Correspondence between John Nye and Michael Berry concerning dislocations and ultrasonic echo sounding Discussing a Cooperative Award in Pure Science (CAPS) from the Science Research Council for a stident to carry out laboratory research into the use of ultrasonic echo sounding for detecting defects and cracks in solids. Also contains correspondence relating to a joint paper being written by Nye and Berry on dislocations ['Dislocations in wave trains' published in Proceedings of the Royal Society A in 1974]. The folder includes a copy of the referee comments on the paper 1973-1974