such matters". Fairbairn began a series of practical experiments on various tube shapes and enlisted the help of Eaton Hodgkinson "distinguished as the first scientific authority on the strength of iron beams" It became apparent from Fairbairn's experiments that- without special precautions - the failure mode for the tube under load would be buckling of the top plate in compression, the theoretical analysis of which gave Hodgkinson some difficulty. When Stephenson reported to the directors of the railway in February 1846, he attached reports by both Hodgkinson and Fairbairn. From his analysis of the resistance to buckling of tubes with single top plates, Hodgkinson believed that it would require an impracticably thick (and therefore heavy) top plate to make the tubes stiff enough to support their own weight, and advised auxiliary suspension from link chains. However, Fairbairn's experiments had moved on from those covered by Hodgkinson's theory to include designs in which the top plate was stiffened by 'corrugation' (the incorporation of cylindrical tubes). The results of these later experiments he found very encouraging; whilst it was still to be determined what the optimum form of the tubular girder should be "I would venture to state that a Tubular Bridge can be constructed of such powers and dimensions as will meet, with perfect security, the requirements of railway traffic across the Straits" although it might require more materials than originally envisaged and the utmost care would be needed in its construction. He believed it would be 'highly improper' to rely upon chains as the principal support of the bridge. Under every circumstance, I am of opinion that the tubes should be made sufficiently strong to sustain not only their own weight, but in addition to that load 2000 tons equally distributed over the surface of the platform, a load ten times greater than they will ever be called upon to support. In fact, it should be a huge sheet-iron hollow girder, of sufficient strength and stiffness to sustain those weights; and, provided that the parts are well-proportioned and the plates properly riveted, you may strip off the chains and have it as a useful monument of the enterprise and energy of the age in which it was constructed. Stephenson's report drew attention to the difference of opinion between his experts, but reassured the directors that the design of the masonry piers allowed for the tubes to be given suspension support,