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ANNEXURE A. SUMMARY OF REPORTS BY INSPECTORS OF MINES. NORTHERN INSPECTION DISTRIOT (Mr. William Baeolay, Inspector). Tho total output of coal produoed from tho mines in the Northern Inspection District for the year 1927 was 747,530 tons, an increase of 93,081 tons when compared with, the returns of the previous yoar. Employment figures of miners in and about the coal-mines in the Northern District showed an average of 1,478 men for the year 1.927, an inercaso of 136 over the figures of tho previous year. With one or two exceptions, all the principal mines returned largor outputs owing to the fact that the Railway Department took increased supplies of local coal for locomotive use. Bord pillars and barriers havo beon substantially increased in sizo in all the mines, and the managers speak highly of the benefits now obtaining in pillar-extraction from tho formation of larger pillars in the first workings. Underground fires can bo better controlled within the limits of tho goaf, and more settled conditions prevail during the actual extraction of the pillars. In the Waikato district alone there are approximately 10,000,000 tons of coal standing on pillars—a quantity equal to seventeen years' output at the present rate of extraction. Much of the coal is liable to spontaneous combustion, especially where thore are tails, and the open workings are a menace to the safety of tho mines by reason of the fact that they provide reeessos for dust and gas accumulations. The problem in connection with the trcatmont of dangerous accumulations in old workings is being gradually overcome by scaling off tho disusod bord and heading roadway sections with brick stoppings at the entrances to the first workings, thus minimizing the risks attachable to gas and dust accumulations, and also preventing to a great extent, by the exclusion of oxygen, the self-heating of tho coal in abandoned workings. The practice of stono-d listing the accessible workings of tho mines, as a means of preventing fires and disastrous explosions, has been followed by tho managers of all the collieries in this district. In one colliery tho dust on 11,000 yards of roadways was sampled, tested, and treated. During- the year there has been considerable activity in mine-development and coal-prospecting. The Renown Colliery, formerly known as lletherington's Colliory, Waikokowai, is being equipped with modern machinery and developed to market its coal early in tho winter season. Several coal-prospecting liconsos have been granted in tho Tangarakau distriot, Taranaki, and operations to date have exposed a numbor of thin seams of brown coal accessible to tho railway by tramway connection. Hikurangi Goal Co., Ltd. (Shaft Colliery). —A noteworthy feature in connection with the operations of this mine for the past year is the remarkable recovery made both from a. mining and financial point of view. During the previous year the mine-workings were flooded for a period of five months, and the output in consequence was only 20,908 tons. For the past year the output was 87,005 tons, and tho overhead charges in connection with the operations of this large colliery would bo practically the same as tho previous year. During the year many additions to plant and buildings were made, notably a new electric generating unit and motor for a 9 in. pump, a main and tail-rope haulage plant for the west side, the extension of the surface endless-rope haulage system to connect with the loading-bank at the railway-sidings, a Keith and Rlackman ventilating-fan of a capacity of 50,000 cubic feet of air per minute, and an extension of tho bathhouse in order to provide additional bathing-accommodation for workmen. During the past six months the headings in McKenzie's dip section havo boon standing owing to the incidence of periodical water " bursts " from tho faults and to the inefficiency of the installed pumps. The headings of the western district have proved an area of 30 acres of workable coal of excellent quality, free from faults, and the seam is moderately inclined to the rise of the haulage system. All the working-places in the mine are systematically timbered with set supports to roof and covering laths. The dust on the roadways throughout the mino has been sampled and analysed, and the records of the results furnished evidence of naturally wet conditions. Several pillars in the west soction have been removed between two faults, and a crushing movement which settled on the small 30-ft.-square pillars was responsible for an increase in temperature to 80° wet and 81° dry in the return places. Pillars of 30 ft. square are totally inadequate in size for tho support of a roof aroa of 450 ft. at the point of extraction. Under the present management 50-ft.-square pillars havo been formed in the first workings to support the roof-cover where the workings are in close proximity to the base of the Hikurangi Mountain. Tho ventilation of the workings has boon remarkably improved during tho year, due to the largor fan and to the oxtension of the use of brick stoppings in crosscuts between intake and return. An average output of 400 tons per day has been maintained during the year. Wilson's Colliery, Hikurangi. —The main dip headings of the company's Waro Colliory have beon extended altogether one mile from the mine entrance, and have reached the boundary of the extensive Hikurangi Swamp. An inrush of water, estimated at 15,000 gallons per hour, caused the cessation of mining operations until such time as a more powerful pump could be obtained and installed at tho point of inflow. Much splitting of the seam by the occurrence of fireclay bands has boen encountered in the dip workings, and the workable thickness of coal has in oonsequence beon reduced to 5 ft. in the majority of the places. The pillars have been successfully extracted in the stone-drive soction, and the crushing movement has been confined to the limits of the goaf by the formation of larger pillars both in barriers and botween bords. Tho roadways are naturally wet throughout, with the exception of small stretches. Tho mine-dust has been sampled and tested on several occasions, and the results disclosed that the dust contained a large percentage of both moisture and ash. A marked decrease in tho average of temperature of the mine lias been recorded in all sections. Auxiliary fans havo been installed to ventilate the dip-developing places. A subsidiary cndless-ropo haulage plant, electrically driven, has beon installed to operate in the main dip and connect with the main haulage system. A new bathhouse, designed to provide twelve additional cabinets for showers has been constructed in concrete and is now in commission. Tho combined pumps are raising to the surface approximately 30,000 gallons of water per hour, and another steam boiler has boon installed on the surface for the purpose of augmenting tho supply of steam to the electric generators. Mino-development during the year has fallen short of supplying the usual number of places, due to the splitting of the scam and its displacement I>3' faults. Kerr and Co. (Phoenix Colliery). —Operations by tho co operative party during the year have been confined to tho removal of pillars in an area known locally as the Phunix section, to tho west of the Main North Road. This mine section was formerly worked by Moody and Co. about thirty years ago, and the workings at that time covored an area which has since beon acquired for the deviation of the Main North Road. Pillars of small dimensions, to a dopth of 30 ft. from the surface and to a distance of fully 20 chains along the line of road, were left in to support the road surface. None of the coal pillars under the road remaining from the previous working have been extracted by tho party. Kerr and Go. (Rocks Mine). —Two miners, by arrangement with Kerr and Co., wore engaged in working out sevoral abandoned coal pillars noar the outcrop, and 714 tons of coal was recovered by tho party. The output was convoyed by road to Hikurangi Railway-station, a distance of two miles. Silverdale Colliery (Foot's Grown Lease). — A new mine section conveniently situated to the County Road has been opened during the year. A coal-seam of 2 ft. 6 in. in thickness was reaehod at 70 ft. by a dip drive 1 in 3, and 2 ft. of fireclay is uplifted in tho main headings in order to provide passages for tho skips. A modified system of longwall working has been adopted to facilitate the extraction of the pillars, Large pillars are being formed in the