118 TABLES OF TEMPEBATURE. 



does not comprise all that could be wished, yet it would form a 

 good basis. 



The larch is now planted as a shelter for the oak, but on its 

 introduction from Italy it was kept in a greenhouse for years. 

 Such unnecessary precautions, it may be said, are now obsolete ; 

 but I may be allowed to remark that, in the absence of data for 

 estimating the temperatures of particular localities, mucli injury 

 may be done, even at the present day. For example : gardeners 

 often receive plants or packets of seeds with no information re- 

 specting them, except, perhaps, the name of the country in which 

 they were originally obtained. If from within the tropics, the 

 gardener is apt to conclude that the plant must require to be 

 placed in a stove. Madras is within the tropics, in lat. 1 3° 4', 

 its mean temperature about 82° ; that of the coldest month, 76.^° ; 

 and that of the hottest, 87° or 88° ; so that a plant from thence 

 is certainly a stove-plant. Another place, called Dodabetta, still 

 nearer the equator, being in lat. 1 1° 23', might be supposed to 

 be fully hotter; but there is a wide difference. At Dodabetta 

 the mean temperature of the year is only 52° 17', being no fewer 

 than 30° below that of Madras. The mean temperature of the 

 hottest month at Dodabetta is 56;^^, and the thermometer in the 

 shade, during two years' observations, never rose above 69°. In 

 the Garden of the Society at Chiswick, the mean temperature of 

 the hottest month averages about 63° ; for months the daily 

 maximum averages above 70° ; and instead of never exceeding 

 69°, as at Dodabetta, the temperature in the shade at Chiswick 

 has occasionally exceeded 90=. The climate of Ciiiswick is, 

 therefore, too hot in summer for plants indigenous to Dodabetta, 

 and these would certainly be killed if confined in a stove. 



The discrepancy between the temperatures of Madras and 

 Dodabetta is owing to difference of elevation, Madras being 

 near the level of the sea ; whereas Dodabetta is situated on the 

 Neilgherry Hills, at an elevation of 8640 feet. Elevation is so 

 important with regard to temperature, that tlie impossibility of 

 ascertaining it for insertion for every place in the following 



