Cylindrical needle bars, when combined with an effective system of
brushing, have proved themselves superior to every other form of slide for
lock stitch machines. But their introduction is by no means a thing of
yesterday. They were used freely in sewing machines as far back as 1860,
but were never very successful until united with the lubricating brush.
Some makers go a step further, and elaborate the system by the introduction
of steel brushes, easily renewable.

Every effort is now made to reduce, as much as possible, not only the
extent of movement of the parts in high speed machines, but the weight of
the parts themselves. Indeed, so far has this been carried that, in some of
the Wheeler & Wilson machines now shown, the needle bars consist really of
steel tubes. Small moving parts are made as light as possible, but rigidity
is secured by the free use of strengthening ribs. Many of the parts are of
cast iron, rendered malleable by annealing, and finally casehardened. Such
parts are found to be quite as durable as if made of forged steel, and are,
of course, less costly. As to the automatic tools now used in the
construction of the machines, it may be said that scarcely a file, hammer,
or chisel touches the frame or parts while they are being assembled to work
together. The interchangeable system of construction is, of course, the
only one possible for the accurate production of the millions of sewing
machines now manufactured annually.

_High Arm Construction_.--Sewing machines, as now constructed, exhibit a
rather short and very high arm, a form of framework that has been found to
contribute in no small degree to the light running capabilities of fast
speed machines. While it reduces the length of the various parts concerned
in the transference of the motive power, it adds to their rigidity and
diminishes their weight, maintaining at the same time the capacity of the
machine to accommodate the largest garments beneath the arm.