It is well known that this gentleman was sent abroad by the public to make such geographical and astronomical observations as might facilitate the future practice of navigation, and particularly to determine the variation of the compass in such places as he should touch at, and, if {96} possible, to ascertain its general laws and affections. These things Dr. Halley, to his immortal reputation and the honour of our nation, in good measure accomplished, especially with regard to the variation of the compass, a subject, of all others, the most interesting to those employed in the art of navigation. He likewise corrected the position of the coast of Brazil, which had been very erroneously laid down by all former hydrographers; and from a judicious comparison of the observations of others, he happily succeeded in settling the geography of many considerable places where he had not himself been. So that the chart he composed, with the variation of the needle marked thereon, being the result of his labours on this subject, was allowed by all Europe to be far compleater in its geography than any that had till then been published, whilst it was at the same time most surprisingly exact in the quantity of variation assigned to the different parts of the globe; a subject so very intricate and perplexing, that all general determinations about it had been usually deemed impossible. But as the only means he had of correcting the situation of those coasts, where he did not touch himself, were the observations of others, when those observations were wanting, or were inaccurate, it was no imputation on his skill that his decisions were defective. And this, upon the best comparison I have been able to make, is the case with regard to that part of his chart, which contains the south coast of South America. For though the coast of Brazil, and the opposite coast of Peru on the South Seas, are laid down, I presume, with the greatest accuracy, yet from about the river of Plate on the east side, and its opposite point on the west, the coast gradually declines too much to the westward, so as at the Streights of Magellan to be, as I conceive, about fifty leagues removed from its true position; at least, this is the result of the observations of our squadron, which agree extremely well with those of Sir John Narborough. I must add that Dr. Halley has, in the philosophical transactions, given the foundation on which he has proceeded in fixing Port St. Julian in 76-½° of west longitude, which the concurrent journals of our squadron place from 70-¾° to 71-½°. This, he tells us, was an observation of an eclipse of the moon made at that place by Mr. Wood, then Sir John Narborough's lieutenant, and which is said to have happened {97} there at eight in the evening, on the 18th of September 1670. But Captain Wood's journal of this whole voyage under Sir John Narborough is since published together with this observation, in which he determines the longitude of Port St.