306 
[Assembly 
was obtained except a greater facility in producing it. A few slight 
surface cracks were seen near the close of the operation. 
A third trial of a similar kind on a bar annealed and cooled in dry- 
ashes resulted like the preceding, but exhibited rather more cracks on 
the exterior surface of the bend than either of the foregoing. 
Another trial of the toughness of this iron when cold, was made by 
drawing out a bar .7 of an inch wide, .18 inch thick, and 5.4 inch long, 
and twisting it cold in the manner of a common twisted auger, twice 
round in the length just specified. The edges of the spiral were now 
exactly 7 inches long. Hence, the elongation of the exterior fibres on 
.7—5.4 
the edges was — 29.6 per cent. It is proper to state that this 
5.4 
experiment was made after annealing the bar, and cooling it off in dry 
ashes. In attempting to carry the torsion beyond this extent, the bar 
was twisted off at the jaws of the vice, in which the operation was per- 
formed. 
Having thus proved that this iron is not under any circumstances 
cold-short, I caused the bar l|- inches wide, and .6 inch thick, to be 
heated to a fair working red heat, and in that state bent flatwise over 
the corner of an anvil, and a right angle exterior and interior to be 
formed f of an inch from the end. The exterior angle remained per- 
fectly sound. On the interior, a thin scale only of metal appeared to 
be corrugated and partly detached from the rest of the mass, owing, 
probably, to a defect in welding — but not the least sign of a tendency 
to fracture was discovered. Another portion of the same bar was heat- 
ed as before and 3 inches of it bent over and hammered flat upon the 
face of the adjacent part. 
Complaints are made by workmen that much of the iron which they 
employ will not sustain either of the two preceding operations. They 
were, however, borne by the iron under trial, without evincing any 
weakness or undue distortion of parts. 
A third test of the quality of this iron, when hot, was afl'orded by 
heating about 3 inches near the end of the bar and driving a steel ^ j 
punch .8 of an inch in diameter, quite through it. This was done 
without sphtting or cracking at the edges, as is too often the case in 
making screw nuts. Machinists are well aware of the importance of a \ 
good material for the formation of screws and nuts. 
