On the 25th we crossed the Line with the usual ceremonies, in longitude 29 deg. 30’, when, by the result of several very good azimuths, the variation was 2 deg. 24’.

On the 28th, at noon, being in the latitude of Ferdinand Noronha, and, by the mean of several observations by Mr Green and myself, in longitude 32 deg. 5’ 16” W. which is to the westward of it by some charts, and to the eastward by others, we expected to see the island, or some of the shoals that are laid down in the charts between it and the main, but we saw neither one nor the other.

In the evening of the 29th, we observed that luminous appearance of the sea which has been so often mentioned by navigators, and of which such various causes have been assigned; some supposing it to be occasioned by fish, which agitated the water by darting at their prey, some by the putrefaction of fish and other marine animals, some by electricity, and others referring it to a great variety of different causes.  It appeared to emit flashes of light exactly resembling those of lightning, only not so considerable, but they were so frequent that sometimes eight or ten were visible almost at the same moment.  We were of opinion that they proceeded from some luminous animal, and upon throwing out the casting-net our opinion was confirmed:  It brought up a species of the Medusa, which when it came on board had the appearance of metal violently heated, and emitted a white light:  With these animals were taken some very small crabs, of three different species, each of which gave as much light as a glow-worm, though the creature was not so large by nine-tenths:  Upon examination of these animals, Mr Banks had the satisfaction to find that they were all entirely new.[70]

[Footnote 70:  The reader is referred to the account of Captain Krusenstern’s circumnavigation, for a very satisfactory relation or an experiment on this subject, which clearly proves the truth of the opinion above stated, as to the cause of the shining appearance so often noticed at sea.  It is too long for quotation in this place.—­E.]

On Wednesday the 2d of November, about noon, being in the latitude of 10 deg. 38’ S. and longitude 32 deg. 18’ 43” W. we passed the Line, in which the needle at this time would have pointed due north and south, without any variation:  For in the morning, having decreased gradually in its deviation for some days, it was no more than 18’ W. and in the afternoon it was 34’ east.

On the 6th, being in latitude 19 deg. 8’ south, longitude 35 deg. 50’ west, the colour of the water was observed to change, upon which we sounded, and found ground at the depth of thirty-two fathoms; the lead was cast three times within about four hours, without a foot difference in the depth or quality of the bottom, which was coral rock, fine sand, and shells; we therefore supposed that we had passed over the tail of the great shoal which is laid down in all our charts by the name of Abrothos, on which Lord Anson struck soundings in his passage outwards:  At four the next morning we had no ground with 100 fathom.