involved in the Construction of Artillery. 373 



Mr. James C. Maxwell, in a very able paper, in " Trans. Roy. Soc, Edinb.," vol. xx., 

 pt. I., p. 87, &c., " On the Equilibrium of Elastic Solids," has investigated, in his third and 

 ninth cases, problems which are closely related to those here in question in the text. Unfor- 

 tunately, his calculations all assume the elasticity of the body perfect — a condition which the 

 researches of Professor Hodgkinson have shown to be far from practically applicable to any 

 of our known materials of construction. Soc also E. Clarke's "Brit. Bridge," vol. i., p. 451, 

 as to the effects of previous strains beyond the elastic limit, on subsequent ones within 

 the same, and transversely applied. 



As respects the distribution of heat in the mass of solids, in relation to its unequal dif- 

 fusion in heated guns, see Duhamel, " Sur les Equations generales de la Propagation de 

 la Chaleur dans lea Corps" (Jour, de I'Ecole Politech., t. xiii., p. 357) ; and Poisson, " Memoire 

 sur la Distribution de la Chaleur dans les Corps Solides," Idem, t. xii., p. 144, and second 

 Mem., p. 249. 



Note L.— (Sect. 133.) See Note C. 



Note M. — (Sect. 141.) 



See Note O. 'I'he Reports of M. F. le Plaj', Eng. des Mines (in "Ann. des Mines," 

 4me ser., t. iii. p. 503, and t. ix. p. 113) comprise one of the most complete accounts of 

 the steel manufacture in England, and abroad, that has been produced. See also list of 

 German authors at conclusion. 



Steel made by the direct or puddling process, has long been a branch of industry in 

 many parts of Germany, where it is applied with great economy, to a number of objects, for 

 which we content ourselves with cast-iron or other material. It is afforded at prices from 

 one-half to one-third that of our English cast-steel. 



At the Exhibition of 1851, amongst the products of the ZoUverein, was puddled steel 

 from the works of Messrs. Lehrkind and Co., of Haspe, near Hagen, of very good quality, 

 at £22 per ton, at the Works. For fine-cutting tools, or other purposes demanding a keen 

 and persistent edge, however, it is immeasurably inferior to English cast-steel, produced by 

 cementation. 



Note N (Sect. 149.) See Note S. 



VOL. XXIII. 3 c 



