Patent GB-191516319-A (GB)
Title: Improvements in Sights for Guns.
Inventor: SINCLAIR THOMAS CHARLES
Filed: 1915-11-19
Abstract: 16,319. Sinclair, T. C. Nov. 19. [Cognate Application, 6505/16.] Sights and methods of sighting.-Relates to sighting-apparatus for guns, and comprises means whereby two lines of sight or indications thereof are simultaneously presented to an observer, and serve to enable the direction, in the sense of both deflexion and elevation, and also the rate of travel of a moving target to be measured or observed in the field of the observing-instrument. One line of sight is fixed and corresponds to, or may be connected with, the ordinary gun sights, and may receive the ordinary sight adjustments for range, deflexion, &c., while the other line of sight is movable in any direction in relation to the fixed line of sight. Various constructional arrangements are described, all based upon the principle that if the two lines of sight are first in coincidence and moving with the gun to keep the image of a moving target central, then if the gun be stopped, together with one of the lines of sight. and the other line of sight be adjusted to follow the movement of the target for a time interval equal to the time of flight of the shot for the estimated range, the observed displacement of the target in the field of the sighting-instrument serves as a measure of the lead to be put upon the gun. The lead is put on by sighting through a point in the field of sight, diametrically opposite and equidistant from the centre relatively to the final position of the movable line of sight in the trial observation. This gives the required correction both as to elevation and denexion, the device being rotatable, so that the movement of the line of sight is in the apparent line of flight of the target. In the form shown in Figs. 12, 13, and 14, the graduated screen A forming the field of view of the instrument is carried by a frame J on a tube K which is slidable and rotatable on a tube H in which the image-projecting lens B<2> is mounted. A pair of pointers F, F<1> are carried by a rod or shaft G, being mounted on oppositely-threaded parts so that, as the rod is rotated, the pointers are simultaneously moved equally and oppositely. Thus if one pointer is caused to follow the target, the other pointer indicates the correction to be made in sighting the gun. The tube K is slid backwards and forwards on the tube H to focus the image, and is rotated thereon in order to bring the line of movement of the pointers into parallelism with the apparent direction of movement of the target. The rod G is mounted in the frame J in bearings J<3> and is actuated by means of a milled head G<1> or the like. The extent of the adjustments may be indicated by the rotation of a graduated drum or sleeve G<2> past a mark on the frame J. To facilitate observations, a binocular eyepiece L may be fitted in the end of a hood or bag M attached to the frame J or other part. The eyepiece L may be secured by a strap to the head of the observer. The invention is shown diagrammatically in other forms. In the arrangement shown in Figs. 3 and 4, a pair of lenses C and B are assumed to be in coincidence initially and arranged so that the focal axis is at right-angles to the screen A. Thus while the gun follows the target, the images projected by the two lenses are theoretically coincident and central as at A<1>. To determine the lead, the gun is stopped together with the lens B and screen A, with a result that the image projected by this lens appears to travel outwards, as at B The lens C is meanwhile manipulated to keep the image projected thereby central, as at A<1>. The corrected line of sight is then obtained by transferring the lens C to a diametrically opposite and equidistant position in relation to the lens B, the line of sight passing through the lens C and the centre A<1> of the plate. In this arrangement, the images projected by the two lenses would be rendered coincident in practice by the use of deflecting means, such as a prism. In a further modification, a single projecting-lens is arranged to be swung about its centre together with the screen A to follow the target maintaining the image central, the displacement being indicated by a fixed pointer. Instead of a pair of pointers as shown in Fig. 12, a single pointer on a screwed rod may be employed.