98 Summary/ Revien- of the late Investigations 



Abbreviations employctl in the preceding Table: 

 a. air; e. earth, inckiding tiie rock of the walls and floors of the gal- 

 leries; w. water; A. adit; S, shaft; E. S. engine-shaft; R relinquished 

 part of the mine; W working part, the figures between parentheses, as 

 (10), denote the distance from the engine-shaft, in fathoms, of the part of 

 the mine at which the temperature was taken, and this either in an east 

 (e.) west (w.) or north-west (nw.) direction. 



Notes to the preceding Table. 



* " At the depth of nine fathoms in the engine shaft, the steam arising 

 was so dense that our candles were of little use: it had the temperature of 

 74°, and was extremely oppressive, which induced us to descend by another 

 route." 



■j- " The adit is 32 fathoms deep: the water here (at the distance of 260 

 fiithoms from the mouth of the pump by which it is drawn up) was 54°; 

 but it gradually increased in temperature from this place to the mouth of 

 the pump, where it was 56°." 



X " To show the influence of a few (three) persons on the temperature 

 of the air of a small mine, I found the air in the adit, on our return, 1° 

 warmer than at our descent.'' 



§ " Neither of these spots were working places, but the latter was more 

 contiguous to them than the others." 



II This was in a confined end; here the water issuing from two small 

 veins, a few feet apart, indicated the above temperatures. 



" Since the temperature of the diiFerent parts of this mine[Oatfield] has been 

 taken, the pumps have been drawn up from the deepest part, and the shaft, 

 below the depth of 182 fathoms, has been for some months full of water. At 

 this level the temperature was previously 77°; but a few months afterward 

 (Sept. 1822), when the water had risen to the level, its temperature, a few 

 feet below its surface, was 69°; and at the depth of 12 feet in the water, 

 it was 71°. A fortnight after this I repeated the experiment, and found the 

 temperature, a few feet below the level, 66°; and at 12 feet deep in the 

 water 67°. This shows that the water is gradually cooling, and becoming 

 of the temperature of the surrounding earthy strata, it having cooled 3° in 

 a fortnight, and 1 1° since its admission into the shaft." 



^ " I have since ascertained the temperature of three levels which have 

 been driven from Crenver, directly under the deepest level in Trenoweth. 

 At the depth of 124 fathoms [below the adit-level] it was 57°,— at 132 

 fathoms, 58°,— at 142 fathoms 58°. Five months before, when the miners 

 were at work in the last-mentioned level, the temperature was 68°. To 

 what then must we attribute that superiority of temperature ?" 



*• " At 232 fathoms deep, at the extremity of the level, on a Monday 

 morning, before the workmen had returned to labour, and wliere a machine 

 was erected for blowing fresh air to the miners, the thermometer stood at 

 90° ; but a few days afterwards, when a communication had been opened, 

 it fell to 86°." 



ft The temperature of the water in one of the shafts, which reached to 

 the lowest part of the mine, and from which it continually overflowed, was 

 52i°. 



XX The temperature of the water running through the adit, was 52°; 

 " as we approached the engine-shaft, it was increased to 53°." 



^(J In another shaft, the temperatures were precisely the same, at the 

 same depths. 



II II " The time allowed for the thermometer to remain at the different 

 depths (except the last) was ten minutes, which perhaps was scarcely long 

 enough." 



ll'This was the bottom of the mioe, where the thermometer was allowed 

 to remain for four hours. 



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