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MINUTES OF PROCEEDINGS OF 
too great a diminution of the calibre would injuriously diminish the 
efficiency of the shell. This is one of the points at which the principles 
of the two classes are interdependent. 
In determining the calibre to be given to a gun to throw a projectile 
of a certain weight, we must, therefore, balance these advantages and 
disadvantages, and determine the diameter of bore we choose by an 
argument of the following nature. 
The diameter of the bore should be reduced as much as is consistent 
with the capacity of the gun to burn sufficient powder to give the pro¬ 
jectile such a remaining velocity as may be considered necessary at its 
extreme range, and consistent with not impairing the efficiency of the 
shell or shrapnel. 
Very considerable initial velocity may be given even to a projectile of 
small calibre in a breech-loading system, by a slight chambering of the 
gun at the seat of the cartridge, so as to diminish the length of the 
cartridge and cause the powder to burn quicker, in which case a con¬ 
siderable flattening of the trajectory would ensue. It has been stated 
lately that the French have constructed a field gun which has thrown 
its shot with the extraordinary initial velocity of 2000 ft. per second. 
If this is true, the result has probably been obtained by the chambering 
which they have employed. It is a subject worthy of consideration 
whether any device can be discovered to enable a chamber to be used 
with muzzle-loading ordnance. 
Another consideration to be borne in mind is, that as with a smaller 
calibre a lower initial velocity is required to give an equal remaining 
velocity, the shock of recoil will be less, and therefore the weight of 
gun and carriage may be reduced—which is a subject of importance in 
connection with the mobility of field artillery. 
The increased strain caused by an increase of twist, will not be great 
enough within the practical limits of the decrease of bore for it to be 
necessary to take it into consideration. 
All that has been said hitherto is applicable to all systems of rifling. 
We will now endeavour to discover what are the principles that should 
guide us in choosing a system for adoption. 
All the systems at present proposed may be divided into four 
classes. 
(1) Breech or muzzle-loading systems, with hard mechanically- 
fitting projectiles. 
(2) Breech-loading systems, with projectiles slightly larger than the 
bore, and covered with a soft metal coating, which is forced into the 
grooves as the projectile is driven through the bore by the force of the 
explosion of the powder; 
(8) Breech or muzzle-loading systems, with hard projectiles haring 
a soft expanding base or coating; 
(4) Breech or muzzle-loading systems, having hard projectiles With 
soft projecting studs. 
It is found that all these classes of systems give practically equal 
results US regards accuracy of fire, if fired under suitable Conditions of 
charge^ angle of twist of rifling, &c.; so we must look to other points to 
enable us to make our choice between them. 
