The 5th at noon we got under sail in the road of Brest. I was obliged to cut my cable, because the fresh east-wind and the ebb prevented my tacking about, as I was apprehensive of falling off too near the shore. I had eleven commissioned officers, and three volunteers; and the crew consisted of two hundred sailors, warrant-officers, soldiers, boys, and servants. The prince of Nassau-Sieghen had got leave from the king to go upon this expedition. At four o’clock in the afternoon, the middle of the isle of Ushant bore N. by E. and from thence I took my departure.
Description of the Salvages.
During the first days, we had the wind pretty constant from W. N. W. to W. S. W. and S.W., very fresh. The 17th, afternoon, we got sight of the Salvages; the 18th, of the Isle of Palma; and the 19th, of the Isle of Ferro. What is called the Salvages, is a little isle of about a league in extent from E. to W. it is low in the middle, and at each end a little hillock; a chain of rocks, some of which appear above water, extend to the westward about two leagues off the island; there are likewise some breakers on the east-side, but they are not far from the shore.
Error in the calculation of the course.
The sight of these rocks convinced us of a great error in our reckoning; but I would not make a computation before I had seen the Canaries, whose position is exactly determined. The sight of the Isle of Ferro gave me with certainty the correction which I was desirous to make. The 19th, at noon, I took the latitude, and comparing it with the bearings of the Isle of Ferro taken that same hour, I found a difference of four degrees and seven minutes, which I was more to the eastward, than by my reckoning. This error is frequent in crossing from Cape Finisterre to the Canaries, and I had found it on other voyages, as the currents opposite the straits of Gibraltar set to the eastward with great rapidity.
Position of the Salvages rectified.
I had, at the same time, an opportunity of remarking, that the Salvages are improperly placed on M. de Bellin’s Chart. Indeed, when we got sight of them the 17th, after noon, the longitude which their bearings gave us differed from our calculation by three degrees seventeen minutes to the eastward. However, this same difference appeared the 19th of four degrees seven minutes, by correcting our place, according to the bearings of the isle of Ferro, whose longitude has been determined by astronomical observations. It must be observed, that during the two days which passed between our getting sight of the Salvages and of Ferro, we sailed with a fair wind; and consequently there can be very little miscalculation in that part of the course. Besides, the 18th, we set the Isle of Palma, bearing S. W. by W. corrected; and, according to M. Bellin, it was to bear S. W. I concluded, from these two observations, that M. Bellin has placed the Isle of Salvages about 32′ more to the W. than it really is.
I therefore took a fresh departure the 19th of December at noon. We met with no remarkable occurrences on our voyage, till we came to the Rio de la Plata; our course furnished us only with the following observations, which may be interesting to navigators.
1767.
January.
Nautical observations.
1. The 6th and 7th of January 1767, being between 1° 40′ and 0° 38′ north latitude; and about 28° longitude, we saw many birds, which induced me to believe, that we were near the rock of Penedo San Pedro; though M. Bellin does not mark it on his chart.