Show limit of de depoli lie belo 60 50 ft A the temperature ture rises in the proportion of one degree decree for e very every 6 65 5 ft of derith depth except pep where currents of water carry carte y the uh heat away a why the result is that at a depth of ft we reach a a temperature ture of a bout 98 I 1 degrees or blood heat this renders it exceedingly p difficult to work coal pits below that abat depth this is is the reason gt britaina Brit ains coal commission haade has de aided abl that t mines miner s are unworkable biblo f fa r the thickness thick hess ess of the solid rock bull building ding up the crust of theeart the earth is at 16 least ast 30 or 40 miles in ties at that thai dep depth th the heat beat is would tia ti A reduce eve the earthie surta cri ah aqui quid id but ut the pressure of ahe the X 0 overlying er lying rocks is is so tp great that until the relation of the he heat beat to the pressure is is known it cannot be said wt hether t he earth at that depth is fluid or solid |