For infantry: 1 N.C.O., 4 men, 2 mules, per gun. _Ammunition._--No details have been settled as to the amount or method of carrying. TACTICAL.--No official instructions for the tactical handling of machine guns have yet been issued. JAPAN GUN.--The Japanese have adopted the Hotchkiss,[68] the barrel of which is air-cooled, having seven radiating gills on the breech to absorb the heat. The bore is ·256, being the same as the rifle; the weight is 70 lb. It is regulated to fire at a maximum rate of 600 rounds a minute. It is loaded by brass clips containing 30 cartridges inserted into the left side of the gun. The empties are ejected on the right side. The gun is sighted up to 2,187 yards, with a tangent sight, and is mounted on a tripod weighing 40 lb., which has an all-round traverse, and can be adjusted to fire from two heights. Shields were used in the late war, but were discarded on account of the weight. It is probable that detachable shields, large enough to cover the detachment, will in future be issued with machine guns for use as the situation requires. [Illustration: DIAGRAM VI _Diagram of Japanese Machine Gun--Tripod Mount._ _a-b Front and Rear Sights._ _A Piston rod._ _m Gas Vent._ _e Gas chamber._ _d Regulating nut._ _e Strong spiral spring._ _s Feed Slot._ _R Radiator._] The Japanese machine gun is of home design and manufacture, and belongs to that class in which the mechanism is actuated by the action of gas pressure operating upon a plunger or piston and not by the direct force of recoil as in the Maxim. It uses the same ammunition as the infantry rifle (murata calibre ·256), and is rated as firing 600 rounds a minute. Two forms of mountings are employed, the tripod and the wheeled; the former for fortress use, and the latter for mobile troops. Referring to the plate, a gas vent _m_ communicates with a gas chamber _c_ attached laterally to the barrel. The pressure in the gas chamber is regulated, within limits, by the nut _d_, which varies the capacity of the chamber. The piston-rod _A_ is acted upon by the gas pressure at its forward end, and is driven to the rear against a strong spiral spring _o_, which moves the piston end forward after the gas pressure has ceased to act. The reciprocating motion of the piston-rod actuates the mechanism, which is entirely enclosed in the housing, and performs the various operations of feeding, firing, and ejecting through a suitable train of gearing. Cooling is effected by the radiator _R_, a circumferentially grooved mass of metal attached to the barrel. The cartridges are mounted on a strip of sheet brass from which clips are punched and bent round the cartridges to hold them in position. A series of holes along the edges of the brass strip engage the teeth of pinions which feed the strip forward as the piston _A_ moves backward and forward. The cartridges are fired from their clips by fingers, and drop into position when the bolt