THE EIGHTY-TON GUN, OR WOOLWICH INFANT. 243 
this piece is constructed on the Fraser system. The steel tube 
is roughly bored out before the gun is built up and finished, and 
rifled afterwards. The total weight of the iron forgings and other 
separate parts to be thus united is given by Major Maitland, 
the Assistant-Superintendent of the Grun Factories, in a paper 
sent to the E.A. Institution, as 164 tons 16 cwt. when in the 
rough state. 
In the manner just described a gun can be made, so it is 
believed, as strongly as is possible on any system. It is difficult 
to speak positively, because steel guns are frequently found to 
be very strong, and when tested to destruction they have exhi- 
bited greater durability than was thought could have been 
shown by any other material. Possible or probable durability 
of a high character, however, is not at all so desirable an 
element to exist in a gun as the positive assurance of some 
standard, even though a much lower one. This is what may be 
claimed for wrought-iron guns compared with steel. The 
former are very reliable, and possess very high resisting powers; 
the latter may possess extraordinary powers, but may occasion- 
ally burst unexpectedly, and when they do so the fragments 
fly violently in all directions ; whereas should the wrought-iron 
gun give way, it does so gradually, and so no danger is to be 
anticipated. The conditions which principally have to be con- 
sidered, at all events with the Woolwich guns, are those under 
which the bore of the gun may best perform the work required 
of it, and resist the effects of wear and tear caused by the 
erosion of the gas, our guns having worn out in many instances 
very rapidly. Matters have been improved by the introduction 
of tight-fitting copper gas-checks, which fix on to the base of the 
projectiles, and prevent the gas from escaping past their sides, 
and so scoring the bore of the gun as well as wasting available 
power. It has been considered desirable, however, that under 
any circumstances the pressure of gas in the bore of the gun 
should not be allowed greatly to exceed about 25 tons per 
square inch. The principal problem involved in the whole 
question may be thus stated. How are we to discharge the 
projectile with the desired velocity without bringing on the 
bore of the gun a pressure exceeding about 25 tons ? The size 
of the bore of the gun affects the question, because much 
depends on the space it allows the charge to occupy. A larger 
bore admits of a shorter cartridge, and brings the powder into a 
more compact mass through which the flame of explosion passes 
more easily, and so generates the gas more rapidly. Connected 
with this is the question of giving guns enlarged chambers, so 
as to burn the powder in a more favourable manner than the 
desired size of bore would allow. Sir J. Whitworth, in 1872, 
had great success with a breech-loading gun with an enlarged 
