We soon came in sight of the tubular bridge carrying the railway across the Straits.  The distance between the cliffs on either shore is eleven hundred feet.  It was curious, as we sailed under it, to look up to a height of one hundred and four feet, and to see these two enormous tubes above our heads.  Their total length is one thousand eight hundred and thirty-three feet, which includes two hundred and thirty feet at either end resting on the land.  The tubes are composed of wrought-iron plates, three quarters of an inch thick, tightly riveted together, the one carrying the up, and the other the down line.  The bridge is supported by three vast piers, measuring sixty-two feet by fifty-three feet at their base.  This wonderful work is considered to surpass that of the Menai Bridge.  It may be asked how these tubes could ever have been got up to their present positions.  This was accomplished by means of hydraulic presses of the most powerful description; indeed, it is asserted that one of them could throw a stream of water twenty thousand feet into the air,--above five times higher than Snowdon, and five thousand feet higher than the summit of Mont Blanc.  The bridge was commenced in 1846 by Robert Stephenson, and the first train passed through it on the 1st of March, 1850; since which time no accident has happened to it.