CHAP. XI.] STEPHENSON AGAIN APPOINTED ENGINEER. 281

CHAPTER XI.

CHAT MOSS-CONSTRUCTION OF THE RAILWAY.

THE appointment of principal engineer of the railway was taken into consideration at the first meeting of the directors held at Liverpool subsequent to the passing of the act of incorporation. The magnitude of the proposed works, and the vast consequences involved in the experiment, were deeply impressed on their minds, and they resolved to secure the services of a resident engineer of proved experience and ability. Their attention was naturally directed to George Stephenson; at the same time, they desired to have the benefit of the Messrs. Rennie's professional assistance in superintending the works. Mr. George Rennie had an interview with the board on the subject, at which he proposed to undertake the chief superintendence, making six visits in each year, and stipulating that he should have the appointment of the resident engineer. But the responsibility attaching to the direction in the matter of the efficient carrying on of the works would not admit of their being influenced by ordinary punctilios on the occasion, and they accordingly declined Mr. Rennie's proposal, and proceeded to appoint George Stephenson principal engineer at a salary of £1000 per annum.

He at once removed his residence to Liverpool, and made arrangements to commence the works. He began with the "impossible thing"-to do that which some of the principal engineers of the day had declared that "no man in his senses would undertake to do”—namely, to make the road over Chat Moss! It was, indeed, a most formidable undertaking, and the project of carrying a railway along, under, or over such a material as that of which it consisted would certainly never have occurred to an ordinary mind. Michael Drayton supposed the Moss to have had its origin at the Deluge. Nothing more impassable could have been imagined than that dreary waste; and Mr. Giles only spoke the popular feeling of the day when he declared that

no carriage could stand on it "short of the bottom." In this bog, singular to say, Mr. Roscoe, the accomplished historian of the Medicis, buried his fortune in the hopeless attempt to cultivate a portion of it which he had bought.

Chat Moss is an immense peat-bog of about twelve square miles in extent. Unlike the bogs or swamps of Cambridge and Lincolnshire, which consist principally of soft mud or silt, this bog is a vast mass of spongy vegetable pulp, the result of the growth and decay of ages. Spagni, or bog-mosses, cover the entire area; one year's growth rising over another, the older growths not entirely decaying, but remaining partially preserved by the antiseptic properties peculiar to peat. Hence the remarkable fact that, though a semifluid mass, the surface of Chat Moss rises above the level of the surrounding country. Like a turtle's back, it declines from the summit in every direction, having from thirty to forty feet gradual slope to the solid land on all sides. From the remains of trees, chiefly alder and birch, which have been dug out of it, and which must have previously flourished on the surface of the soil now deeply submerged, it is probable that the sand and clay base on which the bog rests is saucer-shaped, and so retains the entire mass in position. In rainy weather, such is its capacity for water that it sensibly swells, and rises in those parts where the moss is the deepest. This occurs through the capillary attraction of the fibres of the submerged moss, which is from twenty to thirty feet in depth, while the growing plants effectually check evaporation from the surface. This peculiar character of the Moss has presented an insuperable difficulty in the way of draining on any extensive system-such as by sinking shafts in its substance, and pumping up the water by steam-power, as has been proposed by some engineers. For, supposing a shaft of thirty feet deep to be sunk, it has been calculated that this would only be effectual for draining a circle of about one hundred yards, the water running down an incline of about 5 to 1; indeed, it was found, in the course of draining the bog, that a ditch three feet deep only served to drain a space of less than five yards on either side, and two ditches of this depth, ten feet apart, left a portion of the Moss between them scarcely affected by the drains.

The three resident engineers selected by Mr. Stephenson to su

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CHAP. XI.] THE RESIDENT ENGINEERS.-A MUD BATH. 283

perintend the construction of the line were Mr. Joseph Locke, Mr. Allcard, and Mr. John Dixon. The last was appointed to that portion which included the proposed road across the Moss, the other two being any thing but desirous of exchanging posts with him. On Mr. Dixon's arrival, about the month of July, 1826, Mr. Locke proceeded to show him over the length he was to take charge of, and to instal him in office. When they reached Chat Moss, Mr. Dixon found that the line had already been staked out and the levels taken in detail by the aid of planks laid upon the bog. The cutting of the drains along each side of the proposed road had also been commenced, but the soft pulpy stuff had up to this time flowed into the drains and filled them up as fast as they were cut. Proceeding across the Moss on his first day's inspection, the new resident, when about half way over, slipped off the plank on which he walked, and sank to his knees. in the bog. Struggling only sent him the deeper, and he might have disappeared altogether but for the workmen, who hastened to his assistance upon planks, and rescued him from his perilous position. Much disheartened, he desired to return, and even for the moment thought of giving up the job; but Mr. Locke assured him that the worst part was now past; so the new resident plucked up heart again, and both floundered on until they reached the farther edge of the Moss, wet and plastered over with bog sludge. Mr. Dixon's assistants endeavored to comfort him by the assurance that he might in future avoid similar perils by walking upon "pattens," or boards fastened to the soles of his feet, as they had done when taking the levels, and as the workmen did when engaged in making drains in the softest parts of the Moss. Still the resident engineer could not help being puzzled by the problem of how to construct a road for a heavy locomotive, with a train of passengers or goods, upon a bog which he had found to be incapable of supporting his own individual weight!

