ON METALS FOR ORDNANCE. 103 



of malleable iron, — a candid admission on the part of one whose exertions in 

 that direction are so well known. 



Mr. Nasmyth then refers to the failure of cast-iron guns of recent con- 

 struction. This he attributes principally to two causes: first, to the use of 

 iron smelted aud cast by coal ; and secondly, to the modern method of 

 casting without a core. The superiority of Russian and Swedish guns, 

 proved by the late war, he ascribes to the use of iron prepared by ivood fuel ; 

 coal in all cases detracting from the tenacity of iron by contaminating it 

 with sulphur. For this reason, hot-blast iron, smelted by raw coal, is inferior 

 to cold blast, which is smelted by coke from which many of the impurities 

 of the coal have been driven off. He believes that the present method of 

 casting without a core causes the centre or last-cooled portion to be spongy 

 and deficient in density and strength. To secure the greatest density and 

 tenacity in the centre, the present mode must be reversed, and, — as, 

 according to his statement, has long been practised in Russia, Sweden and 

 the United States, — must be cooled from the centre outwards. Mr. Nasmyth 

 proposes that the core should consist of a malleable iron chamber, kept cool 

 by a current of air or by a stream of water. In this way he thinks we shall 

 obtain increased density of metal where it is most wanted, and he hopes fully 

 to prove the correctness of his views by the construction of a mortar of great 

 strength and range, now in progress. In conclusion, he points out the un- 

 fitness of the spherical form for a missile expected to reach its destination 

 with precision, on account of its susceptibility to slight disturbing causes. 

 He considers the Minie bullet, especially when axial rotation is imparted, to 

 possess all the conditions required to give efficiency to a projectile. 



In addition to the above, we may observe that most of Mr. Nasmyth 's ob- 

 jections to wrought iron apply also to steel : for although it can be cast 

 and run into moulds, and can afterwards be rendered malleable by the 

 strokes of a powerful hammer, with some degree of certainty ; yet, looking 

 at the results of the attempt to produce a 68-pounder gun, made by one 

 of the most distinguished steel manufacturers in Europe, Herr Krupp, of 

 Essen in Prussia, and taking into consideration the enormous cost, we may 

 conclude that this valuable material is not calculated to supplant cast iron in 

 the manufacture of ordnance. 



With regard to Mr. Nasmyth's opinion on the subject of casting with a 

 core, undoubtedly great advantages would result if it could be accomplished. 

 But in this process many obstacles have to be surmounted, arising from the 

 difficulty of regulating the rate of cooling on the exterior and interior sur- 

 faces, and from the obstacles in the way of boring after a core. This process 

 has often been tried in this country, but in practice has generally been found 

 unsuccessful. In America and in France it has also been attempted, but we 

 have yet to learn, whether the artillery of those countries is actually cast in 

 this way. 



Mr. Cochran, of the United States, has a patent for the water-core system, 

 but we have been unable to ascertain to what extent it has been successfully 

 put in practice. Casting in chill is another process also beset with difficulties ; 

 some experimental trials made at St. Helens during the last six months show 

 that great uncertainty exists as to the result. Further experiments, however, 

 and a more extended practice may eventually remove the difficulties. 



Extracts from a letter addressed to the Committee by Mr. J. Beaumont 

 Neilson, dated Glasgow, Sept. 20th, 1855. 

 Mr. J. B. Neilson, the inventor of the hot blast, who has had great ex- 

 perience in casting metals, recommends that guns, if made of Avrought iron, 



