Improvements in or connected with mechanical means and instruments for measuring vertical heights of aerial targets or horizontal distances, say, for surveying purposes

摘要

139,224. Barr & Stroud, Barr, A., and Stroud, W. Oct. 20, 1916. Range - finders. - Range-finders in which the indications are in accordance with a reciprocal scale are provided with means for measuring vertical heights or horizontal distances forming three sides of a triangle ABC, Fig. 5, one side AC is adjustable according to the reciprocal of the range and another side CB is always at right-angles to it and is geared to the range-finder so as to be at the angle of sight to the third side AB, the height being indicated upon a reciprocal scale on AB. Horizontal distances may be measured upon a part AH at rightangles to AB. In one form, Fig. 2, the working head of the range-finder drives a screw 10 through bevel-gearing, the distance CA thus representing the reciprocal of the range. An arm 12 is moved along the screw by a nut and is held at rightangles to the screw, the height being measured upon a reciprocal scale upon a member 13 which is maintained in vertical position. In a modified construction, Fig. 3, an horizontal-base rangefinder 1 is mounted in forks 2, 3 and is capable of ready detachment. The working head operates through rod and pinion, a rod 25 which carries a curved sector engaging the part 12 upon which the line CB is engraved; the part 12 thus does not partake of the angular movement of the head in its forks. This angular movement is transmitted by bevel-gears 35, 36 to the arm 13 upon which the reciprocal scale of heights is carried. The range-finder is detached from its forks by moving it axially to bring the bevel-gears out of mesh and then lifting it out; index points are marked on the gears to facilitate correct replacement. The range-finder may be of the type described in Specification 9520/88.