218 
MINUTES OF PROCEEDINGS OF 
barrels now made of a better iron than that previously used are almost free 
from flaws, and those that occur are very small.* * The fact is, the barrels 
have been abused, not only for their own imperfections, but also for the 
failures of the vent pieces. 
Several important modifications in manufacture, which will both decrease 
the cost and increase the endurance of the gun, have lately been proposed 
in the Eoyal Gun factories, by Mr Eraser, the manager and assistant- 
inspector of machinery. The chief modifications are a reduction in the 
number of coils; the use of a cheaper iron for the outer coils; the 
shrinking on of the outer coils and trunnion piece together; and an 
improved arrangement of shoulders -and recesses to prevent separation 
of the parts. The cost of material is thus reduced, a less quantity of 
metal is required, much time is saved in the manufacture, and as the 
parts are large and few in number, and better disposed for mutual support, 
the endurance will, in all probability, be increased. 
Mr Whitworth is a strong advocate of steel for all parts of a built-up 
gun.f His method of building up differs from that of Sir W. Arm¬ 
strong :—“ The tube of the gun is made taper, being in the 5J-inch bore 
gun one inch larger in diameter at the breech end than at the muzzle end; 
then a series of hoops are made, which are screwed together so as to form 
another tube, that is put on by hydraulic pressure,J each layer is put on a 
little tighter than the succeeding one.*” Mr Whitworth asserts that pres¬ 
sure is more certain than shrinking; the latter can, however, be done with 
sufficient accuracy. Captain Blakely also is, I believe, a; strong advocate of 
steel for both inner tube and outer rings, although he has also employed 
both cast and wrought-iron for portions of some of his guns. 
The method of closing the bore of a built-up gun is an important ques¬ 
tion. The inner tubes of some of the large M.L. ordnance lately constructed 
in the Eoyal Gun Factories, as well as those of some of Blakely's guns have 
what are termed closed ends, that is, the tube is not bored through at the 
bottom; the solid end of the tube in the service guns is supported by a 
cascable screwed into the breech-piece, and in some of them also by a 
shoulder in the breech-piece. Sir W. Armstrong, Mr Whitworth, and 
Major Palliser use open tubes, and close them by a plug of wrought-iron 
or copper. The cascable in the Whitworth guns is not like Armstrong's, 
cylindrical in form, but is shaped into two or more (screwed) cylinders, 
their respective diameters increasing from bore to breech (see Plate). In 
closing the bore either of a M.L. or B.L. gun, one important principle 
should not be neglected, viz. that as the gas exerts an equal force in every 
direction, the thickness of metal should be as great, or nearly so, behind as 
only derive greater strength from the welds lying transversely to the bore (as in a coiled tube), but 
we also attain greater durability, because when they run in the direction of the bore, the scour of 
the gas eats into them, and causes fissures in the most dangerous direction, while in the other case 
the scour crosses the lines of the welds, and produces very little corroding effect.”—Report on 
Ordnance, p, 134. 
* A tube of coiled iron in a Palliser gun, after several hundred rounds, shewed no sign of a flaw 
in a weld. 
f The trunnion pieces of his experimental guns are of wrought-iron. 
j Mr Whitworth’s Evidence. Report on Ordnance, p. 126. 
