MECHANICS AND USEFUL ARTS. 29 



scribed, we shall have a very efficient furnace and a perfect pre- 

 venter of smoke ? The 20 toothed wheels and 2 worms have 

 been reduced to 1 worm and wheel ; the 2 hoppers (one over 

 each flue) to 1 hopper in the middle of the boiler face. The 

 crushing rollers have been done away with altogether, and an 

 arrangement substituted which crushes and metres the fuel as 

 effectually but much less suddenly. Through the fuel in the 

 middle of the hopper passes a cast-iron screw, with a tapering 

 helix of small diameter at the centre, but increasing gradually up 

 to the internal diameter of its containing c} 7 linder outside the hop- 

 per. The 2 halves of this screw are right and left handed, 

 respectively. It has a slow revolving motion, and its action on 

 the coal contained in the hopper is evidently of a nibbling kind, 

 while it metes out to the fans of each flue the desired quantity of 

 fuel. There are other details which have not been overlooked, 

 such as the well-known heaping up of the coal on the dead-plate, 

 the cause of which has been entirely removed. And last, but not 

 least, the whole machine is fixed to a frame made fast to the 

 boiler, by 3 bolts through the shell, no holes whatever being 

 cut in the boiler face. The fires made by this apparatus are per- 

 fectly level, and are absolutely free from even light smoke. 



I hold in my hand a report prepared about 4 months ago, on 

 the efficiency of the apparatus in question. It is founded on very 

 carefully made evaporative experiments, the conclusion being 

 that the feeder, when used for the first time in competition with 

 the best hand-firing that could be obtained, gave an increased 

 efficiency of 9.696 per cent, over and above the efficiency already 

 attained with the argand furnace alone. The cost of the com- 

 bined apparatus is, of course, much lower than that of any of the 

 more elaborate mechanical stokers, little more than one-half; 

 but I believe the efficiency is higher. 0. E. Deacon, British As- 

 sociation. 



MANUFACTURE OF RUSSIA SHEET IRON. 



Herbert Barry, Esq., late director of estates and iron works 

 of Vuicksa, thus describes the manufacture of sheet iron in 

 Russia : 



" The refined iron is hammered under the tilt-hammer into 

 narrow slabs, calculated to produce a sheet of finished iron 2 

 archimes by 1 (56 inches by 28 inches), weighing when fin- 

 ished from 6 to 12 pounds. These slabs are called balvanky. 

 They are put in the reheating furnace, heated to a red heat, 

 and rolled down in 3 operations to something like a sheet, 

 the rolls being screwed tighter as the surface gets thinner. 

 This must be subsequently hammered to reduce its thickness and 

 to receive the glance. A number of these sheets having been 

 again heated to a red heat, have charcoal, pounded to as impal- 

 pable a powder as possible, shaken between them through the 

 bottom of a linen bag. The pile then receiving covering and a 

 bottom in shape of a sheet of thicker iron, is placed under a 

 heavy hammer ; the bundle, grasped with tongs by two men, is 



