Fig. 38.
Fig. 39.
Fig. 40.
The Front Sight ([Fig. 40]) is attached to the right rim-base, and consists of the base a, the standard b, and the cylinder c, all formed in one piece. The cylinder c is a bushing open at both ends, the interior being formed of two conical frustums c′ joined at their smaller bases and having at this junction cross-wires (+), d, of platinum, which give the exact centre of the sight. In the new sights the cross-wires of watch-spring are placed diagonally (X). The cross-wires are used with the peep of the breech-sight, and the point e on top is used with the open sight.
Fig. 41.
The Breech-sight ([Fig. 41]) consists of a tangent scale affixed to a circular base revolving in a plane normal to the axis of the piece to compensate for inclination of trunnions when on uneven ground. The scale moves laterally on its base to correct for wind and drift, and bears a spirit-level, f. Along the vertical limb, C, of the sight, which is slotted, moves an eye-piece, D, actuated by a screw, d. This eye-piece (bearing the peep-sight d′) extends on either side of the slot, the lower edge being horizontal and bevelled. The one on the right is graduated into ten equal parts. (The vertical limb being graduated into degrees (0 to 15°), and then sub-divided by diagonals into sixths, a diagonal scale of equal parts reading to minutes is obtained. The rear sights now being issued have range scales in yards for shell and shrapnel engraved upon the sight in addition to the degree scale. The scale of yards for shrapnel on the rear face of the sight, left side, is arranged with diagonal lines, to be read in the same manner as the degree scale. Each diagonal embraces 250 yards of range, and there are five divisions on the upper edge of the slide, by which this space is sub-divided, so that the intervals of 50 yards in range are read directly from the scale.