( 20 )
But there is another construction of gun, which admits of the theoretical calculations being much more nearly followed. I allude to the system of coiling flat steel wire, or ribbon, around the tube, laying on these coils cold, and under predetermined tensions. There are many hopeful features about this system.
Steel in the form of wire, or ribbon, is in a condition of very great tensile strength. The section of the material being so small, it is very unlikely there can be any concealed flaws. Moreover, if there are any, it is very unlikely that in the successive layers of ribbon, such flaws would be aggregated in the same part of the winding, and thus there is hardly any chance of a considerable local weakness. Further, if there be a flaw it cannot go on spreading, as it may do through solid metal, but must be confined to its own layer. These are all-important elements in favour of the use of steel wire or ribbon, and I believe if we had simply to consider the question of fortifying a cylinder, to resist circumferential strain and nothing else, wire might unhesitatingly be adopted. In these days of machine guns, and of quick-firing guns, however, there is always a chance that a "Big Gun" may be struck by one of their bullets, and it might well be that a bullet, which was too small to inflict serious injury upon a gun reinforced by solid steel hoops, would cut the wire coils to pieces, and would thus temporarily render the Big Gun unserviceable. This chance renders it necessary to enclose the wire, in some kind of jacket, that shall be sufficient to afford protection against bullets from such artillery. Moreover, in a breech-loading gun, the question of longitudinal strength, and the due connection with the trunnions has to be taken into account, and hence further difficulties arise with the wire construction. These difficulties have, however, in a great measure, been already successfully grappled with in England, and there are now some four or five guns and howitzers under experiment, the largest being a gun of 10¼ inches bore, having a length of about 29 calibres.
So far the results have been promising, at least in England. The French have found the means they provided for giving
