the hand-driving gang, also by the gang at the steam-riveting machine
for a long period of time, in both cases making no allowances of any
kind of delays, the rivets driven per month by each was--for the hand
driven rivets at the rate of twelve rivets per hour, and for the
machine driven rivets, 120 per hour. In the case of the hand driven
rivets the boiler remains stationary and the men move about it, while
the machine driven rivets require the whole boiler to be hoisted and
moved about at the riveting machine to bring each hole to the position
required for the dies. Notwithstanding the trouble involved in
handling and moving the boiler, it shows that it is possible to do ten
times as much work, and with less skilled labor, by the employment of
the riveting machine.

_Calking._--One great source of danger in boiler making is excessive
joint calking--both inside and out--where a sharp nosed tool is
employed, and for the reason that it must be used so close to the
inner edge of plate as to indent, and in many cases actually cut
through the skin of the lower plate. This style of calking puts a
positive strain upon the rivets, commencing distortion and putting
excessive stress upon rivets--already in high tension before the
boiler is put in actual use. It is, I hope, rapidly becoming a thing
of the past.

With a proper proportion of diameter and pitch of rivet, all that is
required is the use of a light "fuller tool" or the round-nosed tool
used in what is known to the trade as the "Connery system."

There is but little need of calking if means are taken to secure a
clean metal-to-metal face at the joint surfaces. When the plates are
put together in ordinary course of manufacture, a portion of the mill