ACOUMETER

n. Atk-u/me't-uSr, Lat., acoumetrum (from éxovew, to hear, and wérpov, a measure), Fr., acoumétre. Ger., It., acumetro, misuratore Sp., aconietro. An instrument originally devised by earing. Politzer’s Akumeter, Akoumeter, Gehôrme er. dell’ udito. Wolke and Itard for measuring the acutene of a., the most recent, consists of a horizontal steel cylinder, 28 mm. long and45mm. thick, connected by means of a tightly fitting _ screw wit! a vertical vulcanite column, Above the place of attachment of the cylinder, a percu ion hammer, which can he turned round its axis, is fastened in an oval orifice of the vulcanite column, and produces the tone by falling on the steel cylinder. As the intensity of the sound depends on the height from which the hammer falls, in order to produce in all instruments an equal height, a small piece of vulcanite, furnished with a soft-rubber plate, is fixed at the posterior periphery of the column as a check, on which the posterior (short) arm of the hammer is pre ed. At either end of the column there is a flat semicircle, for grasping the instrument with two fingers. Below the upper semicircle, parallel with the axis of the percu ion hammer, there is a ring on the vuleanite column, into which a pin, to which a round metal plate is attached, can be inserted. This is for testing the conduction of the cranial hones, by bringing the metal plate into contact with the temple or with ‘the mastoid proce , while the meatuses are closed. [F.]