48. Tracing the Battery.—The battery is traced under the direction of an engineer officer by one or two tracing parties, each composed as follows: 1 non-commissioned officer with a 6-foot measuring-rod and tracing-lantern, and 4 sappers, one carrying a measuring-tape and bundles of pickets, one a field-level, one several tracing-tapes, and one a mallet or hand-axe; about 75 pickets and 1200 feet of tracing-tape should be provided. The line of fire of the first gun of the battery (xy, [Pl. V], Fig. 46) is accurately laid out and marked by daylight. At dusk one party drives a picket at I, where the directrix crosses the projection of the base of the interior slope, and from this as an origin lays out the cutting lines of the central trench, I, II, III, IV, V, I, making the trench 5 feet wide and of the length required for the number of guns (= No. of guns × 45'—10'); commencing then at a point A, 7' 6" to the left of I and in the rear cutting line, this party lays out the line a, b, c, d, e, etc., ... m, n, o, as indicated, the direction n, o, leading to the parallel.
The second party, beginning at A, lays out A, B, C, communicating with the parallel, and then the inner cutting line of the ditch D, E, F, G, H, I, allowing for a thickness of parapet of 30 feet and an ultimate width of ditch of 12 feet (D, E, and H, I).
Two parties should trace the battery in 25 minutes, one party in 45 minutes.
49. Constructing the Central Passage and Splinter Proofs.—The first relief of working party for the central passage is posted and commences work at once ([Pl. V], Figs. 47-48). Each man’s task is 5 feet in length and 4 feet in depth (giving 100 cubic feet). It may be completed in 4 hours, and should be in 6 at most.
The second relief ([Pl. V], Figs. 49-52) excavates the cartridge recesses, trims up the work done by the first relief, lowers any earth that stands too high, revets the slopes of the gun portions, puts in frames and sheeting when needed in the splinter-proofs, places the bearing planks and balks of the latter, which should be at least 9 inches thick and 9 feet long, except over the cartridge recesses, where they are 12 feet, and when possible deepens the central passage under the splinter-proofs to 5' 6" for a width of 2 feet to form a seat for the men. It also places one or two planks along the passage to serve as a bench for shells. The latter part of this work can be done by daylight. The parapet formed by this excavation is about 2 feet high. This is so masked or so inconspicuous as not to draw upon itself the artillery fire of the defence. The construction of the battery will be continued usually on the following night.
50. Construction of the Battery (Pls. V and VI, Figs. 53, 55, 60, 67).—Two reliefs are required for this. The first relief receives its tools and arrives upon the ground at dusk. It is divided into four parties, one for the front ditch, one for the gun portions, one for the rear trench, and a reserve of ten per cent for substitutes and casualties. They are posted and supervised by the engineer officer, n. c. os., and sappers as described in paragraph 16, ante.
The Front-ditch Party.—Each digger is assigned a task 5' wide, 6' long, and 3' 6" deep. He throws the earth as far into the parapet as he can. The shovellers, one to each two diggers, are posted 12 feet from the cutting line of the ditch. They pass the earth back toward the interior crest and the traverse, keeping the top surface nearly level.
The gun-portion party is divided up equally among the gun portions, each digger is allotted a task 4' wide, 7' 6" long, and 3' 6" deep. The gabions around the gun portion are placed by the shovellers under the direction of the engineer soldiers, a short one being placed at the throat of the embrasure. The shovellers spread and level the earth thrown out by the gun-portion parties and the rear-trench party. They work in connection with the other shovellers to give to the traverses and parapet near the interior crest the proper shape.
The Rear-trench Party.—This party excavates to a width of 7' 6" the rear trench and the communications with the parallel or approach. Each digger has a task 4' wide, 7' 6" long, and 3' 6" deep. The two directly in rear of each gun portion throw the earth to the rear, the others throw it to the front, leaving a berm of 4' 6" at the rear of the traverse. The men of the reserve who are not otherwise occupied fill sand-bags from the earth thrown to the rear, and cut a ramp 8 feet wide and not steeper than ¼, in rear of each gun-portion, when needed. It is essential that the excavation of the gun-portion be finished by the first relief, so that the platforms may be laid by the second relief in time to allow the guns to be placed before daylight.
The first relief leaves in the battery the tools required by the second and carries the rest back to the depot.