FREAKS OF CONCEALED BOGS.
Great difficulties have often been encountered by engineers in carrying earth embankments across low grounds, which, under a fair, green surface, concealed the remains of ancient bogs, sometimes of great depth. Thus, on the Leeds and Bradford Extension, about 600 tons of stone and earth were daily cast into an embankment near Bingley,
and each morning the stuff thrown in on the preceding day was found to have disappeared. This went on for many weeks, the bank, however, gradually advancing, and forcing up on either side a spongy black ridge of moss. On the South-Western Railway a heavy embankment, about fifty feet high, crossed a piece of ground near Newham, the surface of which seemed to be perfectly sound and firm. Twenty feet, however, beneath the surface an old bog lay concealed; and the ground giving way, the fluid, pressed from beneath the embankment, raised the adjacent meadows in all directions like waves of the sea. A culvert, which permitted the flow of a brook under the bank, was forced down, the passage of the water entirely stopped, and several thousand acres of the finest land in Hampshire would have been flooded but for the exertions of the engineer, who completed a new culvert just as the other had become completely closed. The Newton-green embankment, on the Sheffield and Manchester line, gave way in like manner, and to such an extent as to spread out two or three times its original width. In this case it was found necessary to carry the line across the parts which yielded, under strong timber shores. On the Dundalk and Enniskillen line a heavy embankment twenty feet high suddenly disappeared one night in the bog of Meghernakill, nearly adjoining the river Fane. The bed of the river was forced up, and the flow of the water for the time was stopped, and the surrounding country heavily flooded. A concealed bog of even greater extent, on the Durham and Sunderland Railway, near Aycliff, was crossed by means of a double-planked road, about two miles in length. A few weeks after the line had been opened, part of the road sank one night entirely out of sight. The defect was made good merely by extending the floating surface of the road at this portion of the bog.
—Quarterly Review.