Patent GB-190823307-A (GB)
Title: Improvements in the Sighting of Ordnance.
Inventor: SCOTT LOTHIAN KERR
Filed: 1908-11-02
Granted: 1910-02-02
Abstract: 23,307. Scott, L. K. Nov. 2. Sights and methods of sighting. -Relates to howitzer sights, and consists in the provision of separate cams for elevating and deflecting the sight for each different charge of powder employed, each cam being cut for a certain field of ranges over which the steepest angles of descent of the projectile are obtained by using the powder-charge corresponding to the cam. A single range scale only is employed, and the points at which a fresh cam and powder-charge must be substituted are suitably indicated. Fuse scales are provided upon the sight from which the fuse-setting for a given range and powder-charge is read directly. In the construction shown, an " all-round " sighting-device 1, preferably of the kind described in Specification No. 20,203, A.D. 1904, is elevated by a roller R, Fig. 4, which is traversed along a cam-curve E<1> by screw-gearing and pinions W, W', the latter of which is carried by the spindle of a range-drum h of the kind described in Specification No. 595, A.D. 1895. The cam E<1> is radially mounted on a sleeve E, upon which the cams E<2>, E<3>, E<4>, for three other and different charges are also mounted, as shown in Fig. 3, so that when the powder-charge is changed the corresponding cam is brought into contact with the roller R<1> by rotating the sleeve E upon a bolt e. The correction for drift is made by tilting a transverse level L by means of a roller R' which is traversed along one of a series of camsurfaces D<1> ... D<4>, Fig. 5, arranged beneath the level and corresponding to the elevation cams E' ... E<4>, and afterwards cross-levelling the sight by rocking the supporting frame p upon the trunnions T'. The roller R<2> is carried by a lever n, which is pivoted at e' to an arm e<3> on the bolt e, and is rocked during the elevation of the sight by the relative motion between a fixed pin m and a slot n<1> in the lower end of the lever. A pin e<3> on the sleeve E works in a groove K in the bolt e, so that when the elevation cam is changed the bolt is moved lengthways and shifts the roller R' on to the corresponding drift cam. The slider t which carries the roller R<1>, and the reader h<1> of the range drum h, are both provided with cursors w which move over identical fuse scales f. The cams E<1> ... E<4> may be cut so as to give all angles of elevation from zero to the maximum of 40 degrees, or, as shown, elevations from zero to 20 degrees. The corrections for the angle of site are given by an elevating-gear S F<1>, and the cams are cut so as only to give the additional angles up to 40 degrees. The elevation cams may be mounted side by side on a rotatable spindle, or they may be all combined into a single rotatable cam ; in either of these cases, the roller R<1> is attached to the underside of the frame A of the sight, and the cams are geared with the range drum h. The drift correction may be made by turning a limb which supports the sighting-device about a vertical pivot, as described in Specification No. 6539, A.D. 1907, by means of a roller which can be adjusted to work against any one of a series of cams provided upon a vertical arc depending from the limb as the sight is elevated. Means are in this case provided for maintaining the longitudinal level 10 parallel to the axis T' T<1>. The elevation and drift cams may also be combined into one rotating cam-body, the sight-supporting limb being deflected for the drift correction by a lever mechanism one arm of which bears against the drift cams.