involved in the Construction of Artillery. 251 



210. A very large quantity of wrought iron is made in North America witli 

 charcoal and with anthracite, — a fuel almost as perfectly free from sulphur ; 

 but the following results of trials of ultimate strength, by the Commission of 

 the Franklin Institute, do not indicate that superiority, which has been so boldly 

 asserted in certain quarters in England, of foreign iron, " which has never been 

 exposed to the deteriorating influence of sulphur," over British " makes." 



Experiments ore the Relative Strength of American and other Wrought-Iron. 



Mean Breaking Weight 

 Make. per square inch, 



lbs. 



Missouri bars, 47909 



Slit rods for nails, .... 50000 



Tennessee 52099 



Salisbury, Con 58009 



Center Co., Pa 58400 



Lancaster Co., Pa 58661 



English bar iron, 59105 



Swedish bar, . . . ^ . . 58184 



Russian bar, 76069, low steel, in fact. 



Cast steel, 130681 



These remarks, with those of sect. 66, are sufficient to show that we need 

 not go out of England for wrought-iron for ordnance, any more than for cast- 

 iron, if we only take the requisite measures to make the supply of suitable 

 materials worth the iron-masters' attention. 



24. — Helation of Elasticity to the Crystalline Axis. 



211. Some experiments of Mr. Fairbairn's, on the relative ultimate resist- 

 ance to rupture of boiler-plates, when strained in the direction of their fibre, i. e. 

 in the direction in which they were rolled, and transversely to the same, have 

 induced him to come to the conclusion that there is little, if any, difference. 



If the iron of the plates be so very harsh, rigid, and of bad quality, as to 

 have no (fibre) longitudinal crystalline arrangement, but approach nearly to that 

 of a slab of cast-iron, — this may perhaps be nearly true, but in plates or bars 

 of good quality it is certainly erroneous. The few experiments (twenty in all) 

 upon which Mr. Fairbairn's conclusion rests, even will not warrant it, if one 

 result contrary to all the others, and so exceptional as to suggest the probability 



