Patent GB-129327-A (GB)
Title: Improvements in Rangefinding Methods and Apparatus.
Inventor: ROUTIN JOSEPH LOUIS
IPC: G01C3/10
Filed: 1917-10-18
Abstract: 129,327. Routin, J. L., (Assignee of Maison Breguet). Oct. 20, 1916, [Convention date]. Range-finders.-The height of an aerial object. and hence its range, is determined by means of an apparatus based on the formula h b tan #- tan a, h being the height, b the known length of a baise between two sighting-stations, and a and # the angles made with the vertical by the projections of the lines of sight to the object in the vertical plane containing the base; the formula is proved in the Specification, and the apparatus may be modified for use with objects on the surface of the earth. The apparatus. shown diagrammatically, comprises sighting- telescopes 1, 2 at the ends of the base rotatable by handles 5, 6 on screwed rods 7, 8 bearing nuts 9, 10 engaging in slotted arms 11,12 integral with the telescopes and turning about axes 3, 4, the amounts of movement of the nuts 9, 10 being measures of the tangents of the angles a, #. The rods 7, 8 are geared to contact-arms 17, 18 which travel over rheostats 13, 14, the rheostats being one in each branch of a divided electric circuit, and the arms being connected respectively to the terminals of a volt-meter 19. The circuit comprises a battery 15, wire a, branching wires b, s, slip-rings c, t, rheostats 14, 13, slip-rings w, p, and wires x, q which unite in a wire v connected through a rheostat 16 to the battery, The arms 17, 18 engage respectively with contacts n, e which are connected by wires m, f to a switch 24, and thence by wires j, i to the terminals of the volt-meter 19. When the sighting-telescopes are parallel, the arms 17, 18 are also parallel, and the needle of the volt-meter shows no deflexion. As the telescopes are converged on to the object, the arms are also moved, and the needle of the volt-meter is deflected over a scale, the amount of deflexion depending upon the difference between the movements of the nuts 9, 10, and consequently upon tan # tan a. The scale may therefore be graduated directly in heights. The rheostats 13, 14 may be rotated about the axes of the arms 17, 18 by means of handles 20, 21, as indicated diagrammaticaliy, revolution-counters 22, 23 being provided. By this means, when, by adjustment of the telescopes, either arm 17, 18 comes to the end of its rheostat, the rheostat may be rotated so that the arm again commences to travel over the rheostat. When the telescopes are finally sighted on the object, the numbers of revolutions of the rheostats may be communicated to the volt-meter station, and their difference determined. The readingof the volt-meter needle is then taken on a corresponding scale, the instrument being provided with scales calibrated in accordance with a difference of one, two, &c. revolutions of the rheostats. Resistances may be placed in the volt-meter circuit to vary the sensibility of the voltmeter, and the connexions and switch 24 permit the volt-meter to be placed in circuit with the battery 15 and rheostat 16 only, so that the value of the current passing through the rheostat 16 may be determined.