CLIMATE. 71 



Encyclopedia, after an elaborate consideration of the various 

 proposed methods, gives the- preference to the mean of the 

 daily extremes. According to this calculation, the mean of 

 the daily extremes for 25 months is 58°'68 which we there- 

 fore assume as the mean annual temperature of Ootacamund. 

 The next most important consideration is the diurnal range 

 of the thermometer. From what has been stated of the 

 calorific power of the sun's rays, and the contrary effects of 

 radiation of great elevations, we must expect this to be con- 

 siderable. Accordingly, we find that it occasionally is as 

 much as 24°, (January, 1832,) precisely in the season when 

 the above causes operate most powerfully ; and that in July, 

 when they come least into play, it is still 10°. Subjoined is 

 the daily range for nine months of this year, which may be 

 considered as an average season : 



January, 20'40 June, 15'59 



February, 20-33 July, 10-29 Minimum. 



March, 23-33 Maximum. August, 15-22 



April, 19-73 September, 11-73 



May, 16-48 



Giving a general mean of 17-01. 



The greatest observed annual range (but in different years) 

 appears to be 38° (viz. between 39° and 77°.) The mean 

 annual range for part of three years is as follows : 

 For 1831, 15-20 



1832, 18-33 



1833. 17-01 



It is important to remark, that this range is still betwixt 

 two points, which occur frequently in temperate climates, and 

 is certainly less than what prevails in most of them. The 

 maximum observed is 77 , only 2° above what is assumed as 

 summer heat in England, and the minimum 38° is much 



