Office,
Record Group 241, the National Archives.)]

[Illustration: Figure 59.--1857: THE ADDITION OF METALLIC PARTS to
critical areas of wear as suggested by M.B. Tidey did not at first
radically alter the design of the bench plane. (Wash drawing from U.S.
Patent Office, March 24, 1857, Record Group 241, the National
Archives.)]

It is the plane, however, that best exemplifies the progress of tool
design. In 1876, American planemakers were enthusiastically credited
with having achieved "an important change in the structure of the
tool."[16] Although change had been suggested by American patentees as
early as the 1820's, mass production lagged until after the Civil War,
and the use of this new tool form was not widespread outside of the
United States. Hazard Knowles of Colchester, Connecticut, in 1827,
patented a plane stock of cast iron which in many respects was a
prototype of later Centennial models (fig. 58).[17] It is evident, even
in its earliest manifestation, that the quest for improvement of the
bench plane did not alter its sound design. In 1857, M.B. Tidey (fig.
59) listed several of the goals that motivated planemakers:

First to simplify the manufacturing of planes; second to render
them more durable; third to retain a uniform mouth; fourth to
obviate their clogging; and fifth the retention of the essential
part of the plane when the stock is worn out.[18]

By far the greatest number of patents was concerned with perfecting an
adjustable plane iron and methods of constructing the sole of a plane so
that it would always be "true." Obviously the use of metal rather than
the older medium, wood, was a natural step, but in the process of
changing from the wood to the iron-bodied bench plane there were many
transitional suggestions that combined both materials. Seth Howes of
South Chatham, Massachusetts, in U.S. patent 37,694, specified:

This invention relates to an improvement in that class of planes
which are commonly termed "bench-planes," comprising the foreplane,
smoothing plane, jack plane, jointer, &c.

The invention consists in a novel and improved mode of adjusting
the plane-iron to regulate the depth of the cut of the same, in
connection with an adjustable cap, all being constructed and
arranged in such a manner that the plane-iron may be "set" with the
greatest facility and firmly retained in position by the adjustment
simply of th