At nine o'clock in the evening on the 10th,[79] we saw the island of Bonavista bearing south, distant little more than a league; though, at this time, we thought ourselves much farther off: But this proved a mistake. For, after hauling to the eastward till twelve o'clock, to clear the sunken rocks that lie about a league from the S.E. point of the island, we found ourselves, at that time, close upon them, and did but just weather the breakers. Our situation, for a few minutes, was very alarming. I did not choose to sound, as that might have heightened the danger, without any possibility of lessening it. I make the north end of the island of Bonavista to lie in the latitude of 16° 17' N., and in the longitude of 22° 59' W.
[Footnote 79: As a proof of Captain Cook's attention, both to the discipline and to the health of his ship's company, it may be worth while to observe here, that it appears from his log-book, he exercised them at great guns and small arms, and cleaned and smoked the ship betwixt decks, twice in the interval between the 4th and the 10th of August.--D.]
As soon as we were clear of the rocks, we steered S.S.W., till day-break next morning, and then hauled to the westward, to go between Bonavista and the isle of Mayo, intending to look into Port Praya for the Discovery, as I had told Captain Clerke that I should touch there, and did not know how soon he might sail after me. At one in the afternoon, we saw the rocks that lie on the S.W. side of Bonavista, bearing S.E., distant three or four leagues.
Next morning, at six o'clock, the isle of Mayo bore S.S.E., distant about five leagues. In this situation we sounded, and found ground at sixty fathoms. At the same time the variation, by the mean of several azimuths taken with three different compasses, was 9° 32 1/2' W. At eleven o'clock, one extreme of Mayo bore E. by N., and the other S.E. by S. In this position, two roundish hills appeared near its N.E. part; farther on, a large and higher hill; and, at about two-thirds of its length, a single one that is peaked. At the distance we now saw this island, which was three or four miles, there was not the least appearance of vegetation, nor any relief to the eye from that lifeless brown which prevails in countries under the Torrid Zone that are unwooded.
Here I cannot help remarking that Mr Nichelson, in his Preface to "Sundry Remarks and Observations made in a Voyage to the East Indies,"[80] tells us, that "with eight degrees west variation, or any thing above that, you may venture to sail by the Cape de Verde Islands night or day, being well assured, with that variation, that you are to the eastward of them." Such an assertion might prove of dangerous consequence, were there any that would implicitly trust to it. We also tried the current, and found one setting S.W. by W., something more than half a mile an hour. We had reason to expect this, from the differences between the longitude given by the watch and dead reckoning, which, since our leaving Teneriffe, amounted to one degree.
[Footnote 80: On board his majesty's ship Elizabeth, from 1758 to 1764; by William Nichelson, master of the said ship.--London, 1773.]
While we were amongst these islands, we had light breezes of wind, varying from the S.E. to E., and some calms. This shews that the Cape de Verde islands are either extensive enough to break the current of the trade wind, or that they are situated just beyond its verge, in that space where the variable winds, found on getting near the Line, begin. The first supposition, however, is the most probable, as Dampier found the wind westerly here in the month of February; at which time the trade wind is supposed to extend farthest toward the equinoctial.[81] The weather was hot and sultry, with some rain; and, for the most part, a dull whiteness prevailed in the sky, that seems a medium between fog and clouds. In general, the tropical regions seldom enjoy that clear atmosphere observable where variable winds blow; nor does the sun shine with such brightness. This circumtance, however, seems an advantage; for otherwise, perhaps, the rays of the sun, being uninterrupted, would render the heat quite unsupportable. The nights are, nevertheless, often clear and serene.
[Footnote 81: Dampier's Voyages, vol. iii. p.10.--Captain Krusenstern appears to be of the same opinion, as to the Cape de Verde islands being of sufficient magnitude to alter the direction of the trade winds, remarking that S.W. winds are frequently met with there, and that if they are not, the wind is always very moderate in their vicinity. He recommends vessels, on their passage to the equator, to take their course to the westward of these islands, so as to cross the parallel of 17°, or that of the island of Antonio in 26-1/2°, or even that of 27°, and then to steer S.E. by S. directly to the equator. He further advises, that, if possible, the passage of the Line be effected in 20° or 21°, as then there is the advantage of a directly free wind as soon as the S.E. trade sets in, and of course the ship gets quicker to the southward. But this can rarely be done. He himself crossed the equator in 24° 20' W., after a passage of thirty days from Santa Cruz. Ships, he informs us, when crossing in a more westerly direction than 25° and 26°, have been driven by strong currents, and a too southerly trade wind, so near the coast of Brazil, as not to be able to clear Cape St Augustin. The present opportunity is taken of mentioning, that this very cautious and intelligent navigator agrees, in general, with Cook, as to Nichelson's rule. "His instructions for crossing the Line, on the voyage to India, with 6° 30' and 7° 00' west variation, but in returning to Europe, with eight degrees, might have been of use forty years ago, when the method of finding the longitude at sea by distances of the sun and moon was known to very few navigators, and for a time no great error was committed by pursuing them; but at present a variation of seven degrees would hardly be found on the coast of Africa."--The reason is, as the scientific reader must know, that the variation has been on the western increase since the period alluded to. Thus Nichelson found it at St Helena, in 1764, to be 11° 38', and Captain Krusenstern, in 1806, a space of forty-two years, 17° 18' 10".--E.]
At nine o'clock in the morning of the 13th, we arrived before Port Praya, in the island of St Jago, where we saw two Dutch East India ships, and a small brigantine, at anchor. As the Discovery was not there, and we had expended but little water in our passage from Teneriffe, I did not think proper to go in, but stood to the southward. Some altitudes of the sun were now taken, to ascertain the true time. The longitude by the watch, deduced therefrom, was 23° 48' west; the little island in the bay bore W.N.W., distant near three miles, which will make its longitude 23° 51'. The same watch, on my late voyage, made the longitude to be 23° 30' W.; and we observed the latitude to be 14° 53' 30" N.
The day after we left the Cape de Verde islands, we lost the N.E. trade wind; but did not get that which blows from the S.E. till the 30th, when we were in the latitude of 2° north, and in the twenty-fifth degree of west longitude.