merely
anticipated by a few years the mechanical progress of his time. His
large removable bar-lathe was a highly important tool of the same kind.
It was used to turn surfaces many feet in diameter. While it could be
used for boring wheels, or the side-rods of marine engines, it could
turn a roller or cylinder twice or three times the diameter of its own
centres from the ground-level, and indeed could drive round work of any
diameter that would clear the roof of the shop. This was therefore an
almost universal tool, capable of very extensive uses. Indeed much of
the work now executed by means of special tools, such as the planing or
slotting machine, was then done in the lathe, which was used as a
cutter-shaping machine, fitted with various appliances according to the
work.

Maudslay's love of accuracy also led him from an early period to study
the subject of improved screw-cutting. The importance of this
department of mechanism can scarcely be overrated, the solidity and
permanency of most mechanical structures mainly depending on the
employment of the screw, at the same time that the parts can be readily
separated for renewal or repair. Any one can form an idea of the
importance of the screw as an element in mechanical construction by
examining say a steam-engine, and counting the number of screws
employed in holding it together. Previous to the time at which the
subject occupied the attention of our mechanic, the tools used for
making screws were of the most rude and inexact kind. The screws were
for the most part cut by hand: the small by filing, the larger by
chipping and filing. In consequence of the great difficulty of making
them, as few were used as possible; and cotters, cotterils, or
forelocks, were employed instead. Screws, however, were to a certain
extent indispensable; and each manufacturing establishment made them
after their own fashion. There was an utter want of uniformity. No
system was observed as to "pitch," i.e. the number of threads to the
inch, nor was any rule followed as to the form of those threads. Every
bolt and nut was sort of specialty in itself, and neither owed nor
admitted of any community with its neighbours. To such an extent was
this irregularity carried, that all bolts and their corresponding nuts
had to be marked as belonging to each other; and any mixing of them
together led to endless trouble, hopeless confusion, and enormous
expense. Indeed none but those who