34 On the land ivinds of CoromandeL \ [Jan. 



for moisture, the deposition would be slower, and the eva- 

 poration so much quicker, that the one would counter- 

 balance the other and indicate a state of perfect dryness. 

 Our reason informs us this is impossible, and consequently, 

 that there must be some source of fallacy, either in the in- 

 strument or in the mode of conducting the experiment,which 

 has not been guarded against. Such I conceive to have been 

 the case in Mr. Malcolmson's experiments, and believe that 

 we must before we can arrive at accurate results isolate the 

 dry or naked ball of the instrument, so as to prevent, rapid 

 evaporation from its surface, since the same cause acting at 

 the same time, on both balls of the instrument, must neces- 

 sarily produce the same effect on both, namely, evaporation, 

 and if the evaporation equals or exceeds the rapidity of depo- 

 sition, absolute dryness will be indicated though the case 

 may be far otherwise, The correctness of the theory there- 

 fore remains unaffected by these experiments, while to my 

 mind the facts adduced in support of it leave no doubt of its 

 affording the true explanation of the cause of the hot land 

 winds. 



Between the meridians of Courtallum and Tutecoreen, we 

 can actually trace them from their origin to their termina- 

 tion. The same causes are in operation from Cape Comorin 

 to. the head of the gulf of Cambay. So long as the south- 

 west monsoon prevails, the temperature on the west coast is 

 considerably lower than on the east, and the air loaded with 

 vapour, and so long is the whole country to the eastward of 

 the Malabar mountains subject to visitations of the land 

 winds : more or less modified by local causes ; but the prin- 

 ciple is the same throughout, and similar in kind to that 

 which produces the changes of the monsoons themselves ; 

 namely, the action of solar heat, on extensive tracts of 

 country, producing local atmospherical rarification, and its 

 consequences a rush of denser air to restore the equilibrium 

 from parts not subjected to the same influence. 



Palamcottah, 3lst October, 1835. 



Note,— Since writing the above I find in Myers' System 

 of Geography a reference to " Roxburgh's Essay on the 

 Land Winds of Coromandel." This essay I have not seen, 



