His work on this road became one of the important elements of the success, and one of the great causes of the distinction, which marked the life of these rising engineers. The successful construction of that part of the line which lay across "Chat Moss," an unfathomable swampy deposit of peat, extending over an area of 12 square miles, and the building of which had been repeatedly declared an impossibility, was in itself sufficient to prove that the engineer who had accomplished it was no common man. Stephenson adopted the very simple yet bold expedient of using, as a filling, compacted turf and peat, and building a road-bed of materials lighter than water, or the substance composing the bog, and thus forming a _floating_ embankment, on which he laid his rails. To the surprise of every one but Stephenson himself, the plan proved perfectly successful, and even surprisingly economical, costing but little more than one-tenth the estimate of at least one engineer. Among the other great works on this remarkable pioneer-line were the tunnel, a mile and a half long, from the station at Liverpool to Edgehill; the Olive Mount deep-cut, two miles long, and in some places 100 feet deep, through red sandstone, of which nearly 500,000 yards were removed; the Sankey Viaduct, a brick structure of nine arches, of 50 feet span each, costing £45,000; and a number of other pieces of work which are noteworthy in even these days of great works. Stephenson planned all details of the line, and even designed the bridges, machinery, engines, turn-tables, switches, and crossings, and was responsible for every part of the work of their construction.