This report outlines an experimental investigation into the mechanism of liquefaction. The investigation is centred on the relationship between the pore pressure build up in a sand sample, and the energy input to that sample by a cyclic load. Cyclic triaxial tests were used to establish the form, if any, of this relationship. A large portion of the duration of the experimental investigation was spent in developing a workable test procedure. The development continued with the construction of an electronic integrator specifically for the testing work. This device facilitated the recording of a plot of the pore pressure versus work input to the sample, continuously, throughout the duration of a test. A simple theory enabling prediction of the pore water pressure response to a given energy input at a known confining pressure is proposed. Comparison of the theoretical results with the measured traces for five analysed tests indicates that there is some merit to this description of the mechanism of the liquefaction of sands. The report concludes by emphasising this promise and suggesting that detailed future research along similar lines is needed.