In the wake of the small heading gallery came the other gangs. These rigged up the timber and other supports to the roof and excavated the small opening to the full dimensions of the tunnel. Last of all came the masons, setting the masonry lining, from 18 to 30 inches thick, in position, for the tunnel is lined throughout. In passing through the granite rock there was but little fear of a collapse of the roof, but in the treacherous clay advance had to be made warily, and heavy timbering resorted to, in order to prevent the soft soil caving in and burying all in its sticky embrace. The material for the headings and lining, as well as the workmen and tools, were carried to and fro upon a small railway, the locomotives of which were driven by compressed air--steam was impracticable, because it would have fouled the workings; while on the short distance between the inner end of the railway and the working face haulage was done by horses. The privations suffered by the navvies was only equalled by those experienced by the animals, the mortality of which ran up to as high as twenty-five per cent. of the number employed. Water was a constant menace, and at times retarded progress seriously. On the south side it was particularly troublesome. Time after time the drills or detonating charges would tap one of these subterranean streams, and the water would pour out in a cascade. These rivulets were of varying volume, but in one stretch, where the rock was extremely friable, it was considered too dangerous to use the mechanical drilling machine, so the men had to cut their way forward by hand. In so doing they released a vast underground pocket of water, which rushed out at the rate of over 3000 gallons per minute. At one spot it was only by superhuman effort that headway was made, for the men were half submerged in these torrential outbursts, escape from which was only possible by penetrating farther into the mountain. In 1876 another terrible calamity overtook Louis Favre. It was discovered suddenly that the railway, far from costing the estimated sum, would approximate over £11,500,000, or $57,500,000. Somebody had blundered, and badly too. A deficit of over £4,000,000, or $20,000,000, appeared certain. What was to be done? The development of such a contingency never could have happened at a more inopportune moment. Times were hard; money was scarce; financial crashes loomed in every quarter of the Continent; and, to make matters worse, war was raging. Never in the history of engineering had such an extraordinary and unaccountable mistake been made in the estimates.