Stephenson's idea was that such a road might be made to float upon the bog simply by means of a sufficient extension of the bearing surface. As a ship, or a raft capable of sustaining heavy loads, floated in water, so, in his opinion, might a light road be floated upon a bog which was of considerably greater consistency than water. Long before the railway was thought of, Mr. Roscoe had adopted the remarkable expedient of fitting his plow-horses

with flat wooden soles or pattens, to enable them to walk upon the Moss land which he had brought into cultivation. These pattens were fitted on by means of a screw apparatus, which met in front of the foot and was easily fastened. The mode by which these pattens served to sustain the horse is capable of easy explanation, and it will be observed that the rationale alike explains the floating of a railway. The foot of an ordinary farmhorse presents a base of about five inches diameter, but if this base be enlarged to seven inches-the circles being to each other as the squares of the diameters-it will be found that, by this slight enlargement of the base, a circle of nearly double the area has been secured, and consequently the pressure of the foot upon every unit of ground on which the horse stands has been reduced one half. In fact, this contrivance has an effect tantamount to setting the horse upon eight feet instead of four.

Apply the same reasoning to the ponderous locomotive, and it will be found that even such a machine may be made to stand upon a bog by means of a similar extension of the bearing surface. Suppose the engine to be twenty feet long and five feet wide, thus covering a surface of a hundred square feet, and, provided the bearing has been extended by means of cross sleepers supported upon a matting of heath and branches of trees covered with a few inches of gravel, the pressure of an engine of twenty tons will be only equal to about three pounds per inch over the whole surface on which it stands. Such was George Stephenson's idea in contriving his floating road-something like an elongated raft-across the Moss; and we shall see that he steadily kept it in view in carrying the work into execution.

The first thing done was to form a footpath of ling or heather along the proposed road, on which a man might walk without risk of sinking. A single line of temporary railway was then laid down, formed of ordinary cross-bars about three feet long and an inch square, with holes punched through them at the end and nailed down to temporary sleepers. Along this way ran the wagons in which were conveyed the materials requisite to form the permanent road. These wagons carried about a ton each, and they were propelled by boys running behind them along the narrow bar of iron. The boys became so expert that they would run the four miles across at the rate of seven or eight miles an hour

CHAP. XI.]

FORMATION OF THE ROAD.

285

without missing a step; if they had done so, they would have sunk in many places up to their middle.* The slight extension of the bearing surface was sufficient to enable the bog to bear this temporary line, and the circumstance was a source of increased confidence and hope to our engineer in proceeding with the formation of the permanent road alongside.

The digging of drains had been proceeding for some time along each side of the intended railway, but they filled up almost as soon as dug, the sides flowing in and the bottom rising up, and it was only in some of the drier parts of the bog that a depth of three or four feet could be reached. The surface-ground between the drains, containing the intertwined roots of heather and long grass, was left untouched, and upon this were spread branches of trees and hedge-cuttings; in the softest places rude gates or hurdles, some eight or nine feet long by four feet wide, interwoven with heather, were laid in double thicknesses, their ends overlapping each other; and upon this floating bed was spread a thin layer of gravel, on which the sleepers, chairs, and rails were laid in the usual manner. Such was the mode in which the road was formed upon the Moss.

It was found, however, after the permanent road had been thus laid, that there was a tendency to sinking at those parts where the bog was the softest. In ordinary cases, where a bank subsides, the sleepers are packed up with ballast or gravel, but in this case the ballast was dug away and removed in order to lighten the road, and the sleepers were packed instead with cakes of dry turf or bundles of heath. By these expedients the subsided parts were again floated up to the level, and an approach was made toward a satisfactory road. But the most formidable difficulties were encountered at the centre and toward the edges of the Moss, and it required no small degree of ingenuity and perseverance on the part of the engineer successfully to overcome them.

The Moss, as has been already observed, was highest in the *When the Liverpool directors went to inspect the works in progress on the Moss, they were run along the temporary rails in the little three-feet gauge wagons used for forming the road. They were being thus impelled one day at considerable speed when the wagon suddenly ran off the road, and Mr. Moss, one of the directors, was thrown out in a soft place, from which, however, he was speedily extricated, not without leaving a deep mark. George used afterward laughingly to refer to the circumstance as "the meeting of the Mosses."