Electroscope

(e-lektro-skōp.) [Gr. skopea, to look.] (Elect.) An instrument for detecting the presence, and determining the kind, of electricity in any body. The original pith-ball pendulum is an E.; but, though some times convenient, it is not sufficiently delicate. Many succe ive improvements have been made in it, and have resulted in the form now generally used, which is called the gold-leaf E., and is due to Bennett. It consists of a small gla jar, to the upper end of which is attached a bra cap; in the centre of the latter is fixed apiece of gla tube; a wire pa es through the tube, having at its upper end a bra ball, and at its lower two narrow slips of gold-leaf, hanging together by one end of each. These slips remain parallel, and in con⚫tact, when the instrument is un electrified; but, when it is electrified by placing an excited body in contact with or near its bra ball, the lower extremities of the gold leaves fly asunder. The gla jar protects the gold leaves from injury. [s. 323]