164 IV. CLIMATE. 



1. Assumed temperature for different altitudes. 



two yards of ascent. The conversion of altitude into its 

 corresponding temperature, or of temperature into its 

 corresponding altitude, will thus be greatly facilitated for 

 botanical purposes. Through this facility of mutual 

 conversion, it will become possible to compare the rela- 

 tive heights attained by plants under different latitudes 

 within Britain ; more especially so, if the centigrade 

 scale be used in making the needful allowance and 

 correction for diifereuces of latitude also. The two 

 Tables introduced above, 1 and 3, will suffice to exem- 

 plify this relation of temperature to altitude and latitude. 

 It is not to be expected, however, that any such uniform 

 rate will be exactly borne out by the ever-varied realities 

 of nature. But having observed and recorded facts for 

 its basis, the scale or rate will be found approximately 

 true as a general average, even although it should appear 

 decidedly untrue in some localities. 



In attempting to place plants according to their climatal 



