Page:Philosophical Transactions - Volume 096.djvu/303

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on the Marine Barometer.

on account of the decayed state of the Investigator, which obliged me to return with all practicable expedition to Port Jackson. An abridged statement, however, of the general height of the mercury under the five following circumstances, will afford some light upon the subject, and perhaps not be uninteresting. 1st On the east side of the gulph, and at the head, with the south-east monsoon, or trade wind. 2d. At the head of the gulph with the north-west monsoon. 3d. On the west side during the north-west monsoon. 4th. At Cape Arnhem under the same circumstance; and 5th. In the passage from Cape Arnhem, at a distance from the coast, to Timor, with variable winds.

In a memoir written by Alexander Dalrymple, Esq. F.R.S. respecting the Investigator's voyage, there is this general remark:—" Within the tropics, the monsoon blowing on the coast produces rainy weather, and when blowing from over the land, it produces land and sea breezes." This I found verified on the east side of the gulph of Carpentaria, between Nov. 3 and 16, which time was employed in its examination; for though we had found the south-east trade to blow constantly on the east side of Cape York just before, and doubtless it did so then, yet in the gulph we had a tolerably regular sea breeze, which set in from the westward at eleven or twelve o'clock, and continued till seven t eight, or nine in the evening. Towards the head of the gulph, the trade wind, which blew at night and in the morning, came more from the NE, and the sea breezes more from north and NW, but without producing any regular alteration in the height of the mercury, whose average standard was 29,95: it never fell below 29,90 or rose above 30,04. At the head,