EYE MOVEMENTS1 are an important physiological activity. For many purposes it is no longer sufficient to observe gross eye movements subjectively. Instruments must be used which can measure objectively eye movements over a large range and to a small angle, follow rapid changes for long stretches of time and be used under a variety of experimental and clinical situations. There are three fundamental methods by which eye movements can be objectively recorded (Duke-Elder2). The first is by a mechanical (or hydraulic) system attached directly to the eyeball. This crude method has been completely supplanted by the other two. The optical method of recording rotations of the eyes is better known. Reflections from the cornea—the first Purkinje image—of a light source is recorded photographically on a moving film. There are several disadvantages to this procedure. The head is immobilized, and generally a strong glare comes from the light source.