Patent GB-387848-A (GB)
Title: Improvements in or connected with observation apparatus for use on moving platforms,such as ships
IPC: F41G5/14
Filed: 1932-03-03
Abstract: 387,848. Sighting instruments. BARR & STROUD, Ltd. and FRENCH. J. W., Caxton Street, Anniesland, Glasgow. March 3, 1932, No. 6414. [Classes 97 (i) and 97 (ii).] Observation apparatus for use on a moving platform comprises observation means which can he trained on a portion of the horizon and means for determining from the position of the observation means a stabilized reference plane passing through the observation station and containing the observed portion of the horizon. Means may be provided by which a target may be observed and referred to the stabilized plane. In one form a telescope 11 for observing the horizon 2, 4, 3, is carried upon a ring 12 pivoted about an axis 14 in a ring 13 supported by the axis 16 in the structure 15, which may be mounted high up at A in a ship 5. A handle 19 connected by pinion 21 and toothed quadrant 20 to the ring 13 and a handle 22 connected by pinion 24 and quadrant 23 to the ring 14 enable marks 18 on a diameter of the telescope field to be brought into coincidence with a portion of the horizon 17. The motions of the handles 19, 22 afford an indication of the inclination of the structure 15 in two planes at right-angles and these motions may be transmitted electrically or mechanically. In a modification two telescopes 11 may be carried on the ring 12 for use by two observers controlling respectively the handles 19, 22. In a further modification adapted to provide a stabilized plane without continuous reference to the horizon, a gyroscope is universally mounted in the structure 15 or in an extension of the ring 12. An optical system is provided to reflect an image of a mark fixed to the gyro casing into the telescope field and torques are applied, for example by hand, to precess the gyro into the correct position. The whole apparatus is rotatably mounted about a vertical axis. Two marks may be provided on the gyroscopic apparatus and used in conjunction with two telescopes. Fig. 13 shows apparatus requiring four operators. Two marks 36, 38 are provided on the inner and outer sides respectively of a ring which is caused to move with the universally mounted gyroscope 27. An image of the mark 36 passes via prism 41, lens 42, and prism 43 to the semi-reflecting surface 44 and passes from thence together with an image of the horizon obtained through the prism 49 and lenses 50, 51, through erecting prism 45, lens 46, and semi-reflecting surface 48 to the eyepieces 40, 62. The operators at the eyepieces 40, 62 maintain the gyro in the stabilized plane while an image of the mark 38 is projected by prism 64, lens 63, and prism 65 to the semi-reflecting surface 52, and from thence passes together with an image of an aerial target B, Fig. 1, obtained through adjustable prism 66 and lens 68, to prism system 53 whence it is passed to two eyepieces (not shown). The operators at these eyepieces train the sighting apparatus on the target in azimuth and altitude respectively. The system of prisms and lenses 49, 44, 43, 42 and 41, is rotatable as a whole around the central axis, the erecting prism 45 being rotatable in the same direction but by half the amount.