VOL. XXIX.] PHILOSOPHICAL TBANSACTIONS. 113 



Cabo Dello, at the mouth of the river, and which is about 3 leagues more 

 northerly than the town, I found the latitude not less than 6° 55' south, and 

 consequently that of the town more than 7 degrees. 



The other is in a discourse of M. de Lisle, in the Memoirs of 1 7 10; where 

 he compares the variations observed in some late voyages, with my map of the 

 variations. Among other things, it is there said, that on the east side of the 

 island St. Thomas, under the equinoctial line, M. Bigot de la Cante, second 

 lieutenant of the king's ship la Sphere, had, in the beginning of the year J 708, 

 found the variation 1 l-i-°, whereas my chart makes it only 54-°. It is true, that 

 I never observed myself in those parts ; and it is from the accounts of others, 

 and the analogy of the whole, that in such cases I was obliged to supply what 

 was wanting ; and possibly there may be more variation on that coast than I 

 have allowed. But consulting my chart, which was fitted to the year 1700, I 

 find I then make the variation at the isle of St. Thomas full 7-^" and not 5^°, 

 which, by the year 1708, might well rise to near 9°. So that the difference 

 will become very tolerable ; whereas an error of 6 degrees, such as is here re- 

 presented, would render the credit of my chart justly suspected, and so useless 

 as not to be confided in. 



But I may further complain, that In the same Memoire of M. de Lisle, the 

 geography of my chart is called in question ; and we are told that I have placed 

 the entrance of the Magellan Straits at least 10 degrees more westerly than I 

 ought to have done: for that the ship St. Louis, in the year 1708, sailing from 

 the mouth of Rio Gallega, in about the latitude of 52° south, and not far from 

 Cape Virgin, directly for Cape Bonne Esperance (which course perhaps was 

 never run before) had found the distance between the two lands not more than 

 1350 leagues, which, he concludes, is much less than my chart of the varia- 

 tion makes it. I know not from what computation M. de Lisle has deduced 

 this consequence ; but I find by my chart, that I have made the longitude of 

 Rio Gallega 'Jb° west from London, and that of Cape Bonne Esperance \Q\ 

 east from it; that is in all Qii^ difference of longitude. This, with the two 

 latitudes, gives the distance, according to the rhumb-line 1364 leagues, but 

 according to the arc of a great circle, no more than 1287 leagues ; so that, in- 

 stead of invalidating what I have there laid down, it absolutely confirms it, as 

 far as the authority of one single ship's journals can do it. 



I do not pre fend that I have had observations made with all the precision 

 requisite to lay down incontestably the Magellan Straits, in their true geo- 

 graphical site; but yet it has not been without good grounds that I have placed 

 them as I have done. For when Sir John Narborough, in the year 1670, 



VOL. VI. Q . 



