pable of being
bent cold in the form of a hook with parallel sides without cracks or
flaws. These requirements were thought at first to be severe, but the
makers of steel now find no practical difficulty in meeting these
specifications.

The forming of the head of rivets, whether of steel or iron, and
whether the heads are conical or semi-spherical, should not be changed
by the process of riveting. The form of the head is intended to be
permanent, and this permanent form can only be retained by the use of
a "hold fast," which conforms to the shape of the head. In the use of
the flat hold fast (in general use in a majority of boiler shops) the
form of the head is changed, and if the rivet, by inadequate heating,
requires severe hammering, there is danger that the head of the rivet
may be "punched" off. By the use of a hold fast made to the shape of
the rivet head, this danger is avoided and the original form of the
head is retained. This feature of the use of proper rivet tools in
boiler shops has not received the attention it deserves. Practical use
of the above named hold fast would soon convince the consumers of
rivets of its value and efficiency.

The practice of driving rivets into a punched rivet hole from which
the fin or cold drag, caused by the movement of the punch, has not
been removed by reaming with a countersunk reamer, or better still a
countersunk set, should be condemned, as by driving the hot rivet head
down against the fin around the hole in the cold plate caused by the
action of punching the countersunk fillet is not only destroyed, but
it is liable to be driven into the head of the rivet, partially
cutting the head from the shank. If the rivet is driven into a hole
that has been punched with a sharp punch and sharp die, the result is
that the fillet is cut off under the head, and the riveted end is also
cut, and does not give the clinch or hold desired. That is to say,
rivet holes in plates to be riveted should have the burr or sharp edge
taken off, either by countersinking, by reamer, or set.

_Heating of Rivets._--Iron rivets are generally heated in an ordinary
blacksmith's or rivet fire having a forced blast; they are inserted
with the points down into the fire, so that the heads are kept
practically cool.

Steel rivets should be heated in the hearth of a reverberatory furnace
so arranged that the flame shall play over the top of the rivets, and
should be heated uniformly throughout the entir