with Geographic Botany. — Temperature. 1 7 1 



out a number dependent on the proportionate influence of 

 these agents, and the prominent climates of many parts of the 

 world may be shortly and effectively expressed. This method 

 is entirely independent of latitude or geographical position, 

 and refers solely to the condition of the climate as it actually 

 exists, depending on local influences. Sixteen climates of this 

 kind may then be formed, each of which is easily expressed, 

 and, from the examples adduced it may be stated, coincident 

 with a peculiar vegetation. 



Climates. 

 Mean temp. 70°— 84°. 

 Hot and dry climate ; seasons in extremes, ex. 

 Hot and dry climate ; seasons even, ex. Arabia. 

 Hot and moist climate; seasons in extremes, ex. China. 

 Hot and moist climate ; seasons even, ex. Malay islands. 



Mean temp. 55°— 70°. 

 Warm and dry climate ; seasons in extremes, ex. Asia Minor. 

 Warm and dry climate ; seasons even, ex. Egypt. 

 Warm and moist climate ; seasons in extremes, ex. Southern 



States of America. 

 Warm and moist climate ; seasons even, ex. Canaries. 



Mean temp. 45°— 55°. 

 Temperate and dry climate ; seasons in extremes, ex. 

 Temperate and dry climate ; seasons even, ex. 

 Temperate and moist climate ; seasons in extremes, ex. 

 Temperate and moist climate ; seasons even, ex. England. 



Mean temp. 45°— 32°. 

 Cold and dry climate ; seasons in extremes, ex. Canada. 

 Cold and dry climate ; seasons even, ex. 

 Cold and moist climate ; seasons in extremes, ex. Siberia. 

 Cold and moist climate ; seasons even, ex. North of Scotland. 



There is, however, in spite of all local causes, a certain re- 

 lation between the temperature and the latitude; from the 

 equator to the poles a gradual decrease takes place. Rather 

 conflicting statements have been made respecting the mean 

 temperature at the equator. Mr. Atkinson has fixed it as 

 high as 86°*55, which is certainly in excess; Mr. Kirwan 

 gives 84°; Sir John Leslie 84°*2 ; Mr. Forbes 81°*5 ; and 

 Humboldt also 81°-5. The latter have been considered as 

 too low, but the last-mentioned authority continues to main- 

 tain his original opinion. I was induced to consider, that in 

 the absence of a regular series of observations, the mean heat 

 of the day, when the sun was in or near the zenith, would at 

 least give the possible extreme of the greatest annual mean 



N 2 



