About midway between Conway and Bangor, Penmaen Mawr forms a bold and almost precipitous headland, at the base of which, in rough weather, the ocean dashes with great fury. There was not space enough between the mountain and the strand for the passage of the railway; hence in some places the rock had to be blasted to form a terrace, and in others sea-walls had to be built up to the proper level, on which to form an embankment of sufficient width to enable the road to be laid. [Picture: Penmaen Mawr. (By Percival Skelton.)] A tunnel 10½ chains in length was cut through the headland itself; and on its east and west sides the line was formed by a terrace cut out of the cliff, and by embankments protected by sea walls; the terrace being three times interrupted by embankments in its course of about 1¼ mile. The road lies so close under the steep mountain face, that it was even found necessary at certain places to protect it against possible accidents from falling stones, by means of a covered way. The terrace on the east side of the headland was, however, in some measure protected against the roll of the sea by the mass of stone run out from the tunnel, and forming a deep shingle bank in front of the wall. The part of the work which lies on the westward of the headland penetrated by the tunnel, was exposed to the full force of the sea; and the formation of the road at that point was attended with great difficulty. While the sea wall was still in progress, its strength was severely tried by a strong north-westerly gale, which blew in October, 1846, with a spring tide of 17 feet. On the following morning it was found that a large portion of the rubble was irreparably injured, and 200 yards of the wall were then replaced by an open viaduct, with the piers placed edgeways to the sea, the openings between them being spanned by ten cast-iron girders each 42 feet long. This accident induced the engineer to alter the contour of the sea wall, so that it should present a diminished resistance to the force of the waves. But the sea repeated its assaults, and made further havoc with the work; entailing heavy expenses and a complete reorganisation of the contract. Increased solidity was then given to the masonry, and the face of the wall underwent further change. At some points outworks were constructed, and piles were driven into the beach about 15 feet from the base of the wall, for the purpose of protecting its foundations and breaking the force of the waves. The work was at length finished after about three years’ anxious labour; but Mr. Stephenson confessed that if a long tunnel had been made in the first instance through the solid rock of Penmaen Mawr, a saving of from £25,000 to £30,000 would have been effected. He also said he had arrived at the conclusion that in railway works engineers should endeavour as far as possible to avoid the necessity of contending with the sea; {324} but if he were ever again compelled to go within its