IN the course of a paper submitted to the Societe des Inghieurs Civils de France on April 23rd, 1931, describing the views of M. Freyssinet concerning Ferro-Concrete Bridges of very great span, I endeavoured to show how this eminent French engineer had come to the conclusion that a heterogeneous material such as reinforced concrete intelligently designed could be a structural material far superior to any homogeneous material such as steel of the highest quality; and how he strove for producing such a reinforced concrete, of quality much higher than what we used to consider at that time the highest grade of this material. It was these efforts which led M. Freyssinet to evolve what we know now as pre-stressed concrete, and on 19th March, 1936, I had the privilege of delivering before you, in M. Freyssinet’s presence, my English adaptation of his paper “A Revolution in the Technique of the Utilisation of Concrete,” in which were described the further developments in his ideas, and also a few examples of application of the new methods. T, J. Gueritte and Dr. K, W, Mautner