FABRICATION OF ARTILLERY. 133 



pipe ; g, pot furnace ; //, chimney ; z, fire-bridge ; k, sole ; /, ash-hole , 

 VI m', stoke-holes ; n, flue ; o, conduit. 



The gun after casting is taken from the mould, and then is usually bored 

 and turned at the same time, if the boring machine, as is now generally the 

 case, is horizontal. When the boring is vertical, the turning is done after- 

 wards. Previous to boring and turning, however, a bolt of hammered 

 copper is screwed in where the touch-hole is to be. When the piece is 

 bored and turned, the trunnions are turned separately, the part between the 

 trunnions and the dolphins worked off with files and rasps, and finally the 

 vent bored out. Before it is used the piece is subjected to the most careful 

 proof. 



d. Casting Projectiles. Solid shot, case shot, and shells, are cast at 

 iron works from white forge-iron. Formerly iron moulds were used for 

 these, also ; but they had the effect of making the balls too hard on the sur- 

 face, whereby the bore of the gun was injured. At present, therefore, pro- 

 jectiles are cast in sand, in mould-boxes. 



The casting of solid balls is the most simple. The patterns for this purpose 

 are of brass^ very exactly turned, made in two halves, and fitting into each 

 other by a groove. One half has a pin screwed into it, which forms the 

 hole by which the metal is poured in at the casting. PL 39, fig. 31, shows 

 the manner of moulding. The mould (flask) consists of the mould boxes 

 (fig. 29 shows two such boxes, standing one upon the other), which are 

 secured together by key-bolts. In moulding, the grooved half of the pattern, 

 a, in this case a 24-pound ball, is set upon the mould-board 5 s, and the tap- 

 hole pin, c, screwed in ; then the mould-box is placed with its key-bolts in 

 the holes made for them, and the half ball moulded by the sand layer B ; the 

 mould is then turned over, the mould-board taken off, the second half-ball 

 set on, the second mould-box placed, and the mould made in the same way ; 

 then the mould is turned, the pin screwed out, the mould-box opened, and 

 both patterns taken out, when it is again closed, and is then ready for cast- 

 ing. Smaller balls, as 6-pound and case-shot, are moulded four or more in 

 one box. Fig. 30 shows one part of a mould-box for four 6-pound balls, and 

 fig. 29 the two boxes, one on the other. A is the upper box, B the lower 

 box ; a a are the patterns ; h, the jet hole, lying in the centre ; d d, the jet 

 channels, which are cut in when the mould is finished; cc are small pipes, 

 air-vents, to let the air pass out when the mould is filled ; e e, the key-bolts. 

 The mould of the hollow shot is more complicated, because the internal 

 cavity of these must be formed by a core, which remains in the mould dur- 

 ing the casting and is removed afterwards ; and because, also, for the larger, 

 a pair of ears must be cast in, for the shell-hooks to catch hold of in trans- 

 portation. Fig. 32 shows the two mould-boxes for a shell or bomb, with 

 the patterns belonging to them as placed for moulding. A is the lower 

 mould-box ; q, a plug, by means of which the fuse-hole is formed, and which 

 is replaced afterwards by the core-spindle ; a is the pattern, upon which are 

 a pair of ears, to form the sockets for those of the shell ; B is the upper 

 mould-box ; a, the pattern, with the jet-hole 6, and the air- vent c, for the 

 escape of the gas which is generated. For hollow shot it is preferable to 



ICONOGRAPHIC ENCYCLOPEDIA. VOL. III. 39 609 



