316 PROCEEDINGS OF SECTION C. 
covered board, and all fit into a box about 2 feet 6 inches 
long by 1 foot wide and 8 inches high. 
One of Compton’s reflecting galvanometers with coil on a 
bifilar suspension was used, but this was far better than is 
needed. ; 
The following results have been obtained :—At the South ~ 
‘German Mine, Maldon, at a depth 1700 feet. The test was 
made in a heading that had been driven two months pre- 
viously, but through which no current of air, save that from 
the rock-drill, had passed. The rock temperature was 
81° Fahr., and, on the assumption that the mean sur- 
face temperature is 60° Fahr., the rise is equivalent to 1° 
Fahr. per 81 feet, or 1° Centigrade per 145 feet. At Bal- 
larat, at the Band and Albion Mine, depth 2080 feet, and — 
conditions as at Maldon, the rock temperature was 86° 
Fahr., and, on the same assumption as before, this is equiva- 
lent to a rise of 1° Fahr. in 80 feet, or 1° Centigrade in 144 
feet. These two tests must be considered preliminary ones, 
the mean temperature of the surface, at least at Ballarat, is 
probably lower than stated, and opportunity is being awaited 
for some new bore or shaft in new ground by which to 
obtain the figure more accurately. 
The more exact work, so far, has been done at Bendigo, 
and at the “ North Garden Gully, Carlisle, and Passby ” 
Mine, at a depth of 3000 feet, under very good con- 
ditions, the temperature was found to be 99° Fahr. by a de- 
layed thermometer, reading only to -5°, and 99:1° Fahr. by 
the, resistance-thermometer and adjustable bridge. This, 
on the same assumption as before as to mean surface tem- 
perature, is equivalent to 1° Fahr. in 77 feet, or 19 Centi- 
grade in 138 feet. At the “New Chum Railway” Mine, 
also at Bendigo, several readings have been taken at a depth 
of 3645 feet. The first wasat the foot of a winze sunk at the 
full rate of progress for the last 400 feet, and the second one at 
the end of a short drive from the bottom of this winze. The 
temperature found by the aid of the resistance-thermometer 
and the new form of bridge both gave 106:95° Fahr., and, 
under the assumption as before as to the surface temperature, 
this corresponds to a rate of 1° Fahr. in 77-5 feet, or 1° 
Centigrade in 139 feet. It has been difficult to find a suit- 
able shallow shaft near to these mines, by which to obtain 
the mean surface temperature, but at the Don Mine, about 
two miles away, the temperature at a depth of 182 feet was 
found to be 63-7° Fahr., whilst at the Government shaft at 
Ellesmere, at a depth of 247 feet, the temperature was found 
to be 64:9° Fahr. Both readings were by the delayed type 
