5A REPORT—1904. 
In South Wales, in the neighbourhood of Rhondda and Aberdare, 
Mr. William Jenkins has taken numerous observations by a somewhat 
rough method, an ordinary thermometer being inserted in a hole bored 
3 feet deep into the coal, with an oiled waste plugging, and taken out 
from time to time and reinserted till the temperature was steady, the 
whole time being upwards of an hour. The observations were made in 
various seams at depths below the surface ranging from 1,094 feet to 
2,515 feet, with very varying results, the surface being 875 feet above 
sea-level. Taking the surface temperature as 47°, and comparing it with 
the deepest observation (735° at 2,515 feet), we have an increase of 
264° in 2,515 feet, which is at the rate of 1° in 95 feet ; but the mode of 
observation is unsatisfactory. 
At Dowlais, in the Merthyr coalfield, Mr. H. W. Martin has taken 
numerous observations in several collieries by means of thermometers 
inserted in boreholes and left for about twenty-four hours, the instruments 
being apparently strong thermometers specially ordered from a local 
optician. The greatest depth below the surface was 2,600 feet, with 
temperature 77°. Assuming the surface temperature to be 49°, this gives 
a rate of 1° in 93 feet. The inclination of the strata averages about 1 in 7. 
At the Niddrie Collieries, near Edinburgh, Mr. Robert Martin has 
made observations in the Great Seam at the depth of 2,623 feet, and finds 
the ‘temperature in the solid coal face’ at this depth to be 74°. The 
surface ground temperatures found at four surrounding stations of the 
Scottish Meteorological Society (Joppa, Nookton, East Linton, Smeaton) 
are 46°1, 47°°6, 47°°7, 47°-9. Assuming a surface temperature of 47°°5, 
we have an increase at the rate of 1° in 99 feet. The strata are highly 
inclined, the dip ranging from 50° to 90° ; a circumstance conducive to a 
slow rate of increase. 
Hofrat Prof. H. Hofer, of Leoben, Austria, has recently issued, with 
the sanction of the Austrian mining authorities, a circular giving direc- 
tions for the taking of temperature observations during the sinking of 
mining shafts, and has since been furnished, at his own request, with 
copies of most of the reports of your Committee. The circular recom- 
mends the use of maximum thermometers, divided to fifths of a degree 
centigrade, to be inserted in holes bored to the depth of at least 2 metres 
in the floor or side and well plugged. The observations are to begin at 
25m. from the surface, to be repeated at intervals of 50 m. till a coal 
seam is approached, and then at shorter intervals through and a little 
beyond the seam. This process is to be repeated for every seam that is 
traversed. A main purpose of the investigation! is to determine the 
influence of coal seams on the temperature of their surroundings. Hot 
springs have been encountered in several Austrian coal mines, and Pro- 
fessor Hofer ascribes their heat to chemical changes in the coal. In this 
connection it may be mentioned that much evidence has come before the 
Coal Commission of spontaneous heating of coal by exposure to the air. 
According to Professor Hifer the greatest heating occurs in brown coal. 
It seems desirable at this time to make more generally known to 
observers of rock temperature in mines that the simple and strong pattern 
of slow-action thermometer, designed by your Committee many years ago 
for this purpose, is still obtainable from the makers, Messrs. Negretti & 
1 Oester. Zeitschrift fiir Berg- wnd Hiittennesen, 1901, p. 249, &c. Also paper to 
Institution of Mining Engineers, London Conference, 1904. 
