=The tripod= mount consists of a spring catch (a); clamping lever (N); elevation worm case (b); elevation worm knob (c); worm wheel support (d); angle of site micrometer (e); angle of site housing (f); angle of site vial holder (g); clamp screw handle (h); azimuth worm knob (i); azimuth micrometer (j); azimuth worm lever (k); azimuth scale (m); adjusting worm knob (n); and the vertical spindle clamping lever (p). The tripod, consisting of spindle bushing locking screws (t); tripod legs upper (r); tripod legs lower (q); clamping wing nuts (w); and locking clamp arms (x), is similar to that provided for the B. C. telescope and the aiming circle. Care and Instructions. =To set up the Range Finder.=—Set up the tripod as heretofore prescribed, take the range finder from its case, holding it with the eye piece toward the body, hook down. Place the instrument on the support and engage the spring catch (a). The instrument is then firmly seated on the tripod. Remove the protective hood from the eye piece and the rotating shutters (D) from the objective apertures. Loosen the locking lever so that the range finder may be made horizontal, then turn toward the target and clamp the lever. To dismount the range finder the operations are executed in an inverse manner. [Illustration: REAR VIEW RANGE FINDER.] [Illustration: RANGE FINDER.] =To Measure a Distance.=—Focus the eye piece. In very bright light or in thick haze use the amber ray filter in the eye piece. By means of the clamps and worm knobs of the azimuth mechanism and the worm knob of the elevation mechanism, lay the range finder on the target roughly by looking through the open sight on top of the instrument. Final adjustment in deflection is made by the adjusting worm knob (n) and in elevation by the elevation worm knob (c). Now, look into the instrument. The field of view is divided into two parts by a horizontal line. In the lower part the image is erect, in the upper part inverted. By turning the elevation worm knob (c), the images are lined up so that the same points will touch the dividing line. Now, by turning the measuring roller (M) on the right hand top side of the range finder, the upper image is shifted laterally until the same vertically disposed points of the target are exactly opposite each other. The range is then read on the range scale (H), which is protected by a sliding shutter (Q). In case the target is without prominent vertical features, such as a crest line, the distance is measured by first turning the instrument to a vertical position (Plate XV). This is accomplished by the clamp screw handle (h) on the tripod mount. Final adjustment in deflection is then made by the elevation worm knob (c), and in elevation by the clamping lever (N). Adjustments.