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Remarks on the Preceding Observations. By Professor J. D. Forbes. 



Mr Caldecott's observations possess an extraordinary interest from being 

 the first of the liind prosecuted between the tropics, from the great care and ex- 

 tent of the observations, and from the circumstances being altogether comparable 

 with those of observations lately made in Europe. [The depths of the thermo- 

 meters are the same as those at Brussels, Edinburgh, and Greenwich.] 



In conformity with Mr Caldecott's suggestion, I have had the cMrrected 

 means of 184:3—1-5 united, so as to give the mean temperature of each month 

 (the observations of 1842 being omitted). The results are given in the following 

 Table. The readings of Nos. I and 2 are deficient in some of the months, owing 

 to the liquid having risen above the scale : — 



Mean of Three Years, 1843 — 5. 



The following conclusions ai-e plainly deducible : — 



I. The Temperature of the ground at Trevandrum is from 5" to 6° Fahr. 

 liKjher than that of the air. This result is confirmed by observations on the tem- 

 perature of springs and wells at Trevandrum, which have been obligingly com- 

 municated to me by Major-General Cullen of the Madras Artillery. These 

 observations are printed in the " Proceedings" of this Society. 



II. When the monthly means of the thermometers are projected, so as to 

 shew the curves of annual temperature, they are found to have one great inflection 

 and a smaller one. The principal maximum of the temperature of the air occurs 

 about the beginning of April, after which the rainy season sets in, and the annual 



