3 i6 THE POPULAR SCIENCE MONTHLY. 



and in its passage it was " sheared " or " slit " (hence the name 

 " slitting-mill ") into a number of bars or rods of the same width 

 as the thickness of the cutters in use at the time. The shafts 

 carrying the cutters could be taken from the frames or " hous- 

 ings " in which they revolved, and the cutters could be removed 

 and replaced by others thicker or thinner as desired. The slit- 

 ting-mill in Fig. 17 gets its motion from the same water-wheel 

 shafts, E O, that drive the rolls C D. 



John Houghton, in his Husbandry and Trade Improved, 

 printed in 1697, speaks of rolling and slitting mills as " late im- 

 provements " ; * speaking of the operation of " slitting " iron bars 

 that have been hammered out in a " blomary," he says : " They 

 are put into a furnace to be heated red-hot to a good height, and 

 then brought singly to the rollers, by which they are drawn even, 

 and to a greater length ; after this another workman takes them 

 while hot, and puts them through the cutters, which are of divers 

 sizes, and may be put on or off according to pleasure. Then 

 another lays them straight, also while hot, and when cold binds 

 them also into fagots, and then they are fit for sale." 



By comparing this description of John Houghton's with Fig. 

 17, the original of which was published sixty-eight years later, it 

 will be evident that very little change had taken place in the con- 

 struction of slitting-mills in that period. 



The furnace (whose door is seen at Y, in Fig. 17), in which 

 the rough-hammered bars from the " blomary ' : were heated 

 preparatory to rolling, was peculiarly constructed, and had fire- 

 boxes, P R, on each end. Sections of this furnace are shown in 

 Fig. 18 ; No. 1 being a longitudinal vertical section through the 

 fire-boxes, P R, and the reverberatory heating-chamber Q ; No. 2 

 a vertical transverse section of the heating-chamber Q, the chim- 

 ney q q, and its hood q. It will be observed that the chimney 

 of this furnace is not placed, as in a modern iron heating-fur- 

 nace, at one end of the heating-chamber, while the fire-box is 

 at the other ; but that it is located outside and in a measure de- 

 tached from the body of the furnace, and that the products of the 

 combustion of the wood (which was the only fuel used) burned 



* The earliest publication known to me, in which the use of " rolls " for drawing and 

 shaping metals is described, was written by Giovanni Branca. In his work, Le Machine 

 (published at Rome in 1629), he gives a very curious illustration of a rolling-mill, which, 

 notwithstanding its manifest absurdity, suffices to show that he understood the action of 

 the " rolls " and their advantages. The next mention of the use of rolls for giving shape 

 to metals pnssed between them is contained in a work by Vittorio Zonca, published at 

 Padua in 1656. In this work Zonca gives an engraving and description of a mill for roll- 

 ing the double grooved fillets of lead which were used for securing the glass in stained 

 windows. We regret that our limited space prevents us from reproducing these illustra- 

 tions, neither of which has ever been referred to in any history of the manufacture of 

 metals. 



