27

C—2

With a view of ascertaining to what extent the conditions existing in hot and humid working-places may be improved by the circulation of air at increased, velocity, a number of observations have been recently taken by some mining engineers, consisting of Messrs. M. Paul, Inspector of Mines ; A. H. V. Morgan, Director of Waihi (School of Mines; E. G. Banks, superintendent, and J. L. Gilmour, manager, of the Waihi Gold-mine; W. McOonachie, manager of the Waihi Grand Junction Gold-mine; and by myself. The observations were principally taken for the purpose of establishing, if possible, a katathermometer standard for warm mines as an improvement on the existing wet-bulb-ther ometer stan !ard. The places of observations were specially chosen where the velocity of the air for experimental purposes could be regulated and increased when desired, and do not always represent the working-conditions of the mines. Upon reference to the tabulation of the results thus obtained it will be seen how rapidly the cooling-power, as indicated by katathermometer, improved with increased air-velocity, as shown by observations Nos. 2 and 3, being one series taken at the same point; Nos. 4, 5, and 6, a series taken at one point; and Nos. 11 and 12, another series at one point, increasing through each series the velocities from still air. The opinions expressed on the physiological conditions contained in the last column were conscientiously arrived at by the mining engineers, who base their opinions upon what they believed to be the conditions existing ; but when compared with the standard of the inventor of the katathermometer, Dr. Hill (viz., that for sedentary workers the dry katathermometer should be kept not less than 6 and the wet 16-5, but that the cooling-power should be higher than these for severir forms of mechanical work), the standard here adopted by the New Zealand engineers (viz., 4-04 dry katathermometer and 10-6 wet katathermometer) are much less exacting, .and, not being subject to medical analysis, cannot claim equal authority to Dr. Hill's standard. Thus, for the present, insufficient evidence exists by which to determine a legal katathermometer standard for mines. The observations, however, arc of considerable value in showing the benefit of moving air at the working-places; likewise, observation No. 13, taken in still air in the warmest place in the warmest colliery in the North Island, provides satisfactory evidence that the temperature of our coal-mines is not excessive.

Tabulated Results of Observations taken to ascertain the Physiological Conditions at some Mines in New Zealand.

Notes. The instruments used consisted of Professor Hill's katathcrmomoter, Biram- Davis anemometer, nnd Sling hygrometer. Standard of Professor Leonard Hill, F.R.S., the inventor of the katathermometer : For sedentary workers the dry katathcrmometer should be kept not less than 6, and the wet 16£. The cooling-power should be higher for severer forms of mechanical work. In the above tabulation the mining engineers have taken a lower standard—viz., not less than 4 dry bulb and 10-6 wot bulb. At the Waihi Goldlield the rate of increment of the temperature of the rocks with depth is approximately I F. in 33 ft., thus great difficulty exists in keeping the workings in a satisfactory condition.

S O © u v • ll Place of Observation. Out. Tempt in SI door Stature hade. Katathermo- — «r m PotiS 5§ .it i lace. calorics per Sqr. t£ cm.p. Sec. o £ - ** Physiological Conditions as believed by the Mining ICngincers present at the Tests. Date. Wet Bulb. Dry Bulb. Wet Bulb. Dry Bulb. Wet "Dry Bulb. Bulb. 5 - \> Seatoun, Wellington (hills) °F. 18/1/22 56-60 °F. 65-00 °F. 56-60 °F. 65-00 57-60 24-90 14-30 Salubrious conditions for arduous physical work. 2 Waihi Gold-mine— No. 13 (1,450 ft.) level, Martha lode west No. 13 (1,450 ft.) level 28/1/22 61-50 02-30 80-25 81-40 9-40 2-90 Still air 12-90 Oppressive. 3 4 5 Royal lode west 28/1/22 61-50 30/1/22 59-00 30/1/22 59-00 59-00 62-30 64-00 64-00 78-60 88-00 84-70 80-20 88-70 88-00 33-20 4-90 21-80 15-00 1-57 4-46 Still air 6-00 Velocity of air excessive for continual physical work. Extremely oppressive conditions and unendurable, inducing profuse perspiration on unclothed men resting. Velocity of air rendered conditions satisfactory for physical work. Velocity of air excessive. Lower limit of satisfactory conditions, velocity just sufficient to deflect candle-flame. Satisfactory stoping conditions. 6 7 900 ft. "level, Edward lode, White's stope 30/1/22 59-00 14/3/22 58-00 59-00 58-00 64-00 67-50 83-00 78-00 87-00 79-50 27-10 11-10 6-30 4-04 11-85 0-70 8 1,150 ft. level, Edward lode, Heath's stope 1,205 ft. level, Edward lode, Harrison's stope Edward lode, Salmon crosscut Waihi Grand Junction Gold-mine, No. 7 (1,200 ft. level), southeast cross-cut to Empire lode Ditto 14/3/22 58-00 58-00 67-50 76-50 77-50 12-40 5-04 0-54 9 10 14/3/22 58-00 58-00 58-00 67-50 67-50 77-00 79-00 77-50 81-00 10-60 24-20 4-07 11-30 0-42 12-60 Lower limit of satisfactory conditions. Satisfactory conditions. 14/3/22 58-00 11 31/1/22 62-50 62-50 67-00 76-00 77-00 11-70 4-42 0-65 Considered reasonable workingconditions for naturally hot mines. 31/1/22 62-50 Good conditions for working in naturally hot mines. Fair conditions. Of the two miners working only one had his shirt off. Considered to be the warmest place in the colliery : if so, colliery-workings on the Waikato coalfield are reasonably cool. 12 62-50 67-00 72-00 74-50 19-20 8-30 .1-83 13 Taupiri Extended Colliery, No. 1 west dip heading, 300 ft. deep 6/2/22 j 64-00 64-00 78-00 04-50 66-70 17-01 6-21 Still air