2 INTRODUCTION. 



climate of any locality — the most useful kind of 

 information, it must be acknowlcdo-cd, that can 

 be acquired in relation to cultivatable objects. 

 As a rule of guidance, I may mention it is com- 

 puted, that advancing beyond the temperate zone 

 towards the equator, at the level of the sea a 

 degree of temperature will be gained for every 

 degree of latitude passed over ; and, on the con- 

 trary, every degree of latitude, from the temperate 

 regions towards either pole, is distinguished by 

 the loss of a corresponding amount of heat. This, 

 however, it must be observed, being estimated 

 entirely on the same level, will be liable to in- 

 terruption from the physical character of most 

 countries, more especially of those which offer 

 the most encouragement to the spread of Orchi- 

 dacccc; indeed, the variety of temperature and 

 climate presented by a mountainous country, is 

 almost beyond calculation, quite precluding the 

 possibility of any latitudinal estimate, except as 

 a mean, for the base or table land: from whence, 

 as w^e ascend the hills, the temperature is found 

 to decrease in the proportion of about one degree 

 for every hundred feet of elevation ; information 

 on this point, however, is unfortunately but scan- 

 tily furnished, and some discrepancy also existing 

 in that made known renders a correct computa- 

 tion rather difficult. Still, the above formula 

 will, perhaps, be sufficient for ordinary stations, 



