, said that the Author had been Dfr. Harrison good enough to give an account of the substructure of the Tower Bridge. He trusted that when the bridge was finished the Author would also give an account of the superstructure. The bridge was original both in conception and in design and it was important that a complete account of it should appear in the Minutes of Proceedings. He had much satisfaction in proposing a vote of thanks to the Author for his useful and practical Paper. cussion of this important Paper, noticed one point to which he should like to refer, viz., the strengthof the toe which was carried all round the foundation at the base of the concrete, for the purpose, he presumed, of increasing the superficial area of the clay on which the bridge stood. He had done such a thing himself and so far as he k:new it had answered very well. He thought, however, that there must be in this case a considerable tensile strain in the base of the concrete at the heel of the toe. The settlement of such a bridge upon the clay tended to take the form of a curved line, and the pressure must, therefore, be very severe upon the toe. H e believed that, unless there was timber or iron in the base (he should be glad to know if there were such), a considerable tensile stress would be thrown upon the concrete at the point he had indicated, tending to crack if not to shear it. the subject of the Tower Bridge at the present stage of its progress, because there was enough detail in this structure for two Papers, one upon the foundations and one upon the superstructure. A bridge must not only be looked upon by itself in elevation, but the circumstances of the site should be duly considered in every case. The circumstances of the present site were that there were important wharves abore the bridge ; and by building a bridge with an open span, those wharves need not be purchased and need not be W) fully compensated. The two river-piers permitted the construction of suitable arrangements for an opening central span ; and it would be seen that, owing to the area required for the pressure on the base, there was room for the counterbalance in the 70-foot width to assist the opening. After all 70

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The first effect of the outbreak of war in 1939 was greatly to reduce work in pure science and to direct effort to projects relevant to the war. After the war there was a very rapid expansion to a level much exceeding that of the 1930s. The work done during the war in nuclear physics, electronics, instrumentation, radar and rocketry was the basis of this expansion. Successes during the war had given science a new image with the public and with the government; money and facilities were available for fundamental science on a scale more than 10 times that of pre-war days. Wartime work had also had a profound effect on the expectations and style of work of physicists. They had learnt how to obtain and handle large resources.

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