These notches, _b b'_, similarly serve as guides
to insure uniformity of spacing in the subsequent operations of
punching out the links.
The second operation (illustrated in Fig. 2) is to punch out of the
pair of opposite webs, _a a_, pairs of oblong mortises--two pairs, _c
c_, and one pair, _d d_. These three pairs of mortises (which might be
punched at separate operations, but are preferably punched at one
stroke of the press) are situated as close as possible up to the faces
of the other pairs of webs, _a' a'_, the pairs of mortises, _c c_,
being so spaced as to correspond in position to the eyes of the links
to be formed, to which they correspond approximately in form, while
the pair, _d_, correspond in position to the notches, _b_, and
therefore to the intervals by which the links formed out of the same
pair of webs, _a a_, will be separated when completed. This operation
is continued along the whole length of the pair of webs, _a_. It will
be observed that a considerable thickness of metal is left at _a*_
between the notches, _b_, and the mortises, _d_. This is of primary
importance and is one of the essential features of my method of
manufacture, inasmuch as by first punching out the mortises, _d_, the
subsequent removal of the metal from between the outer ends of the
links is greatly facilitated, while by leaving the solid metal, _a*_,
the transverse strength of the webs, _a a_, is not materially
diminished, so that when the operation of punching the mortises, _c_
and _d_, in the other pair of webs, _a'_, is performed the bar will
not be bent and crippled, as would inevitably be the case were the
whole of the metal opposite the notches, _b_, which is ultimately to
be removed, to be punched out at so early a stage of the manufacture.
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