liable, should not have been discovered before, since no 

 navigators before us ever gave the same opportunity, by mul- 

 tiplying their observations, and making them under such a variety 

 of circumstances as we did. 



Having now fully shown, that the circumstances, brought for- 

 ward by M. Le Monier> in support of his argument, are neither 

 such as can be depended on, nor yet fairly represented, I shall 

 next attempt to demonstrate, that it is utterly improbable M.Bouvet 

 could be out, in his account of longitude, so much as is here sup- 

 posed, in the short run which had been made from the island of 

 St. Catherine, the place they took their departure from : on the 

 contrary, that there is sufficient reason to believe the error, of 

 whatever magnitude it might be, was of a different nature from 

 that contended for, and that the two ships, instead of being to the 

 westward of their account of longitude, were actually to the 

 eastward of it. For according to their journals, extracted from 

 the archives of the French East-India Company, by M. D'Apres, 

 printed under his inspection, and published by Mr. Dalrymple, 

 F. R'. S. amongst other voyages made for the purpose of examin- 

 ing the southern parts of the Atlantic Ocean, the longitude, ac- 

 cording to the Eagle's run from St. Catherine's, was, 26 27', and 

 according to the Mary's, 26 20' east of Teneriff ; that is, 9 57', 

 and 9 50' east of Greenwich, or 27 43', and 27 36' east of 

 Ferro. But the Mary, which went to the Cape of Good Hope, 

 made 7 13' east longitude from the land in question, to that 

 place. Consequently the Cape of Good Hope being in longitude 

 18 23' east of Greenwich, Cape Circumcision will be in 11 10' 

 east of Greenwich, or 1 20' more to the eastward than the run 

 by the same ship from the island of St. Catherine's makes it. 

 Again the Eagle made the difference of longitude between Cape 

 Circumcision and the island of Rodrigues 49 44' ; and by the 

 observations of M. Pingre, this island is in 62 50' of east lon- 

 gitude from Greenwich : Cape Circumcision is therefore in 13 6' 

 east of Greenwich, or 2 9' more to the eastward than by the 



