A Mössbauer-effect apparatus, suitable for either lecture demonstration or inclusion in an undergraduate teaching laboratory, is described. Use of a rotating tilted disk to provide linear motion between source and absorber simplifies the construction and calibration of the experimental equipment. Some features are as follows: calibration of velocity by timing rotations of the wheel with a stopwatch, provision of a large-scale motion which graphically illustrates the first-order relativistic Doppler shift and its effect on monochromatic radiation, and sufficient precision to measure the nuclear Zeeman splitting in iron of theFe57mtransition. Construction details, as well as instructions for the use of the equipment, are given.