Two shafts, situated about ½ mile from Washington station, on the North-eastern railway, are being sunk on the dip side, and about 1 mile from Washington colliery. A preliminary borehole was made to the stone-head, and proved the following strata :—

Owing to the occurrence of water-bearing sands to a depth of 79 feet 5 inches, a modification of the Poetseh freezing-method of sinking has been adopted. The work is being carried out by Messrs. Gebhardt and Koenig of Nordhausen, Germany and it is the first attempt ever made to sink shafts by the freezing process in Great Britain.

The No. 1 pit was sunk in the ordinary way, with a diameter of 24 feet to a depth of 24 feet. At that point, twenty-two boreholes were bored in a circle 22½ feet in diameter, and temporarily lined with steel tubes, 6 inches in diameter. Afterwards, flush-jointed steel freezing-tubes, 110 feet long, 4 inches in diameter, and closed at the lower ends, were inserted in each bore-hole, and the temporary casing was removed. Smaller and central copper tubes, 1 inch in diameter, for conveying the brine, and perforated at the lower ends, were placed in side the freezing tubes. The tops of the small tubes are connected to an annular pipe, placed near the top of the shaft, and to the deli very-end of a small steam-driven pump, which forces the cooled brine down and through them. The tops of the large tubes are connected to an annular pipe and to the cisterns in which the brine is cooled, whence it is drawn by the brine-pump.

The freezing plant comprises a horizontal steam-engine, with a cylinder, 18 inches in diameter and 24 inches stroke, driving by belt and shafting two horizontal compressors, which deliver the ammonia a at a pressure of 150 pounds per square inch. The ammonia a passes, at this pressure, through 1,600 feet of 1 inch tube placed in two water-tanks or condensers, through which 4,000 gallons of cooled water circulate per hour, and is mechanically stirred by rotating paddles, and the ammonia becomes liquid. Immediately after leaving the condensers, the liquid ammonia passes thorough valves, where the ammonia is evaporated and the pressure is reduced to 14 pounds per square inch, produced by the exhausting action of the compressing-pump. At this reduced pressure, the gaseous ammonia passes along 2,000 feet of 1 inch tubes immersed in three cisterns or refrigerators, and then returns to the compressor. The refrigerators are filled with brine, which is mechanically stirred by rotating paddles, the solution containing from 21 per cent. in the early stage of the freezing to 26 per cent. of chloride of magnesium at the present time.

About 6 months were spent in erecting the plant and boring and preparing the bore-holes. Freezing commenced on March 23rd, 1902, with one compressor, and on April 1st, the second compressor was started. The temperature of the brine, at the commencement, varied from -8° to -11° Cent. on going to the shaft ; and in the return-tubes the temperature varied from -6½ to -9° Cent. On April 2nd, the temperature of the brine fell to -16° Cent. and has gradually fallen, until, at the present time, it is about -21° Cent. The brine returning from the shaft is generally about 2° Cent. warmer than when entering.

The strata were frozen to a radial distance of about 5 feet around each pipe ; but as the centre of the shaft was not frozen the quicksand was easily removed. The sinking at the No. 1 shaft through the frozen quicksand was commenced on May 5th, and completed on May 19th, and the shaft is being lined with brickworks set in cement, with an inner diameter of 14 feet. Ten men were employed in the sinking of the shaft through the frozen ground, by picks and wedges, in three shifts of 6 hours each, with 12 hour's rest, and the sinking proceeded continuously. This shaft will be sunk to a depth of about 720 feet by ordinary methods, to the Hutton seam.

At No. 2 shaft, boring operations are now proceeding for the purpose of making the bore-hole for the freezing-pipes.

Mr. A. L. Steavenson moved a hearty vote of thanks to the owners of Washington colliery for their kindness in allowing the members to see that very interesting freezing system at work. It was fifty years since he had signed his indentures as a mining- engineer, and yet he was still acquiring valuable information.

Mr. R. Donald Bain (H.M. Inspector of Mines) seconded the vote of thanks, which was cordially approved.