MARINE BAROMETER. 175 



rainy monsoon, which may perhaps account for the descent of observations 



the mercury independently of the direction of the wind. and inferences 



2d. On the confirmation of the nort:,-west monsoon, there ^° ascertain the 



correspondent 

 was a change in the barometer at the head of the gulph, the changes of 



common standard of the mercury being at 29,88; but during; windand wea- 

 , , . .,,,,.,. , ,. r'her, to be ex- 



the times ot heavy ram, with thunder, hghtning, and squalls or pected after 



wind, when amongst the islands of Cf»pe Vanderiin, the mean change in th« 

 height was 29,79. The north-west monsoon, after coming j^^i^x. 

 over Arnhem's Land, blows along the shore for a considerable 

 part of the space between the Cape Maria and Cape Van Die- 

 men, of Tasman ; and during the examination ot the parts so 

 circumstanced, we sometimes had tolerably fine weathur, and 

 the mercury above 29,90; but the wiad was then usually more 

 from the north than when the mercury stood lower. As we 

 approached Cape Maria, and the bight between it and the 

 south side of Groote Eyland, the mercury stood gradually 

 lower; and in the bight, where the north-west monsoon came 

 directly from off the shore, although we had sea and land 

 breezes with fine weather, according to Mr. Dalrymple's 

 general position, yet the mercury was uncommonly low, its 

 range being from 29,63 to 29,81 : the average 2J,74, be!ow 

 what it had stood in the very bad weather near Cape Vander- 

 iin. These winds and weather, and the low state of the mer- 

 cury, continued until we got without side of Groote Eyiand. 



3d. On the east side of Groote Eyland, and the west side 

 of the gulph, northward from that island, we sometimes had 

 sea and land breezes with fine weather; we had also two mo- 

 derate gales of wind from the eastward, of from two to four 

 days continuance each, with one of which there were heavy 

 «qualls of wind and rain ; sometimes also, the winds were tole- 

 rably steady between north and west, with fine weather. Du- 

 ring all these variations, the mercury never differed much from 

 its average standard 29,90; and it seemed as if the increase of 

 density in the air, from the wind blowing upon the coast, was 

 equal to its diminution of quantity from the fall of rain and 

 strength of the wind; and, on the other side, that the wind 

 Trom over that corner of Arnhem's Land permitted the mer- 

 cury to descend, as much as the fine weather would otherwise 

 have occasioned it to rise. 



Upon the north side of Grpote Eyland, the mercury stood 



higher 



