MARINE BAROMETER. 113 



it now came on to blow fresh, with squally thick weather^ observations 

 yet the mercury continued nearly stationary for twenty- and inferences 

 four hours, appearing to be kept up in consequence of the Jhrcorrespon- 

 wind having shifted round to SSW, more directly from oif dent changes 

 the sea. On its increasing to a gale, however, there was "^ '^'^'"^^ ^"^ 



wcHtiier to DC 



a pretty rapid descent in the barometer to 29,96 ; but the expected after 



ascent again was equally rapid, and to a greater height, on change in the 



the wind becoming moderate. In a short calm that succeed- "^^""'^ ^^^'°' 



J ° meter. 



ed, the mercury stood at 30,4^2, but on the Avind setting in 



from the north, which was from otf the land, it fell to 30,25, 



and remained there two days : we had then reached Bass' 



Strait. 



From these examples upon the south coast, it appears, 

 generally, that a change of wind from the northern, to any 

 point in the southern half of the compass, caused the mer- 

 cury to rise, and a contrary change to fall ; and that the 

 mercury stood considerably higher when the wind was from 

 the south side of east and west, than, in similar weather, it 

 did when the wind came from the north side ; but, until it is 

 known what arc the winds that occasioned the mercury to 

 ascend, and what to descend, upon the other coasts of 

 Australia, it will probably be not agreed, whether it rose in 

 consequence Of the south winds bringing in a more dense air 

 from the polar regions, and fell on its being displaced by that 

 which came from the Tropic ; — or whether the rise and 

 higher standard of the mercury was wholly, or in part, occa- 

 sioned by the first being sea winds, and the descent because 

 those from the northward came from off the land. 



The height, at Avhich the mercury generally stood upon 

 the south coast, seems to deserve some attention. It was 

 very seldom down to 29,40, and only once to 29,42. Of 

 one hundred and sixty days, from the beginning of Decem- 

 ber to May, it was nearly one-third of the time above 30 

 inches ; and the second time of passing along the coast, 

 from the 16th of May to the 1st of June, it only descended 

 to 29,96, and that for a few hours only, its average standard 

 for these sixteen days being 30,25. Upon the eastern half 

 of the coast, beyond Cape Catastrophe, in March, April, 

 and May, the mercury stood higher than it did on the 

 western half in December, January, and February : the 

 average standard of the first was 30,09, but that of the 



Vol. XVr.-rFrB. 1807. L latter 



