MILITARY ENGINEERING 3 6 9 



introduced under the name of the " Railophone " for effecting telephonic communication 

 with moving railway trains. It is based on inventions by Von Kramer and Gisbert 

 Kapp. (J. A. FLEMING.) 



MILITARY ENGINEERING 



i. HEAVY FIELD AND SIEGE ORDNANCE EQUIPMENTS 1 



Since the introduction of quick-firing field guns, it was to. be foreseen that inventors 

 would apply the same principles of construction to equipments of heavy field and siege 

 artillery. In fact there now exist several equipments which have common characteris- 

 tics, i. e. the long recoil of the gun on the mounting, the reduction if not suppression 

 of movement of the sights, and the simplification of loading and laying. 



Heavy Field Armaments. The size and weight of heavy field equipments have not 

 been limited to a train in which the gun travels on its firing carriage attached to a limber, 

 but have developed to such an extent that a train may necessarily be comprised of more 

 than one carriage, the gun being dismounted for travelling and not merely drawn further 

 back on the trail for the balance of the load. With a gun so much heavier and more 

 powerful the application of the principle of the long recoil is faced with some difficulty 

 the length of the recoil when the gun is in the neighbourhood of the horizontal being 

 necessarily very considerable in order to obtain the desired stability. With howitzers 

 also the application of the principles which have given such a happy solution for the 

 field gun is full of serious difficulties, of which the chief is the necessity of obtaining angles 

 of elevation of 40 to 45. The height of the trunnions is limited by considerations of 

 stability and weight of equipment, and with this limitation a long recoil at high angles 

 of elevation would cause the breech to foul the ground. 



Two solutions present themselves: (i) to arrange trunnions at the rear end of the 

 cradle, as near the breech of the piece as possible; (2) to arrange a variable recoil. 

 Krupp favours the first, with springs compensating for preponderance; such springs, 

 however, cause uncertainty and unevenness in laying for elevation, as they vary in 

 tension. Ehrhardt favours the second. Cockerill has tried to combine the advantages 

 of both but not quite satisfactorily. Schneider, while constructing with the variable 

 recoil, has made an original application of the rear trunnions. 



Schneider 15 cm. Gun. With this carriage the expression "variable recoil" is not exactly 

 accurate. In reality the buffer is disposed in a manner to give a long recoil of a fixed length 

 at all angles between maximum depression and 14 elevation; and a reduced recoil, also of 

 fixed length, at all angles between 20 elevation and maximum elevation. Between 14 and 

 20 elevation the recoil is variable. Two steel valve keys are fixed to the buffer cylinder and 

 engaged in slots in the piston. Their height varies, modifying at each instant the holes 

 for the passage of the liquid. Their breadth being constant but less than that of the slots 

 in the piston allows of a slight rotary movement to the piston. At high angles of elevation 

 the liquid escapes through the slots only and the recoil is reduced. But when the angle 

 decreases, holes in the head of the piston open, and the length of recoil increases. To obtain 

 this effect, on the piston rod and against the piston itself is mounted a disc, with slots of 

 exactly the same breadth as the valve keys, so that the disc cannot turn. There are holes 

 in this disc, which according to the position of the piston, either do not correspond with the 

 holes in the piston, so producing a reduced recoil; or partially correspond, with intermediate 

 variable recoils; or entirely correspond, with a long recoil. The position of the piston is 

 controlled through a rack and a toothed sector on a lever, the lever being worked by a bar 

 actuated by a roller moving in two arcs of different radii concentric with the trunnions and 

 connected to one another. For travelling the train consists of two carriages; the gun is 

 raised out of its firing carriage by a screw and wound off by means of a windlass on to a 

 four-wheeled block carriage; the mounting with cradle complete is attached 'to a limber, 

 forming the first carriage of the train, of which the block carriage forms the second. 



Schneider 120 mm. Howitzer.- There are three models of howitzers built by Schneider: 

 light (105 mm.), medium (120 mm.) and heavy (150 mm.), of which the 120 mm. may be 

 taken as typical. The piece rests in a saddle which recoils with it; the buffer cylinder and 

 recuperator form part of the saddle. The buffer allows of a variable recoil, regulated by 

 variation of the holes for the passage of the liquid. The piston is attached to the cradle and 

 the cylinder is pulled off it on recoil. The recuperator takes the form of a cylinder con- 

 nected with air reservoirs, the air being compressed during recoil and, reasserting itself, 



1 See E. B. xx, 223 et seq. 



