296 SECTION MECHANICS. 



what the general sense of owners accepts as necessary. The excellent 

 and careful details of construction exhibited by the London surveyors 

 is an illustration of their skill and faithfulness, but they are powerless 

 here. So also is the Board of Trade so long as foreign ships 

 are in the same condition, and owners and builders are satisfied with 

 the existing state of things. I should not be faithful to the profession 

 which I represent if I did not ask owners and builders whether it is 

 not high time that there was an alteration. 



In the matter of the material employed in shipbuilding I believe that 

 the iron in ordinary commercial use is better than is commonly sup- 

 posed. Still it is not sufficiently good or uniform in quality to come up 

 to the Admiralty tests, and tested iron is a special manufacture costing 

 from 4 to & a ton more than that known as ship plates. 



The fact that even this excess in cost is sometimes exceeded for 

 bottom plates in ships of war brings up the cost of first-class boiler plate 

 iron to near that at which excellent steel can be produced. 



Steel is now being made suitable for shipbuilding and boiler making 

 at a reasonable cost by both the Siemens' and the Bessemer processes. 

 There are two ships of war now building for the Admiralty at Pem- 

 broke, of Siemens' steel in all parts of the hull and in the boilers, and 

 nearly all the other ships building have certain portions made of a similar 

 material produced by the Bolton Steel Company by the Bessemer pro- 

 cess. The Admiralty is also using a more costly material produced 

 by Sir Joseph Whitworth for cylinder liners and for propeller shafts, 

 and the bodies of the Whitehead torpedoes are made of the same 

 material, viz., fluid compressed steel, having about fifty tons per square 

 inch of tensile strength and twenty per cent, of ductility, whereas the 

 steel preferred for ships and boilers has only twenty-eight or twenty- 

 nine tons of tensile strength, and from twenty per cent, to twenty-five 

 per cent, ductility. This latter material corresponds in quality with 

 that produced by the works of Messrs. Schneider and used by the 

 French Government. 



Ic is perhaps right that I should record that all vessels now building in 

 the Royal Navy have iron or steel frames. Wood is employed for that 

 purpose no longer. Timber is still largely used in some other national 

 navies, but I think unwisely. We have vessels as much as 220 feet 

 long, and with thirteen knots speed, having wood planking in two 



