le fifteen feet into hard ground
at the rate of 65 blows a minute. The driver was first used in forming
the great steam dock at Devonport, where the results were very
striking; and it was shortly after employed by Robert Stephenson in
piling the foundations of the great High Level Bridge at Newcastle, and
the Border Bridge at Berwick, as well as in several other of his great
works. The saving of time effected by this machine was very
remarkable, the ratio being as 1 to 1800; that is, a pile could be
driven in four minutes that before required twelve hours. One of the
peculiar features of the invention was that of employing the pile
itself as the support of the steam-hammer part of the apparatus while
it was being driven, so that the pile had the percussive action of the
dead weight of the hammer as well as its lively blows to induce it to
sink into the ground. The steam-hammer sat as it were on the shoulders
of the pile, while it dealt forth its ponderous blows on the pile-head
at the rate of 80 a minute, and as the pile sank, the hammer followed
it down with never relaxing activity until it was driven home to the
required depth. One of the most ingenious contrivances employed in the
driver, which was also adopted in the hammer, was the use of steam as a
buffer in the upper part of the cylinder, which had the effect of a
recoil spring, and greatly enhanced the force of the downward blow.

In 1846, Mr. Nasmyth designed a form of steam-engine after that of his
steam-hammer, which has been extensively adopted all over the world for
screw-ships of all sizes. The pyramidal form of this engine, its great
simplicity and GET-AT-ABILITY of parts, together with the circumstance
that all the weighty parts of the engine are kept low, have rendered it
a universal favourite. Among the other labour-saving tools invented by
Mr. Nasmyth, may be mentioned the well-known planing machine for small
work, called "Nasmyth's Steam Arm," now used in every large workshop.
It was contrived for the purpose of executing a large order for
locomotives received from the Great Western Railway, and was found of
great use in accelerating the work, especially in planing the links,
levers, connecting rods, and smaller kinds of wrought-iron work in
those engines. His circular cutter for toothed wheels was another of
his handy inventions, which shortly came into general use. In
iron-founding also he introduced a valuable practical improvement. The