abe PROCEEDINGS OF SECTION C. 
namely, by the approach to the spot by means of a mine 
drive. Some figures have already been published by Mr. 
J. Sterling* for the temperatures met with in “ Lansell’s 
180”’ Gold Mine, Bendigo, showing that there was at a 
depth of— 
454 feet a rise of 1° Fahrenheit im 110 feet 
1294>-;; Fe 19° be in: £32" "s, 
1750 _,; ¥ 1° % Mm LTS", 
2290: "5, 1° “ m5 20 
2101 © ;, ‘5 {2 : In Sie os 
S110... ,3 f 1° , mh 's 
3250 ,, 3 1° Es nS. 
and an everage for the whole distance of 19 Fahrenheit for 
every 135 feet, or a rise in temperature of 1° Cenugrade 
per 243 feet. But it did not appear that the proper pre- 
cautions had been taken to secure the experiments against 
serious sources of error; and the hopeless difficulty that the 
author met in trying to reconcile this abnormally small rate 
with the temperatures actually met with in the neighbouring 
mines was one cause for the present piece of work to be 
undertaken. 
It must be remembered that old mine-drives or shafts are 
always more or less cooled by circulating air or water, and 
hence cannot be at once utilised for the necessary measure- 
ments. The mines in the Bendigo saddlereefs present 
rather an extreme case for this rule, and a few readings that 
the author took near old workings were sufficient to show 
how great was the interference of the latter. It might be 
convenient to here state the conditions under which the tem- 
perature readings should be taken in the case of a mine. 
lst. The reading must be made in “new” ground, that 
is to say, away from all other workings, particularly deeper 
ones, and in a heading or a sinking quite recently and 
rapidly driven, so that its walls have not been unduly cooled 
by the ventilating current of air. 
2nd. The rock must be free from minerals that are easily 
oxidised. The reactions that take place between minerals 
and water and air are eothermic, and would seriously affect 
a reading if appreciable action were taking place. For- 
tunately, the rocks of a deep mine are usually dense ones ; 
but in the case of some loose ground containing marcasite, 
and that was being worked for gold, the author once noticed 
a rise in temperature at that spot of 15° C. over what was 
* Australasian Institute Mining Engineers, 1898, p. 94. 
