BY W.AI. FKYAK, INSPECTOR OF MIXES, QUEENSLAND. -lo 



character, so far as coal mining is concerned, do not to any 

 g''eat extent affect our more important division of that industry. 

 In the other case it is extremely probable that effective 

 ventilation would have had a very beneficial influence in 

 modifying, if not entirely obviating, the great increase above 

 the normal temperature, as the district in question had not 

 acquired much reputation for progress in that direction at the 

 time at which the "observations " were taken. The observations I 

 have been privileged to take at Gympie, with my remarks 

 thereon, will show that there is reason to believe that the above 

 theory does not apply on that field at any rate. And they afford 

 evidence that so far as our present depths are concerned— that is, 

 at or under 1,500 feet — there need be no material increment of 

 temperature above that of the normal temperature of the 

 invariable plane, and which would at the worst be much lower 

 than the temperature at the surface in summer. 



The observations taken at Gympie have not been taken in 

 holes drilled into the rock, nor in the water issuing from the 

 rock, as has been customary when the information has 

 been sought for philosophical reasoning rather than for 

 practical purposes, but have been taken in the air of the 

 mine where it has full play, and is such as men would ordinarily 

 breathe at the depths mentioned. The temperature of the Avater 

 issuing from the rocks must be a very uncertain means of 

 estimating the temperature of the mine for practical purposes, 

 as the source of supply may be far distant and the depth of 

 some portion of its course far below the level at which its 

 temperature is taken ; and when water in a tepid state issues it 

 cannot at once raise the temperature of a mine to its own heat, 

 but must itself proportionally lose a portion of heat. 



The first set of observations at Gympie was taken on 14th 

 and loth December, 1K8S, when our semi-tropical heat is 

 nearing its maximum. But the four hottest hours (11 to 3) 

 were avoided, and tlie surface temperature taken in the shadiest 

 place at the surface of the mine. The temperature had been 

 high during the preceding week, 102 degs. to 106 degs. on the 

 verandahs of the houses near. The Inglewood mine is not 

 connected with anv other but is centred to the bottom — that is. 



