536 SUBTERRANEAN TEMPERATURE IN THE 



with the sienite, numerous small streams were flowing out into 

 the shaft. In the lowest of these the thermometer was exposed 

 until its temperature became stationary. The following was the 

 accordant result of several such observations : 



Depth. Temperature. 



760 feet, 68.° 75 



3. Mid Lothian Neiv Shaft (1842). This shaft, in the same 

 field with the preceding, and near it, had at the time of my ob- 

 servations reached the depth of 600 feet. Near the bottom it 

 passed through a thin seam of coal and coal shale, in all about 

 six feet, and beneath this to the bottom, a distance of about ten 

 feet, it exposed dark argillaceous slates, the main mass of coal 

 not having then been attained. 



At a point 330 feet'below the top of the shaft, a beautiful and 

 rather bold spring issues from the sandstone, which is conducted 

 downwards by a gutter cut in a spiral form around the shaft. 

 The temperature of this stream, where it first appears, was care- 

 fully measured, and found to be 61.° 75. At the bottom, numer- 

 ous very small streams come in from the rock. These all agi'eed 

 in giving the temperature 66.° 25, which I therefore infer to be 

 very nearly the temperature of the strata at that depth. The very 

 copious drippings from above, together with the spring before 

 noticed, blending with the infiltration from the strata near* the 

 bottom, formed a considerable pool, requiring the active use of 

 the buckets. The temperature of this mixed water I found to 

 be 63.° 5. 



At the time of these observations only two hands were at work 

 in the shaft, and there had been no blasting for some time before 

 I descended. I therefore consider the observations on the spring 

 at 330 feet, and the small sti-eams at the bottom, to be as accurate 

 indications of the temperatures at those depths as this or perhaps 

 any other method of examination admits of. We have therefore 

 in this shaft — 



Depth. Temperature. 



330 feet, 61." 75 



600 " 66." 25 



