ENGINEERING. 



317 



The depth of the tunnel below the street surface at 

 the termini is such that elevators, or, as the English 

 more concisely call them, " lifts," are necessary at the 

 stations. There are three of these at each of the main 

 stations of the tunnel, each being a room 17x20 feet, 

 handsomely lined with hard woods, and supported by 

 framed iron floors. Each lift will carry 100 passengers 

 at a time. The lifting power is hydraulic, fed from a 

 large tank. 



The distance between the two water-side stations is 

 2,000 yards. The greatest depth of the tunnel-crown, 

 below average high- water mark in the Mersey, is 130 

 feet, of which 30 feet are below the river-bed. The 

 deepest elevator shaft is at the Hamilton Square station, 

 Birkenhead (87 feet 6 inches) ; that at James Street sta- 

 tion, Liverpool, is 76 feet 6 inches. In general profile 

 that part of the tunnel that underlies the river consists 

 of an incline from the Liverpool side of about 900 feet, 

 at a grade of 1 in 27 ; a mid-river section, nearly level, 

 but graded both ways for drainage, of 2,000 feet ; and 

 an incline of 1,760 feet on the Birkenhead side, at a 

 grade of 1 in 30. The steep inclines are continued in 

 both directions to connect with various stations in the 

 two cities. The tunnel proper has a width of 26 feet 

 and a height above rail of 19 feet. At the stations this 

 is increased to 56 feet 6 inches span, and 32 feet in 

 height, with ample platforms and provision for light and 

 air. 



The work was nominally begun soon after the enabling 

 act of Parliament in 1871, but it was not energetically 

 pushed until 1879. Since that time 3,000 men have been 

 kept constantly at work, and no death has occurred for 

 which the contractors have been held responsible. On 

 Jan. 17, 1884, the workmen from Lancashire and Cheshire 

 shook hands under the river-bed. 



The Beaumont boring-machine, which scoops out a 

 tunnel seven feet in diameter, was used for the prelimin- 

 ary headings throughout. 



Mr. James Brunlees and Mr. 0. Douglass Fox were 

 the engineers in charge of the entire work. 



The Severn Railway-Tunnel. Work was begun on this 

 tunnel in March, 1873, by the Great Western Company, 

 and, but for engineering difficulties of a character that 

 could not be foreseen, it would have been completed 

 long before the similar but far less formidable work on 

 the Mersey. It was opened for traffic September 1. At 

 Port Skewett the tidal estuary of the Severn is 2 miles 

 wide, and the mid-channel depth is 100 feet at high 

 water. The crown of the tunnel is carried 45 feet be- 

 low the river-bed. From the deepest point the tunnel 

 slopes upward at an incline of 1 in 100 toward the Eng- 

 lish terminus, and 1 in 90 toward the Welsh terminus. 

 The total length of actual tunnel is about 4 miles, and 

 at either end are deep cuttings 3,500 yards long. Drain- 

 age of more than 6 miles has to be provided for by 

 pumping power. The geological formation is mainly 

 marls, sandstones and shales with highly inclined coal 

 strata and a very difficult conglomerate of pebbles and 

 bowlders. In October, 1879, the original headings had 

 been carried to within 130 yards of junction under the 

 river when a large inflow of water, known as the "big 

 spring," took place on the headway on the Welsh side of 

 the river and filled the works. Simultaneously the wells 

 in the neighborhood ceased to flow, and the river Nedern 

 ran dry. The pumps were of course unable to deal with 

 such a volume of water, and a diver named Lambert 



