C.—2

and it is said that at the same time the mine was making more water than usual. Before the breakdown had been repaired and the pumps working normally the water had risen sufficiently to drown part of the plant. The water continued to rise till it reached a point 150 ft. up the shaft, and then leaked through the barrier into Wilson's Colliery. A large electric sinking-pump was installed by November, and the mine was unwatered early in January. This is the third time this mine has been flooded, and on each occasion the loss has been serious. Arrangements are now in hand to improve the efficiency and capacity of the pumping-plant and provide water standage so as to secure the mine against any future flooding. (e) Electricity at Collieries. (Regulation 243.) The following is a summary of the annual returns, in accordance with Regulation 243 (c), regarding electrical apparatus at collieries : — Number of collieries at which electrical apparatus is installed .. .. 45 Number of continuous-current installations .. .. . . .. 11 Number of alternating-current installations .. . . . . . . 35 Number of collieries electrically lighted . . . . . . . . 35 Number of collieries using electrical ventilating-machines . . 37 Number of collieries using electrical pumping plants . . . . . . 29 Number of collieries using electrical haulage plants . . . . . . 33 Number of collieries using electrical screening plants . . . . . . 14 Number of collieries using electrical miscellaneous plants . . . . 22 Number of collieries using electrical locomotives . . .. .. 1 Total horse-power employed from motors on surface .. .. .. 6,191 Total horse-power employed from motors below ground .. . . 3,894J (/) Prosecutions. Forty-one informations were laid by the District Inspectors during the year for breaches of the Coal-mines Act and Regulations ; one information was dismissed, three were withdrawn, and thirtyseven convictions were obtained. Accounts of the individual prosecutions are given in the reports of the District Inspectors (Annexure A).

SECTION Y.—LEGISLATION AFFECTING COAL-MINES. There were no amendments to the Coal-mines Act or to the Regulations during the year.

I desire again to acknowledge the efficient help and co-operation which I have received from the District Inspectors of Coal-mines. The ventilation of mines is always a subject of concern, particularly the ventilation of the gassy mines in the Grey district. It appears to the Inspectors and myself that too much reliance is placed on brattice-cloth, that much more use should be made of airsplitting, and that the use of brattice doors on haulage roads and jigs should, be avoided wherever practicable. Brattice has a short life, and requires constant repairs and frequent renewals, with the result that the cost of bratticing is quite a considerable item on most mine-cost sheets. One fact to which sufficient weight is rarely given is that when brattice is erected along a roadway, 2 ft. to 3 ft. from the side of the pillar as is commonly the case, the ventilating-pressure required to drive a given air-current along behind 1 chain length of that brattice is as great as the pressure required to drive the same current of air along 50 to 100 chains of ordinary airway. It has often been stated that there is a limit to the number of splits into which the ventilating current of a mine can be divided with efficiency, and it is usually assumed that the efficient limit is soon reached. A study of the question as regards New Zealand mines proves conclusively that no mine has in any way approached the limit of efficiency as regards splitting. In a few mines the number of splits has recently been increased, and the result has always been better ventilation, better control of the air, and reduced consumption of power at the fan. In our mines the best results as regards cost are got with small sections; if gas in quantity has to be dealt with, or if the seam is liable to spontaneous combustion, there is a very strong case for making each such section a separate split. Where this practice has been followed it has been found that, besides the improvement in the ventilation, the trucking and haulage cost is reduced by reason of the fact that fewer brattice or wooden doors are required and also that the cost of air-crossings is more than balanced by the reduced cost of bratticing. I have, &c., J. A. C. Bayne, Inspecting Engineer and Chief Inspector of Coal-mines.

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