174 



Mr. E. Hull on the Temperature of Strata. [Jan. 27, 



result obtained by Professor Phillips, F.R.S., at the Monkwearmouth 

 Colliery. 



Since the time abore referred to, the proprietor of the Rose Bridge Col- 

 liery, Mr. J. Grant Morris, determined to carry down the shafts from the 

 ■ Cannel" seam to the ■ Arlev " seam of coal, which was known to lie 

 more than 200 yards below it ; and consequently in the spring of 1S6S 

 preparations were commenced for carrying out this project. In the incre- 

 dibly short time of one year and two months the Arley coal was struck, 

 and was found to be of good thickness and quality. The total depth reached 

 was SOS yards, and the ultimate temperature in the coal itself was found 

 to be 93j z F. The manager of the colliery, Mr. Bryham, sensible of the 

 Talue of observations on the temperature of the strata at such unusual 

 depths (this being probably the deepest colliery in the world, certainly in 

 Britain), made a series of observations with as much care as the circum- 

 stances would admit, and has entrusted them to me for publication. 



The mode of taking the observations was as follows : — On a favourable 

 stratum, such as shale, or even coal, having been reached, a hole was 

 drilled with water in the solid strata to a depth of one yard from the 

 bottom of the pit. A thermometer was then inserted, the hole having 

 been sealed and made airtight with clay. At the expiration of half an hour 

 the thermometer was taken up and the reading noted. 



It might possibly be objected that the time allowed (thirty minutes) was 

 insufficient for the imbedding of the thermometer, and that the readings 

 are liable to error from this cause. I feel sure, however, that if any error 

 has arisen it is inappreciable, and does not in the least invalidate the ge- 

 neral result. In fact I am assured by Mr. Bryham that, from actual test- 

 ing on several occasions, he found less than this time of thirty minutes suf- 

 ficient for the purpose required. 



While the temperatures of the strata were being measured, observations 

 were also carried cn pari passu on those of the open pit during the descent. 

 These are given in the Table annexed. By a comparison of the results in 

 the two columns, it will be observed that as the depth increased the differ- 

 ences between the corresponding temperatures in the pit and the strata 

 tended to augment ; in other words, the temperature of the strata was 

 found to augment more rapidly than that of the open pit. 



The effects of the high temperature and pressure on the strata at the 

 depth of 2425 feet are, as I am informed by Mr. Bryham, making them- 

 selves felt, and cause an increase in the expense both of labour and timber 

 for props. This colliery, in fact, will be in a position to put to the test our 

 views and speculations on the effects of high temperature and pressure on 

 mining operations. 



Iu order to obtain the average rate^f increase of heat, as shown by the 

 experiments at Rose Bridge Colliery, we may assume < in the absence of 

 direct observation) the position and temperature of the invariable stratum 

 to be 50 feet from the surface and 50 c F., Tthich is probably nearly the 



