Mr. Sweet, which represented three forms of lathe and planer
construction. The box form, c, proved to be fifty per cent. stronger
in its vertical direction than either a or b, fifty times stronger
sideways than a and twenty times stronger than b, and more than
thirteen times stronger than either when subject to torsional strain.

a, Fig. 2, represents an ordinary pinion tooth, and b shows one of
the same size strengthened by cutting put metal at the root; c and
d were models showing the same width of teeth extended to six times
the length, showing what would be their character if considered as
springs. ]

A similar arrangement applies to the lathe and machine tools of that
character--that is, machines of considerable length in proportion to
their width, and with beds made sufficiently strong within themselves
to resist all bending and torsional strains, fill the requirements so
far as all except wear is concerned. That is, if the frames are once
made true, they will remain so, regardless of all external influences
that can be reasonably anticipated.

Among wood-working machines there are many that cannot be built on the
single rectangular box plan--rested on three points of support.
Fortunately, the requirements are not such as demand absolute straight
and flat work, because in part from the fact that the material dealt
with will not remain straight and flat even if once made so, and in
the design of wood-working machinery it is of more importance to so
design that one section or element shall remain true within itself,
than that the various elements should remain true with one another.

The lathe, the planing machine, the drilling machine, and many others