constructed to be driven by belt, friction, or direct engine, as may be
desired. The important requisite in this class of mills is such design
and proportion of parts as will insure durability and continued movement
at the highest speed, safely increasing the quantity and improving the
quality of work done at a lesser feed, and admitting the use of thinner
saws than is practical in the slower moving sash. These are among the
advantages gained in the iron frame machine, overcoming the necessity
of an expensive mill frame, saving time and expense in setting up, and
avoiding the liability of decay or change of position.

[Illustration: IMPROVED IRON FRAME GANG SAW MILL.]

Many improvements have been made in the mechanism of oscillation, and
from these the builders of this mill have adopted what is known as the
Wilkin movement, which oscillates the top and bottom slides. The top
slides are pivoted at the top end, and the bottom ones from the bottom
end, both being operated by one rock shaft from the center. This
movement when properly adjusted gives an easy clearance and the easiest
cut yet obtained. It adds no extra weight to the sash, and avoids the
cumbrous rock shaft and its attendant joints, usually weighing from
three hundred to five hundred pounds, which have been found so
objectionable in many other movements. The feed is continuous, and is
made variable from 1/4 to 11/4 inch to each stroke, controllable by the
sawyer. Power is applied to the press rolls in the double screw form
with pivot point, also operated by the same hand. A special feature of
this machine is the spreading of the lower frame so that its base rests
upon an independent portion of the foundation from the main pillow block
or crank shaft. The solidity of the whole structure is thus increased,
both by the increased width at the base and the prevention of connecting
vibrations, which necessarily communicate when resting upon the same