Introducing the paper, Mr. Needham said that a testing rig had been evolved capable of taking beams up to 25 ft span and 2 ft 6 in. deep with two 20-ton loads, hydraulically applied at the quarter-points. It had been intended for testing a wide range of prestressed girder designs. The loads needed to impart a load factor of two, on a quarter-scale model of the girder tested at MEXE, amounted to approximately 7 tons per jack; thus the capacity of the rig would enable much stronger models to be tested.