94 AGRICULTURE. 



that sunny clime he found the mean heat of soil, at that 

 depth, to be at noon, for six successive months, 131. If 

 that were his mean heat for six months, we cannot doubt 

 that it is frequently obtained as an extreme heat in the 

 hottest portion of our year in England. Mr. Parkes gives 

 temperatures on a Lancashire flat moss, but they only 

 commence at 7 inches below the surface, and do not extend 

 to midsummer. At that period of the year the temperature 

 at 7 inches never exceeded 66, and was generally from 

 10 to 15 below the temperature of air in the shade, at 4 

 feet above the earth. At the depth of 13 inches the soil 

 was generally from 5 to 8 cooler than at 7 inches. Mr. 

 Parkes's experiments were made simultaneously on a 

 drained and on an undrained portion of the moss; and 

 the result was, that, on a mean of 35 observations, the 

 drained soil at 7 inches in depth was 10 warmer than the 

 undrained at the same depth. The undrained soil never 

 exceeded 47, whereas after a thunder-storm the drained 

 reached 66 at 7 inches, and 48 at 31 inches. Such were 

 the effects at an early period of the year on a black bog. 

 They suggest some idea of what they are, when in July or 

 August thunder- rain at 60 or 70 falls on a surface heated 

 to 130, and carries down with it into the greedy fissures 

 of the earth its augmented temperature. These advantages 

 porous soils possess by nature, and retentive soils only 

 acquire them by drainage.* 



* The only temperature of thunder-rain given in Mr. Parkes's Tables 

 is 78. This, we imagine, must be an extreme heat. We have heard, 

 with much satisfaction, that Mr. Parkes is, by means of his numerous 

 staff stationed at the works which he is carrying on in many parts of 

 Great Britain, Ireland, and (we believe) France, conducting a series of 

 experiments on the temperatures of water of drainage, which tend to 

 show an increase in some proportion to the length of time for which 

 the drainage has been executed. We know no experiments connected 

 with agriculture to the result of which we look with more hopeful 

 expectation. Any agriculturist may, by means of a delicate thermo- 

 meter, conduct and record such observations on his own farm. Probably 

 the water of drainage from firm land may be expected to be higher in 

 temperature than that from the quoted bog in summer, and lowfer in 

 winter. 



