717 



the study of the atmospheric tides, I ventured 

 to predict that " in the temperate climates, 

 where the horary variations of the weight of the 

 air are concealed beneath a multitude of local 

 causes that make the barometer rise and fall 

 irregularly, the mean, drawn from a great num- 

 ber of observations made from hour to hour, 

 proves that, in the high latitudes, like those of 

 the torrid zone, the mercury rises and sinks at 

 determinate epochas." That proof, thanks to 

 the zeal of naturalists, has been completely ob- 

 tained. We shall follow the variations of the 

 tropics towards the temperate zones. M. Si- 

 monoff has observed that the hours of the max- 

 ima and the minima are manifested by partial 

 observations, and without having recourse to 

 the mean, in the Pacific Ocean, between the 

 tropic of Capricorn, and the 30° of the south 

 latitude ; and in the Atlantic Ocean, between 

 the tropic of Cancer, and the 26° of north la- 

 titude. If the greater extension of the tropical 

 climate in the southern hemisphere, be confirm- 

 ed by other travellers, it will be linked with 

 many phenomona which the temperature, the 

 trade-winds, and the vegetation of monocoty- 

 ledon arborescent plants, present. Mr. Hors- 

 burgh found on the east of Africa, in the seas 

 of India and China, that the variations were 

 more regular, and greater, from 10° north lat. 

 to 25° south lat., than from 10° to 20° north of 



