“It will be noticed no 1’s were made. Assuming the height above the ground of the average mounted soldier as 8 ft., had a troop of cavalry mounted been 200 yards in front of the machine guns in the third experiment, the line of sight would have struck about the backs of their horses, and all bullets would have gone over the riders with at least 4 feet to spare, as proved by the experiment.... The troop mounted could have moved forward to within 100 yards of the target and would not have been struck by the bullets.”
The methods of carrying out indirect covering fire will vary according to the nature of the position selected and the way the guns are to be laid. This is one of the few occasions when a battery or two may have all their guns in line close together. If the slope is a steep one, they may be pushed up close to the crest, but on a gentle slope they must be placed sufficiently far back to avoid the forward effect of shrapnel bursting on the crest line.
The battery commander will select the position for the guns and will then give each gun or section a section of front to fire on. The method of marking off this section is as follows: two iron rods about 3 ft. long for each gun are painted white, and are then “laid off” from the gun to the target, in an exact line, the first being on the reverse slope a few yards short of the crest; the next on or just behind the crest line. By aligning the gun on the rods, fire is brought on the centre of the target; should traversing fire be required, the limits may be marked by similar sticks on either side.
There are two methods of laying the gun. (1) By observation of fire. (2) By quadrant elevation. The first method has been already described, and the second must be done by using the following table in conjunction with an instrument for elevating the gun at the required angle; but it must be remembered that each gun will require adjusting to its own angle of elevation to suit its known error at each range. Thus a gun which is known to require sighting at 900 yards when firing at 1,000 should receive 1° 10½ and not 1° 25½. When proper instruments are not obtainable, very fair results may be obtained by using an ordinary clinometer. The necessary allowance for the height the gun is above the target must be made, or, in other words, the angle of sight as shown by the clinometer must be deducted from the quadrant elevation given on the gun.
Diagram IV
TO SHOW METHOD OF LAYING BY AIMING POSTS
aa. Aiming Posts (about 15x apart and some distance in front of gun.)
ttt. Targets.