while the hand rivet is very imperfect. This experiment was tried
several times, with similar results each time.

The hand rivet, it will be observed, filled up the hole very well
immediately under the head formed by the hammer; but sufficient
pressure could not be given to the metal--or at least it could not be
transferred far enough--to affect the metal at some distance from the
driven head. So great is this difficulty that in hand riveting much
shorter rivets must be used, because it is impossible to work
effectively so large a mass of metal with hammers as with a machine.
The heads of the machine rivets are, therefore, larger and stronger,
and will hold the plates together more firmly than the smaller
hammered heads.

To drive rivets by hand, two strikers and one helper are needed in the
gang, besides the boy who heats and passes the rivets; to drive each
five-eighths inch rivet, an average of 250 blows of the hammer is
needed, and the work is but imperfectly done. With a machine, two men
handle the boiler, and one man works the machine; thus, with the same
number of men as is required in riveting by hand, five rivets are
driven each minute.

The superior quality of the work done by the machine would alone make
its use advantageous; but to this is added greatly increased amount of
work done.

The difference in favor of the riveting machine over hand riveting is
at least _ten_ to _one_.

In a large establishment a record of the number of rivets driven by