involved in the Construction of Artillery. 169 



facilitating the preservation of that moderate temperature in the blast furnace, 

 upon which the production of the desired sort of iron depends. 



64. But the working of a small blast furnace, at a low temperature, and in 

 the method above described, produces necessarily a small daily yield of pig-iron 

 — it, therefore, will not pay ; and hence will not be adopted by any maker in 

 Great Britain, unless insured a proportionally remunerative price for his manu- 

 facture of a special pig-iron, destined and well fitted for the manufacture of 

 our national ordnance. If such an inducement be given, makers may soon be 

 found to produce pig-iron, better fitted for gun-founding than any foreign iron. 



65. It is a mistake to suppose that the foreign charcoal cast-irons have a 

 greater tenacity generally than our British "makes;" the reverse is the fact, and 

 equally so with wrought-irons. In proof of this I may quote the results of a most 

 carefully conducted and extensive series of experiments made under the direc- 

 tion of the late Mr. Tierney Clarke, C. E., with reference to the relative 

 strengths of Hungarian and Austrian cast-irons as compared with British ; the 

 former were proposed being used in certain parts of the suspension bridge 

 across the Danube at Pesth, in Hungary, exposed to transverse strain. 



General Results of Experiments on Hungarian Cast-iron at Pesth. 



Transverse strain, reduced to bars of 3 feet bearing, and 1 inch square. 



Count Andrasi's Iron, Dernij, 821-515 lbs. 



Hoffman, Brothers, Madersbach, 651 '996 „ 



Concordial Works, Sebok, T 675-655 „ 



Pesth Foundry, 813-021 „ 



Baron Rothschild, Styrian, 964-080 „ 



General average, , 785-253 lbs. 



Load in middle — All Cold- Blast Iron — Banks' experiments, quoted by Barlow, p. 221, gave a 

 mean of 844 lbs., and were Cold-Blast, agreeing very nearly with Tredgold's forStaffordshire'Cast- 

 Irons, also Cold-Blast. 



To these might be added sufficient proofs that, generally, the European cast- 

 irons made with charcoal, are not as strong (taking all the conditions which 

 the word embraces) as the best makes of British cast-iron. 



66. Again, as respects wrought-iron, if the numerous tables of experimental 

 strength, published by Karsten, Vicat, Le Blanc, Dulean, and others, be 

 examined, it will be at once seen that few continental "makes" of iron (even 

 charcoal iron) equal in strength our best British irons. As regards the special 



