electric annunciator

A form of annunciator, used in large private houses and hotels, in which a current wire is the means of shifting the shield covering the number aperture on a dial, or in some other way indicating the number of the room. The guest in his room touches a button upon the wall; the circuit being made or broken, the effect is evi denced by the exposure of the room number on the dial. Other forms of annunciator are used for automatically recording future engagements, the electrical mechanism being dependent upon clockwork. electric-apparatus, electrical-apparatus, s . Apparatus used for making discoveries in electricity, or for applying it to purposes useful to mankind. [ELECTRIC-BATTERY, ELECTRIC-MACHINE, .] electric-aura, s. Pharm.: A current or breeze of electrified air employed as a mild stimulant in electrifying delicate parts, as the eye. electric-balance, s . An instrument for measuring the attractive or repulsive forces of electrified bodies. A form of electrometer, consisting of a graduated arc supported by a projecting plate of bra which is attached to the perpendicular column. A wheel, the axis of which is supported on anti-friction rollers, and is concentric with that of the graduated arc, carries an index. Over this wheel, in a groove on its circumference, pa es a line, to one end of which is attached a light ball of gilt wood, and to the other a float, which consists of a gla tube about one-fifth of an inch in diameter, terminating in a small bulb, so weighted that the index may point to the center of the graduated arc. The difference between the weights of the float when in and out of water is known, and the diameter of the wheel carrying the index is such, that a certain amount of rise or fall of the float causes the index to move over a certain number of graduations on the arc.