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MINUTES OF PKOCEEDINGS OF 
than J-inclq it is evident that all the layers of the india-rubber band 
will also be in a state of similar tension to that of the band in the 
first case, though induced in a different manner. In this second 
case the expansion of the interior diameter of band and its state of 
tension is induced by the resistance of the paper tube to compression 
beyond a certain amount, and by the inability of the band in conse¬ 
quence, to return to its normal state. 
The expansion of the band in this case represents the expansion 
by heat of the rings in actual manufacture, and their being subse¬ 
quently prevented from re-assuming their original diameter, while in 
the first case the expansion of the paper roll with the ring upon it, is 
similar to the mode in which tension is given to the outer layers in the 
bronze steel gun. 
It must be confessed, however, that in one case the power of the 
paper roll, or inner layer itself, to resist expansion from either is 
weakened, while in the other case (that of the ringed gun) it is on the 
contrary increased. 
Is this defect counterbalanced by the different layers in the bronze 
steel representing infinitely thin hoops in different states of tension ?* 
This brings us to the next condition, viz.,— 
2 .—' u The successive strata of metal in the bronze steel gun from 
within outwards, possess a relatively diminishing strength, hardness, 
and elasticity, which is precisely what is demanded by the objective; at 
the bore, namely, the metal is strongest, hardest, and most elastic, and 
as these properties diminish the toughness of the metal increases. 
The elasticity of the bore and the toughness of the outer surface are 
greater than in steel/ 5 
Remark.— i{ The small malleability of steel bronze at the bore reduces 
the power of resistance (mechanical fracturing force) to about -g-V- of 
Krupp steel the toughness of the outer strata cannot compensate 
for the hardness of the inner strata. 55 
* Each tube or hoop, when of a definite thickness taken by itself, has an element of 
weakness, its inner circumference is more stretched and strained than its outer circum¬ 
ference. Absolute perfection would necessitate infinitely their hoops, and practically the 
thinner the layers the greater the strength, provided the mechanical difficulties in con¬ 
structing, and more especially in applying a great number of their strata with the proper 
tension do not outweigh their advantages.—“ Holley on Ordnance,” p. 245. 
This disadvantage, as well as that of want of continuity, are got over in the bronze steel 
gun. Defects fully explained by Dr. Longridge, in “ Construction of Artillery,” and 
which he endeavonred to surmount by winding steel wire round an inner tube, the several 
layers being put on with different degrees of tensions. The system of construction is 
now being tried in France with much success, it is said, in the case of an experimental 
field gun. 
t The total mechanical force necessary to break a bar, depends principally upon the 
expansion at the limit of fracture, (vide fig. p. 16), and the tougher the gun metal the 
safer the gun; but on this point his critic observes, that the Krupp steel with 21*4 per 
cent, extension (vide Table A) is tougher than the bronze steel of General Von Uchatius 
with 2.5 per cent.—“ Unfortunately,” he says, “ the Table (A) does not go far beyond the 
“ limits of elasticity, and it is not easy, therefore, to arrive at the total mechanical force 
“necessary for rupture. Experiments carried on by Kirkaldy, in London, show that this 
“ force is with Krupp steel, 142’5k per cm., as compared to 9‘88k in the case of common 
“ bronze. We may therefore say, that with Krupp steel and bronze steel, these forces 
“would be 171’2k per cm. and20 , 31k per cm. respectively,” i.e. 8‘5 : 1. 
