frame, in having two extra verticals, which separate it into two equal
divisions. These are necessary in order that two deals may be operated
upon simultaneously, each division being devoted to a separate deal, and
likewise to enable the connecting-rod which works the frame to pass up
the center and oscillate on a pin near the top, thereby avoiding the
deep excavations and costly foundations required where the rod is
engaged with the pin at the bottom. The rack that advances the deals to
the saws passes through a "bow" in the connecting-rod and the middle
of the frame, the deals are placed on either side of it, on rollers
purposely provided. In sawing hard deals, the saws require to be
sharpened about every tenth run or journey, and every twentieth for
soft. Fifty runs, or one hundred deals, are reckoned an average day's
work; this is inclusive of the time required for changing the saws,
returning the rack for another run, and other exigencies. For attachment
to swing-frames the saws have buckles riveted to them; these are by
various modes connected to the crossheads. Each top buckle is passed
through the crosshead and is pierced with a mortise for the reception
of a thin steel wedge or key, by whose agency the blade is strained and
tightened. The edge of the crosshead upon which the keys bed is steeled
to lessen the wear invariably ensuing from frequently driving up the
keys. The distances between the blades are adjusted by interposing
strips of wood, or packing pieces, as they are termed, of equal
thickness with the required boards or leaves; the whole is then pressed
together and held in position by packing screws. The saws themselves are
subsequently tightened by forcing home the keys until a certain amount
of tension has been attained, this is ascertained only by the peculiar
sound which emanates from the blade on being drawn considerably tight
and tense. Great experience is required to accustom the ear to the
correct intonation, as in general the tensile strain on the saws
approximates so closely to the breaking point that one or two extra taps