Page:Walker (1888) The Severn Tunnel.djvu/223

136 additional precaution against the Great Spring, for fear of the rising heading (which had not been thoroughly secured, and was in bad ground) giving way, a large head-wall of brick in cement was built across the full-sized tunnel, 260 feet west of the Sudbrook Pit; at the same time a concrete wall was built round the boilers, engines, and pit at the Marsh, so that even if we were visited by another wave of corresponding height, we should at least save that pit from being drowned, and the fires in the boilers from being extinguished.

The height of the tidal wave was found to be 10 feet above the calculated height for the tide on that night.

Large quantities of timber, which had been stacked at the Marsh Pit, were floated away to some distance, and one large larch-tree, 15 inches in diameter, was landed upon the top of the post-and-rail fence east of the Marsh Pit; the fence being 4 feet 6 inches above the level of the meadows.