Page:Walker (1888) The Severn Tunnel.djvu/88

Rh only, and after the headings had been lowered, to put in the invert and underpin up to the arch. This was carried out through more than a mile of the work, and everywhere successfully.

The new winding-pit at Sudbrook was commenced on the 11th February, and was sunk to a depth of 30 feet by the 8th March. The shaft was 21 feet in diameter outside the brickwork, and 18 feet inside. It was impossible to sink this shaft more than 40 feet till the water was pumped out of the adjoining works. A bore-hole was started on the 20th April to allow the water to drain out of the pit into the heading below, when the new pumping-plant should have cleared the other works of water.

The two new pits at 5 miles 4 chains, known as pumping and winding shafts, were commenced on the 23rd February; and on the same day a long culvert, to convey the water out to the edge of the river, was also commenced. These two shafts reached a depth of 30 feet on the 8th March. On the 2ist April the winding-pit was 63 feet deep, and the pumping-pit 65 feet. On the 2nd June the winding-pit reached a bed of very hard conglomerate rock at a depth of 96 feet. This rock, which was known to exist, and had been found in the Sudbrook Pit at nearly the same level, had been nowhere met with in a greater thickness than 9 feet, and in many places it was known to be only 3 feet thick. In this unfortunate shaft the thickness proved to be 26 feet. The rock was very jointy, and full of