a. [f. BI- pref.2 1 + FILAR, f. L. fīl-um thread + -AR.] Fitted or furnished with two threads; spec. applied to apparatus for measuring minute distances or angles; also for suspending a body so that it has a very slight directive force in a definite plane, with a view to the measurement of minute forces, etc. Bifilarly adv., in a bifilar manner, by means of two threads.
1870. R. Ferguson, Electr., 26. Gauss’s bifilar magnetometer.
1879. Thomson & Tait, Nat. Phil., I. I. § 435. The Bifilar Suspension … was used also by Gauss in his bifilar magnetometer for measuring the horizontal component of the terrestrial magnetic force.
1884. Harper’s Mag., Sept., 644/1. A copper disc suspended bifilarly.
