An apparatus has been developed for the semi-automatic measurement of specific heats from room temperature to the liquid-hydrogen range. A dynamic system, involving continuous heat input to the sample, is made possible by the use of a relatively small sample together with a large effective surface area for the heaters. Adiabatic conditions can then be maintained automatically. All data relevant to the specific heat determination (time, power input, and temperature) are recorded on a single chart. The operator is required only for periodic switching (which could in principle also be automatic). The specific heat of sodium has been studied between 55 and 315 degrees K with this apparatus. The predicted limits of accuracy ($\pm $0$\cdot $1%) appear to be approached rather closely. A small anomaly, showing some hysteresis effects, appears in the region of 200 degrees K.