Patent GB-313128-A (GB)
Title: Apparatus for mechanically solving right-angled triangles
IPC: G01C3/00
Filed: 1929-06-04
Abstract: 313,128. Akt.-Ges. C. P. Goerz Optische Anstalt. June 7, 1928, [Convention date]. Plane-trigonometry calculators. - Comprises apparatus for the solution of right-angled triangles from two known quantities, based upon the property of a sine curve that the square on the maximum ordinate is equal to the sum of the squares of two other ordinates separated by a distance corresponding to the angle II/2. The maximum ordinate a, Fig. 2, can thus represent the hypotenuse and the ordinates b, c, separated by a distance corresponding to II/2, will represent the sides of the right-angled triangle, such ordinates being at distances from the maximum ordinates corresponding to the hypotenuse angles of the triangle. The sine curve is represented by the ellipse of intersection of a plane with the surface of a right circular cylinder, the lengths being measured along generatrices of the cylinder between the ellipse and the circle of intersection of a plane normal to the axis passing through the centre of the ellipse, Fig. 1. The apparatus is described in connection with a range-finder for use with aerial targets, and is arranged so that indications of the height and horizontal distance of the target are given on scales which do not partake in the adjustment of the range-finder for altitude. The range-finder being sighted on the target, coincidence of the partial images is brought about by the relative rotation of the prisms 7, 7<1>, from the roller 47, Fig. 5, through the toothed arc 41 and yoke 23, Fig. 6, by which the arc 54 is moved simultaneously with the circular ring 26. The connections between the arc 54 and the spindle 11 rotating the prisms are such that the movement of the arc 54 and the ring 26 is directly proportional to the range of the target, which is read off the helical scale 48'. Rings 28, 29 are mounted on the ring 26 and are provided with projections 30, 31 ending in cylindrical pins 30<1>, 31<1> carrying sleeves 33, 34 which are rotatable on the pins 30<1>. 31<1> and are provided with divisions 32. Squared portions 33<1>, 34<1> of the sleeves 33, 34 slide between guide ribs 36, 35 arranged in wing-like hollow projections 38, 37 situated at an angle of 90<0> relatively to each other on the casing 14 so that the projection 37 is horizontal and the projection 38 is vertical. Slots in the projections are fitted with scales 39, 40 which give the horizontal distance and the height of the target to a scale dependent on the scale of the range-finder. In operation the target is followed by the range-finder and the range is indicated on the range scale 48, the movement of the knurled roller 47 to obtain coincidence being transmitted to the ring 26 and the tilting of the range-finder to sight the target affecting the final adjustment of the divisions 32 on the sleeves 33, 34 on the scales 39, 40 giving the horizontal distance and the height required. A modified form is described in which the movement of the roller 47 is transmitted to the ring 26 by bevel wheels and a further form, shown in Fig. 10, has the two scales for horizontal distance and height arranged in slots on the surface of a fixed sphere, but otherwise operating as described in connection with Figs. 5 and 6.