No. 1 gun fires, elevation 4500 yds., P.S., round observed −
No. 2 gun fires, elevation 4600 yds., P.S., round observed +
B.C. orders: “Remainder 4500, one round gun fire, 3 seconds.”
| No. 3 elevation 4500 yds. T.S. corrector 150 air No. 4 elevation 4500 yds. T.S. corrector 160 air No. 5 elevation 4500 yds. T.S. corrector 160 graze No. 6 elevation 4500 yds. T.S. corrector 180 graze |
B.C. selects corrector 160 and goes to “section fire.”
The battery now begins to fire “for effect.”
No. 1 elevation 4500 yds. T.S. corrector 160 air
No. 3 elevation 4500 yds. T.S. corrector 160 air
followed by Nos. 5, 2, 4 and 6.
There is another method of ranging, viz. with time shrapnel only. In this the principle is that several shells, fired with the same corrector setting, but at different elevations, will burst in air at different points along one line. Bursts high in the air cannot be judged, and it is therefore necessary to bring down the line of bursts to the target, so that the bursts in air appear directly in front or directly in rear of it. Rounds are therefore fired (in pairs owing to possible imperfections in the fuzes) to ascertain the corrector which gives the best line of observation. This found, the target is bracketed by bursts low in the air observed + and −, as in the ordinary method with percussion shrapnel.
The operations of finding the “line of fire” and the proper elevation may be combined, as the shells in ranging can be made to “bracket” for direction as well as for elevation. The line can be changed towards a new target in any kind of direct and indirect laying, in the latter case by observing the angle made with it by the original line of fire and giving deflection to the guns accordingly. Further, the fire of several dispersed batteries may be concentrated, distributed, or “switched” from one target to another on a wide front, at the will of the commander.
31. Observation of Fire, on the accuracy of which depends the success of ranging, may be done either by the battery commander himself or by a special “observing” party. In either case the shooting is carefully observed throughout, and corrections ordered at any time, whether during the process of ranging or during fire for effect. The difficulties of observation vary considerably with the ground, &c., for instance, the light may be so bad that the target can hardly be seen, or again, if there be a hollow in front of the target, a shell may burst in it so far below that the smoke appears thin, the round being then judged “over” instead of “short.” On the other hand, a hollow behind the target may cause a round to be lost altogether. Ranging with time shrapnel has the merit of avoiding most of these “traps.” The “French system of fire discipline,” referred to below, has this method as the usual procedure.