tever might be the form of the tube, the principle on which the
calculations were founded was equally applicable, and could not fail to
lead to equally accurate results." {327} Mr. Stephenson accordingly
announced to the directors of the railway that he was prepared to carry
out a bridge of this general description, and they adopted his views,
though not without considerable misgivings.

While the engineer's mind was still occupied with the subject, an
accident occurred to the _Prince of Wales_ iron steamship, at Blackwall,
which singularly corroborated his views as to the strength of
wrought-iron beams of large dimensions. When this vessel was being
launched, the cleet on the bow gave way, in consequence of the bolts
breaking, and let the vessel down so that the bilge came in contact with
the wharf, and she remained suspended between the water and the wharf for
a length of about 110 feet, but without any injury to the plates of the
ship; satisfactorily proving the great strength of this form of
construction. Thus, Mr. Stephenson became gradually confirmed in his
opinion that the most feasible method of bridging the strait at Menai and
the river at Conway was by means of a hollow beam of wrought-iron. As
the time was approaching for giving evidence before Parliament on the
subject, it was necessary for him to settle some definite plan for
submission to the committee. "My late revered father," says he, "having
always taken a deep interest in the various proposals which had been
considered for carrying a railway across the Menai Straits, requested me
to explain fully to him the views which led me to suggest the use of a
tube, and also the nature of the calculations I had made in reference to
it. It was during this personal conference that Mr. William Fairbairn
accidentally called upon me, to whom I also explained the principles of
the structure I had proposed. He at once acquiesced in their truth, and
expressed confidence in the feasibility of my project, giving me at the
same time some facts relative to the remarkable strength of iron
steamships, and invited me to his works at Millwall, to examine the
construction of an iron steamship which was then in progress." The date
of this consultation was early in April, 1845, and Mr. Fairbairn states
that, on that occasion, "Mr. Stephenson asked whether such a design was
practicable, and whether I could accomplish it: and it was ultimately
arranged that the subject should