45

C—4

No. 4.—Air-measurements taken at Waihi Grand Junction Mine, 28th August, 1911.

Note. —The fan is of Sirocco type, double inlet, 19 in. diameter, electrically driven: estimated 8.H.P., 34; observed W.G., M 2 in. at fan. Wet Bulb. Dry Bulb. Temperature of outside air in shade ... . ... 51|° 54° mine-air discharged by fan ... ... 69° .69° maximum observed ... ... 83° 83J° minimum observed ... ... 64i° 70|°

(Ventilated by Sirocco fan.) Quantity of Air j Total Number of Average Quantity Locality where Measurements taken. circulating per Men on of Air per Man Minute. Day Shift. per Minute. ~ ~ ~ ~~" " 1 T "~~ ~ Intake Air. No. 5 level (944 ft. deep) — Gub. ft. Cub. ft. South crosscut .. .. .. .. ! 16,293 50 325 North crosscut .. .. .. .. 14,492 12 1,208 No. 4 level (794 ft. deep)--North crosscut .. .. .. .. 1.738 18 263 No. 3 levelNorth crosscut .. .. . . .. 9,332 8 1,166 I j Quantity descending main shaft .. 44,855 other inlets .. .. 2,710 44,855 2,710 Total intake .. .. .. 47,565 47,565 Return Air. Returning via Extended Mine at No. 5 level . . 11,550 Returning through Sirocco fan .. .. 36,015 11,550 36,015 Total measured return .. . . 47,565 88 540 47,565 47,565 88 540