242 Mr. Mallet on the Physical Conditions 



21. — Sted as a material for Cannon, in relation to its Working Properties. 



189. In addition to what has preceded respecting the resisting powers of 

 steel, both absolute and comparative, a few remarks are required as to its other 

 properties in relation to our subject. 



Cast-steel is that alone capable of becoming a material for ordnance, as the 

 thin bars, alone capable of being obtained by cementation, are, owing to the 

 difficulty of welding steel into larger masses, unfit for the large scantlings 

 demanded. An apparent exception to this occurs in the Stahleisen of Styria 

 and other parts of eastern Europe, which is obtained by a modified process of 

 puddling, direct from the pig-iron, and hence at once in large masses. This 

 steel was first brought prominently into notice for large constructions, by Herr 

 Ignaz V. Mitis, who, in the year 1828, constructed a suspension bridge at Vienna 

 of 334 feet span, the chains of which are formed of it. He states (" Beschreib 

 V. die Carlsbrucke, der Ersten Stahls Kettenbrucke, in Wein:" 8vo, Wein, 1827 ) 

 that this steel does not begin to stretch under 47,125 lbs. = 21 tons per square 

 inch, and that he proved the chains of his bridge to 25 tons per inch of section. 



This so-called steel, however, offers no inducement to attempt its use for 

 guns ; for, although low in price, obtainable in large masses without welding, 

 and named steel correctly, in so far as it possesses the property of being 

 " hardened" by sudden cooling, it is in fact, but a fine form of harsh strong 

 iron, almost every example of which possesses more or less the same property 

 of being thus hardened ; for the finest steel passes by insensible gradations into 

 the softest and most ductile wrought-iron, which receives little, if any, appre- 

 ciable change in hardness from sudden cooling. 



The resistance to tension of the Styrian steel is little more than double that 

 of average wrought-iron, and its extension far less. Its coefficient 7", is, there- 

 fore, much below that of good soft wrought-iron. 



190. Cast-steel, however, being in the course of its manufacture fused, 

 although this is usually done in small and separate crucibles, is found capable, by 

 dexterous management, of being cast into very large masses of nearly perfect 

 solidity, which may be afterwards forged out under the tilt or steam-hammer into 

 longer pieces of smaller diameter, with much facility, cast-steel being at a parti- 

 cular temperature extremely malleable. (Note P. ) This is understood to be the 



