the directors of the Great Western
Steam-Ship Company sent Mr. Francis Humphries, their engineer, to
consult Mr. Nasmyth as to some engineering tools of unusual size and
power, which were required for the construction of the engines of the
"Great Britain" steamship. They had determined to construct those
engines on the vertical trunk-engine principle, in accordance with Mr.
Humphries' designs; and very complete works were erected by them at
their Bristol dockyard for the execution of the requisite machinery,
the most important of the tools being supplied by Nasmyth and Gaskell.
The engines were in hand, when a difficulty arose with respect to the
enormous paddle-shaft of the vessel, which was of such a size of
forging as had never before been executed. Mr. Humphries applied to
the largest engineering firms throughout the country for tenders of the
price at which they would execute this part of the work, but to his
surprise and dismay he found that not one of the firms he applied to
would undertake so large a forging. In this dilemma he wrote to Mr.
Nasmyth on the 24th November,1838, informing him of this unlooked-for
difficulty. "I find," said he, "there is not a forge-hammer in England
or Scotland powerful enough to forge the paddle-shaft of the engines
for the 'Great Britain!' What am I to do? Do you think I might dare to
use cast-iron?"

This letter immediately set Mr. Nasmyth a-thinking. How was it that
existing hammers were incapable of forging a wrought-iron shaft of
thirty inches diameter? Simply because of their want of compass, or
range and fall, as well as power of blow. A few moments' rapid thought
satisfied him that it was by rigidly adhering to the old traditional
form of hand-hammer--of which the tilt, though driven by steam, was but
a modification--that the difficulty had arisen. When even the largest
hammer was tilted up to its full height, its range was so small, that
when a piece of work of considerable size was placed on the anvil, the
hammer became "gagged," and, on such an occasion, where the forging
required the most powerful blow, it received next to no blow at
all,--the clear space for fall being almost entirely occupied by the
work on the anvil.

The obvious remedy was to invent some method, by which a block of iron
should be lifted to a sufficient height above the object on which it
was desired to strike a blow, and let the block fall down upon the
work,--guiding it in its descent by