=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. o^s., 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.