MEMOIR OF DANIEL TREADWELL. 



449 



tliick, and 15 inches lonsj (or broad), I take a flat bar, nay 14 iiiclios wide, from half an incli to 

 an inch thick, and of such length that, when wound into a coil, it shall form the thickness 

 required for the hoop, after allowing for the waste in welding, forging, and finishing. After its 

 ends have been scarfed to a long wedge form, it is to be heated to a low red heat, and then 

 wound upon a cylinder of say 25 or 26 inches' diameter, as a ribbon is wound upon a block. 

 Next, it is to be heated in a proper furnace to a good welding heat, and then, being placed upon 

 an arbor, or mandrel, of about 25 or 26 inches' diameter, and between proper dies, sets, or 

 swages, it is to be completely welded, or the several layers or coils arc to be made to form one 

 piece. This may be done by compressing it with the swages, by a hydrostatic press, or by a 

 steam hammer. After it is properly welded and condensed in this way, and has cooled as low as 

 600°, it is to be placed ujiou a cold arljor, or mandrel (shown, in section, at A, A, Figures 1 and 2), 

 which is supported at both its ends liy the upright studs of the heavy iron fi-ame B, B. It is 



Fig. 1. 



Fio. 2. 



then to be hammered by the steam hammer C, until its internal diameter is enlarged to about 27 

 inches. The last part of the hammering is to be performed after the hoop has become cold. 

 Instead of operating in this way with the steam hammer, we may produce the same effect upon 

 the hoop by a rolling-mill, in which the operating part of the rollers is made to project beyond 

 the housings, or frame. 



" After the hooj) has been condensed ahd enlarged in this way, it is next to be placed upon an 

 annular anvil, D, D (Figures 3 and 4), and the segmental swages or blocks, E, E, are to be 

 adjusted within it. These segments form a cylinder u)ion tlieir outer surface, but inside they 

 form a hollow cone. A solid conical plug, F, is fitted to bo di'ivcn into this hollow cone within 

 the swages. With this arrangement, the whole being under the drop or steam hammer C, the 

 plug is driven by repeated blows into the hollow cone, by which operation the hoop is stretched 

 sufficiently to destroy all conflicting strains or tensions that might have been produced in it by 

 the hammering. The strain is thus reduced to a circuml'ercntial direction, and the hoop put as 

 near as possible into the condition of the hard wire, after it had been subjected to the first 

 series of strains. 



