Barretter

Bar"ret*ter, n. [OF. bareter to exchange. Cf. Barter.] (Wireless Teleg.)

Defn: A thermal cymoscope which operates by increased resistance when subjected to the influence of electric waves. The original form consisted of an extremely fine platinum wire loop attached to terminals and inclosed in a small glass or silver bulb. In a later variety, called the liquid barretter, wire is replace by a column of liquid in a very fine capillary tube.