418 Action of the Atmoq)]iere vpofi newhj- deepened Soil. 



meters whose bulbs are sunk, one at the depth of 1 inch below 

 the soil, the other at the depth of 3'2 feet (being 3 French 

 feet) :— 



January . . 

 February 

 March 

 April 

 May . . 

 June 



July.. .. 

 August . . 

 September 

 October .. 

 November 

 December 



Thermometer sunk I inch. 



Mean ]Monthly 

 Reading. 



37-9 

 38-0 

 42'3 

 46-4 

 56-7 

 59-8 

 66-8 

 63-9 

 56-0 

 53-7 

 48-4 

 44-0 



Mean Daily 

 Range. 



Thermometer sunk 3'2 feet. 



Mean Blonthly 

 Reading. 



3 

 6 

 1 



4 

 2 

 7-2 

 5 

 3 

 9 

 7 

 6 

 '4 



Mean Daily 

 Range. 



0- 



0- 



0- 



0- 



0- 



0- 



0-5 



0-4 



0-3 



0-3 



0-3 



0-3 



A comparison of this last column, where the average daily 

 range is reduced to less than half a degree, with the column of 

 average daily range of temperature of the air in the shade, as ob- 

 served at Chiswick (p, 10), where it is seen to be generally above 

 20°, will give some idea of the widely different conditions of the 

 subsoil and the surface as to conditions of temperature. 



Josiah Parkes, in his observations on the Red Moss, Lanca- 

 shire, found that its temperature from 12 inches beneath the sur- 

 face, down to the bottom, was uniformly 46° F. " I never," 

 says he, " found any variation to occur in the results afforded by 

 thermometers placed at various depths during nearly three years' 

 observations, except in the winter of 1836, when the thermometer 

 nearest the surface sunk to 44° F. for a few days." The depth 

 of this bog, at the spot where the observations were taken, was 

 nearly 30 feet, and there were no springs in it, i^Eng. Agricult. 

 Journal, vol. v. p. 140.) 



From the statements given it is evident that the surface of the 

 ground, even in this climate, must be subject to a range of tempe- 

 rature of which the recorded observations of thermometers hung 

 in the usual manner give little conception. A comparison of the 

 daily readings of the wet bulb thermometer, with those of one 

 hung in the sun with the ball blackened, would give a better idea 

 of the daily variation. But the ground at a foot deep in this 

 country appears to be scarcely affected by frost, unless where it 

 has been loosened up by the plough or spade, 



Ihe action of frost upon the raw mineral matter constituting 

 newly exposed soil is of the utmost importance. This mineral 

 matter consists of the debris of the various rocks which are found 



