THE ROYAL ARTILLERY INSTITUTION. 
411 
breech end of the tube was split right through. After this the gun fired 
41 rounds, and then at length, at the 1049th round, the A and B tubes 
were bodily forced about an inch forward. This closed the vent, and conse¬ 
quently put an end to the trial. 
The result was deemed most satisfactory, not only because the steel tube 
failed so gradually, but because the great strength of the outer fabric—the 
point at issue—was proved beyond all doubt by the gun actually firing 
forty-one rounds after the tube was split through, and yet remaining sound 
exteriorly. 
Both guns behaved so exceedingly well under trial, that the authori¬ 
ties were left in the pleasant dilemma of not knowing w T hich pattern to 
choose :—-No. 332, with a steel tube two inches thick, and reinforced with two 
double coils, survived the trying ordeal. No. 368, with a steel tube three 
inches thick, and reinforced with one massive triple coil, did not it is true 
complete the test, but it refused to yield although its tube was split. 
With respect to the precise pattern for future construction, it would 
perhaps have been the safest course to have continued firing No. 332 gun, 
and then if it did not blow its breech off (its tube being so thin), or burst 
explosively without giving ample warning, to adopt it as the pattern of all 
the heavier natures. The authorities, however, have decided on constructing 
7-inch and 8-inch guns as before, on the No. 368 type, but to make 9-inch 
guns and upwards on the No. 332 type.* 
Present state of the question. 
The question then stands thus :—Up to April, 1867, all our heavy guns 
were made on the original construction, like the 9-inch gun, Mark I., and 
from that date up to the present nearly all have been made like the 9-inch 
gun No. 368, or Mark III.— i.e . consisting only of four parts, viz. steel 
tube, cascable, B tube, and breech coil—and 7-inch and 8-inch guns will 
still be made in the same way. Of all these, the 9-inch gun is the most 
important; it is very powerful for its weight, and has been made in con¬ 
siderable numbers; it is therefore taken as a type of the most common 
form of the present construction, and its manufacture will now be described 
in detail. 
The alteration in future manufacture for 9-inch guns simply consists in 
having a thinner steel tube and two coils on the breech (see Mark TV.) 
instead of one triple one; or perhaps the difference in construction will be 
more readily remembered by using the familiar illustration, and saying that 
in the former instance the steel tube is enveloped in “jacket and trousers,” 
whilst in the latter it is thinner, and has “jacket, waistcoat, and trousers.” 
The higher natures are made in the same way, but have a “belt” in 
addition. 
# This pattern costs about the same as the other, the extra expense of making two breech coils 
being compensated for by the lighter steel barrel. Good reasons for preferring this construction 
for heavy guns would be that the inner coil can be made of twice rolled (i.e. superior) iron, and 
with greater perfection, and also that the thinner the tube the more will it be compressed 
by the shrinking, and strengthened accordingly. 
