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is tested by means of samples both as to its chemical and 

 mechanical condition. It is thereupon run into a ladle and from 

 that ladle into ingot moulds, and all we have to do afterwards 

 is to give it the particular form or shape required for our pur- 

 pose. It is therefore nothing more than natural that a material 

 so produced should be much more uniform and trustworthy than 

 the iron of former days. There is, however, still a prejudice 

 I cannot call it by any other name in the minds of many of the 

 users of these materials, because the steel of former days was 

 of an uncertain nature, and occasionally gave way when least 

 expected. Professor Kennedy has sufficiently alluded to the 

 causes of this, and I have no doubt but that very shortly this 

 idea will be got rid of entirely, and steel will be used in lieu 

 of iron for a great many purposes to which it has as yet been 

 unapplied, and that it will be trusted to a higher limit of its 

 strength than has hitherto been allowed either by the Board of 

 Trade or by the insurance companies. The advantages of steel 

 as a material to be used in architecture, I would consider to be 

 the following : For purposes where boldness and grandeur of 

 outline are essential no material can rival steel ; when we want 

 to bridge a third of a mile in span, or to construct a roof or 

 dome of enormous size, there is no material that can serve our 

 purpose like steel ; if the object is simply to get tensile strength, 

 without subjecting the material to cross strain, as is the case 

 in the chains of a suspension bridge, the use of steel wire enables 

 us to attain a limit of strength exceeding 100 tons per square 

 inch, or as much as five times the tensile strength of wrought 

 iron. The chains supporting the great American suspension 

 bridges across the Falls of Niagara and across the Hudson River 

 at New York are constructed of this material, and in the latter 

 case 120 tons per square inch is the breaking strength to which 

 the wires are tested before approval. If, instead of wire, links 

 or bars are used in the construction of bridges subject to con- 

 tinuous strain, the breaking strength (which is really optional, 

 being dependent upon the percentage of carbon admitted into 

 the material) may be conveniently fixed at from 40 to 50 tons 

 per square inch, or say twice the strength of wrought iron. 

 This same material lends itself best for rolling girders to span 

 large openings, and it will be readily conceived that, although 



