L. MECHANICS AND ENGINEERING. 477 



be, such packing seems to be unaffected. 15 A, December 

 30,1871,890. 



ANTIQUITY OF THE MANUFACTURE OF IRON. 



The antiquity of the manufacture of iron on a large scale 

 is shown in an article, by Mr. Richard Mallet, upon the work- 

 ing of iron in India, where, according to this author, it had 

 been carried on upon a scale so stupendous as to rival the 

 production of the largest steam-hammer forges in Europe at 

 the present day. Among other illustrations mentioned is that 

 of a wrought-iron pillar at the principal gate of the ancient 

 mosque of the Kutub, near Delhi, which is as large as the 

 screw shaft of a first-class steamer. This is slightly spindle- 

 shaped, and is surmounted by a capital of elaborate Indian 

 design, carved by the chisel in the solid iron. The entire 

 length is about sixty feet. Its diameter near the surface is 

 sixteen inches; it contains about eighty cubic feet of metal, 

 and weighs upward of seventeen tons. Near its middle is an 

 inscription of six lines in Sanscrit, from which its age has been 

 assigned to the third or fourth century of the Christian era. 

 13 A, February 1, 1872, 55. 



PREPARATION OF RUSSIA SHEET IRON. 



An eminent London metallurgist has published a pamphlet 

 upon the method of manufacturing Russia sheet iron, which, 

 as is well known, differs from common sheet iron in having a 

 smooth, glossy surface, of a dark metallic gray, and not a blu- 

 ish-gray. When bent backwards and forwards by the hand 

 no scale is separated, as happens with sheet iron manufac- 

 tured by rolling in the usual manner ; but in folding it over 

 and unfolding, it simply scales from the line of folding. The 

 method of preparing this sheet iron has been kept a profound 

 secret by the Russian manufacturers for a long period of 

 time; but, by a careful collation of information given by va- 

 rious correspondents, the general theory of the manufacture 

 has been ascertained, and placed in such form as to be capa- 

 ble of practical application. One point in the preparation of 

 the iron is said to be that, after the completion of the roll- 

 ing, the sheets are made up into packages with charcoal dust 

 interposed, and then well hammered, the outer sheets being 

 afterwards thrown away as waste. 8 A, Sept. 1, 1871, 159. 



