129 



The following remarks in Major-General CuUen's letter illustrate 

 some particulars of the observation. 



" In a dry season the spring sometimes ceases altogether, but it is 

 very singular, that on its reappearance after a few days' rain, its tem- 

 perature continues the same nearly as before. 



"Ihad supposed that the temperature of such a spring, as that shewn 

 by Mr Caldecott's ground-thermometers, would have been nearly the 

 mean annual temperature of the atmosphere at the place of observa- 

 tion, but I perceived that his mean annual temperature for Trevan- 

 drum is only about 80° ; but Colonel Sabine has already pointed out 

 some peculiarities in the meteorology of Trevandrum which may have 

 a wider application than has hitherto been suspected. The early sea 

 breezes which affect the barometer, &c., may not extend their effect 

 below the surface of the ground. 



" Even the temperature of the wells is remarkably uniform, though 

 lower than that of the spring. In none does the monthly tempera- 

 ture differ above 1° from the annual. The kitchen and village well 

 are upon the top of a swell, while the garden-well is on a consider- 

 ably lower level, down a slope half-way down to the spring, and the 

 average depth of water of the garden-well is also greater than the 

 other two. May these differences account for the higher temperature 

 of the garden-well 1 The depth from the surface of the ground of all 

 the wells was nearly alike, 40, 48, and 36 feet." 



4. Chemical Notices. By Professor Gregory. 



(1.) On a Fatty Substance derived from Animal Matter. 

 This substance, derived from a pig buried for fifteen years on the 

 side of a hill, was found to consist of free fatty acids, with a mere 

 trace of animal matter, and no appreciable trace of phosphate of 

 lime. The bone earth appears to have been dissolved by the water 

 percolating through the soil. 



(2.) On a Black Powder ivhich appeared on the Surface of Loch 

 Dochart, on the morning of 2^d November 1846. 



This powder was found to have the composition of humus in a 

 very advanced state of decay, and was probably derived from peat. 

 It contained 77 per cent, of carbon ; and left, when burned, hardly a 

 trace of ashes. 



