HC Deb 13 September 1886 vol 309 cc176-7
SIR HENRY TYLER (Great Yarmouth)

asked the Secretary of State for War, When he will be prepared to state on the authority of the Ordnance Special Committee with Associated Members, the factor of safety as between the calculated bursting strain on the one hand, and the calculated strain with service charges on the other hand, of the guns that burst on board the three of Her Majesty's Ships Active, Thunderer, and Collingwood; and, when he expects to be able to quote the opinion of the same Committee as to whether "jamming" of the shot in the increasing twist of the rifling would not be sufficient to account for each of those failures?

THE SECRETARY OF STATE (Mr. W. H. SMITH) (Strand, Westminster)

With reference to the factor of safety in the Active's and the Collingwood's guns, it is stated in the Ordnance Committee's Report of 1883 that the factor of safety between the service pressure and the bursting pressure should be four—that is, that the maximum working pressure should be one-fourth of the bursting pressure, arrived at by a formula in use at that date, and the service charges of these two guns were regulated by the recommendation of the same Committee to give this factor. The factor of safety on the Thunderer's gun has not been gone into by the Ordnance Committee; but, calculated on the same basis as the factor just given, is also four. It is to be noted that the method of calculation referred to by the hon. and gallant Member is now obsolete, and that all recent calculations of strength bring out the relation between the service pressures and the pressure which would strain the gun beyond its limit of elasticity. With reference to the second portion of the hon. and gallant Member's Question, the accident to the Active's gun was referred to a special Committee, who reported that they were clear that the burst did not arise from jamming; and the specially-constituted. Ordnance Committee subsequently concurred in that view. The specially-constituted Ordnance Committee have also assigned causes entirely unconnected with jamming for the accident to the Coiling wood's gun. The case of the Thunderer's gun was not laid before the specially-constituted Ordnance Committee; but it formed the subject of an inquiry conducted by two special Committees, the Reports of which were presented to both Houses of Parliament. Both Committees agreed in attributing the accident to a cause quite distinct from jamming. It should be noted that in the Active's and the Collingwood's guns the forward portion of the bore where the burst occurred was rifled with the uniform twist, and, therefore, the accidents could not be attributable to the jamming of the shots in the increasing twist.