Origin of filar
Examples from the Web for filar
Transit Instrument, with reversing arrangement, illumination with oil or electric lamp, Filar micrometer with two eye pieces.Astronomical Instruments and Accessories|Wm. Gaertner & Co.
To Bouguer in 1748 is due the true conception of measurement by double image without the auxiliary aid of a filar micrometer, viz.
It can be used to measure the angular distance between objects too far apart for the filar micrometer.The Story of the Heavens|Robert Stawell Ball
Place the filar micrometer and the stage micrometer in their respective positions.
(c) By means of the Filar Micrometer (Ramsden's micrometer eyepiece).