Weight of caisson complete, without limber 1396 lbs. Weight of caisson and limber complete, without ammunition 2436 " Weight of caisson and limber } Light field-battery 4607½ " complete, with ammunition } Heavy field-battery 5080 " Length from end of pole to end of spare-wheel axle 24½ ft Distance between centres of axles 8 " [Illustration: FIG. 64_a_.] NOMENCLATURE. 1. Lunette. 2. Middle rail. 3. Front cross-bar. 4. Foot-board. 5. Pickaxe attachment, front. 6. Ammunition-chest keys and chains. 7. Brake-chain. 8. Side rail. 9. Spare pole. 10. Ammunition-chest. 11. Brake-lever. 12. Front ammunition-chest handles. 13 Pickaxe attachment, rear. 14. Axe and spade board-irons. 15. Middle rail. 16. Brake eye-strap. 17. Rear ammunition-chest handles. 18. Ammunition-chest keys and chains. 19. Spare-pole stirrup. 20. Spare-wheel axle-bolster. 21. Spare-wheel axle-washer. 22. Spare wheel. 23. Spare-wheel axle. 24. Toggle. The limber of the caisson has already been described. The caisson, Fig. 64_a_, consists of one wrought-steel tubular axle and two Archibald wheels (57¾ in.), same as for limbers, the caisson-body, and connecting parts, viz.: The =Middle rail= (central part of body formed of two angle-irons) receives the lunette in front and spare wheel in rear, and is attached to the axle by an understrap, and to the side-rails by front and rear cross-bars, with connections stiffened by brackets, and the strength at axle increased by middle-rail braces. The =Side-rails=, which are attached to the axle by understraps and joined to the middle rail by the front and rear cross-bars. The =Foot-board= is fastened to the middle and side rails with brackets to incline the surface of the board. =Floor-rods=, passing through middle and side rails, between rear chest and rear cross-bar. Two =Road-brakes= complete, and attachments for implements and spare parts. The lever road-brake now supplied is similar to the ordinary wagon-brake, and so arranged that each side may be operated separately. The shoe is applied in rear of the wheel, and the brake-lever stands upright inside the wheels, opposite the front side of the rear ammunition-chest. The caisson body carries two ammunition-chests same as for limber. ON THE CAISSON CAN BE CARRIED: =A Spare Wheel=, which fits upon an iron axle-arm attached to the rear end of the middle rail, or a spare pole. Two long-handled shovels. Two pickaxes } by suitable attachments underneath. One spare pole, } Two spades, } between chests. Two axes, } Four watering-buckets, canvas. One or two lanterns. Two paulins, on chests. One manœuvring-handspike, right side, along the side-rail.