An apparatus has been constructed to record the thermoluminescence of a mineral in the form of a powder or a single crystal at temperatures from --100 d C to +400 d C. Glow curves are obtained by heating the sample at a constant rate and recording the intensity of thermoluminescence as a function of temperature. The apparatus has provision for the irradiation of the sample with x rays or ultraviolet light and for measurement of the induced luminescence during any part of the experiment. Upon termination of the irradiation the measurement of the luminescence can be continued at any desired temperatare and rapidly decaying phos phorescence can be detected. In all these experiments the sample remains undisturbed, and the problems associated with ihe heterogeneiiy of the sample are thus reduced. (auth)