Page:Transactions of the Provincial Medical and Surgical Association, volume 2.djvu/124

the temperature is found to increase about one degree of Farenheit for every 50 or 60 feet that we descend. The following table. constructed from my journals of many painful visits to some of the Cornish mines, gives, at one view, the temperature of the air and water^[1] of six mines of this district; and the mean of the whole, given in the last column, may be considered as a correct statement of the temperature of the subterranean climate of the miner, at the various depths at which he works.

Mean Results of the Temperature of Six Mines.
Depth in Feet.			Huel Neptune.		Botul-lack		Little Bounds.		Ding Dong		Hul Vor.		Dolcoath.		Mean.
			A.	W.	A.	W.	A.	W.	A.	W.	A.	W.	A.	W.	A.	W.
120	to	150	57		59	57			55						57	57
150		200		60	58	54	54								57	56
200		250	56		61		57	55			69	57			58	56
250		300	56	55	61	59	57	59					60		58	58
300		350	58	54			55	55							57	55
350		400		57	66	62			55						60	59
400		450	60		66				56	54					61	54
450		500							60	55					61	54
500		550	67	67	67	68					61	60	64		65	65
550		600							62	63	61	63			63	63
600		650							62	63	61	63			62	63
650		700							64	64	65	64			65	64
700		750									67	65			67	65
750		800									68	68			66	66
800		850									66	66			66	66
850		900										68				68
900		950										71	62		[2]62	71
950		1150											70	66	70	66
1150		1260											71	71	71	71
1260		1350											76	74	76	74
1350		1400											83	79	83	79

Ventilation.─The existence of this temperature at the bottom of mines, (however produced) will, of itself, necessarily occasion a constant circulation of air upwards, through the shafts; and as what ascends must be replaced by the air above, there will, of

1. Marked, respectively, in the Table, A. and W.
2. Here there was a strong current of air.