30 ANNUAL OF SCIENTIFIC DISCOVERY. 



pocked backwards and forwards by the gang, so that every part 

 may be well hammered. So soon as the redness goes off they 

 are finished, so far as this part of the operation goes. So far 

 they have received some of the glance, or necessary polish ; they 

 are again heated, and treated differently in this respect, that in- 

 stead of having powdered charcoal strewed between them, each 

 two red-hot sheets have a cold finished sheet put between them ; 

 they are again hammered, and, after this process, are finished as 

 far as thickness and glance go. 



"Thrown down .separately to cool, they are taken to the 

 shears, placed on a frame of the regulation size, and trimmed. 

 Each sheet is then weighed, and, after being thus assorted in 

 weights, they are finally sorted into first, second, and thirds, ac- 

 cording to their glance and freedom from flaws and spots. A 

 first-class sheet must be like a mirror, without a spot in it. 



"100 poods of balvanky make 70 pounds of finished sheets; 

 but this allowance for waste is far too large, and might easily be 

 reduced. 4 heats are required to finish. 



" The general weight per sheet is from 6 to 12 pounds, the 

 larger demand being from 10 to 11 pounds, but they are made 

 weighing as much as 30 pounds, and may then almost be called 

 thin boiler plates, being used for stoves, etc. Besides the fin- 

 ished sheets, a quantity of what are called red sheets are 

 made, which are not polished, and do not undergo the last 

 operation. 



" Taking the Michsslofskoi Works, which are the largest sheet- 

 iron ones in the empire, I found that the power running the sheet 

 rolls was equivalent to 40 horses, the rolls making 70 to 80 revo- 

 lutions a minute. The hammers used are powerful, 'having the 

 surface of the stroke very large, just the contrary shape ^here 

 to the ordinary tilt-hammer. A gang turns out in a shift from 

 450 to 500 sheets. 



"In the Central Works, where they make sheet iron from pud- 

 dled iron, they roll it into the necessary size, and then roll this 

 balvanlty into half-ready sheets with the same sort of rolls as are 

 used in the North, but which, however, run much slower; the 

 finish being given also by hammers in the same manner, but 

 leaving out the final part of the operation of placing cold fin- 

 ished sheets between the hot unfinished ones. The hammers are 

 not so heavy, and the heating furnaces are not so well constructed 

 and do not regulate the flame as well. The trimming, sorting, 

 etc., are carried out in just the same way. 



"The waste is really greater in the Central Works than it 

 should be in the North, as the hammered iron does not leave such 

 a raw edge as the puddled. 



"A fact that proves the superior manufacture of the North 

 over the north parts of the empire is, that whereas in the former 

 sheet iron is the best paying, in the latter it is the worst busi- 

 ness. . . . 



" For the uses to which sheet iron is put ductibility is of the 

 first consequence, and no sheet iron is of passable quality that 

 that will not bend 4 times without breaking ; some made in the 



