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MINUTES OF PROCEEDINGS OF 
tube with coiled iron exterior, but the quality of the steel could not 
at that time be depended on, and the guns which were introduced into 
the service in 1858-9, were therefore made entirely of coiled wrought- 
iron, this construction being adhered to for the greater number of our 
B.L. guns. 
We have therefore had the. experience of about twelve years in judg¬ 
ing of the suitability of wrought-iron as a material for field guns, and, 
as far as safety from rupture is concerned, it may be stated to be 
absolutely perfect, for no gun of this nature has ever burst explosively 
on service, or from fair usage. 
However, for some time past, the plan of making the whole gun of 
wrought-iron has to a great extent been abandoned, for, though per¬ 
fectly safe from any danger of bursting, the imperfections inherent in 
this material, and the great difficulty experienced in making the inner 
barrel sufficiently sound, satisfactorily to resist the corrosive action of 
the powder gas, have led to the adoption of steel for the core, coils of 
iron being shrunk on the outside to strengthen and support it. We 
have thus, as far as the inner barrel is concerned, reverted to Sir W. 
Armstrong's original construction, as exemplified in his first experi¬ 
mental gun (the 6-pr.) and we are enabled to do so from the 
improvement in the manufacture of steel since 1858. The advantages 
of the change are obvious : defects in the material which are of no 
consequence whatever in the outer portions of a gun, are very detri¬ 
mental in the surface of the bore, where the gas acts directly on them 
and eats them out rapidly, particularly if they occur in rear of the 
trunnions. Steel therefore, being entirely free from such defects, has 
been adopted for the tubes of guns in order to obtain a hard and sound 
surface capable of resisting the friction of the shot and the action of the 
gas, but it is found even then that the tube is the more perishable 
portion of our heavy guns, and that it sometimes fails while the iron 
exterior remains intact, thus affording conclusive evidence of the 
superiority of good wrought-iron in resisting the dynamical strains to 
which a gun is subjected on firing, and the danger of trusting too much 
to the results obtained when specimens of metals are tested by statical 
strains only. 
Wrought-iron lined with steel having then been proved, by a series 
of costly experiments unequalled in the annals of artillery, to be the best 
construction for our so-called iron guns of the service, let us now see 
what advantages or disadvantages would result from the substitution of 
bronze in its place for field guns. 
The following are the principal points of comparison between the 
two metals, iron and bronze, viz.:— 
1. As regards security from bursting. 
2. Qualifications for the inner barrel, i.e . (a) hardness, (b) soundness, 
and (c) capability of resisting expansion. 
3. Deterioration from exposure. 
4. Economy. 
5. Facility of manufacture. 
6. Facility for changing the system, i.e. facility of remanufacture 
and value of old metal. 
