To the Editor: —I herewith submit a description and an illustration of an improvised exophthalmometer. The instrument is inexpensive. An ordinary compass is used, and to the movable leg is added a grooved cross piece, the lateral rim of the orbit fitting into the groove. To the fixed leg is added a spatula which extrudes beyond the plane of the shorter leg by 18 mm. The patient's eye is anesthetized before the instrument is used. While the patient looks straight ahead, the `groove on the cross piece attached to the shorter leg is placed on the lateral rim of the orbit, and the longer leg is brought just up to the center of the cornea. The reading on the protractor scale in degrees is multiplied by three. This gives the amount of proptosis expressed in millimeters. The readings obtained with this instrument have been compared with those obtained with a