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.

But the specific improvements in plain sewing machines, to which I have had the honor of drawing your attention, do not exhaust the list, and, time permitting, it might be considerably augmented.  Nor must it be inferred that advancement has taken place exclusively in those systems of sewing machinery now before us.

Accessories to Sewing Machines.—­The number of special attachments that have been successfully adapted to plain sewing machines has multiplied so rapidly of late, that only one or two of the more notable can be spoken of on this occasion.  Perhaps the most generally useful of these is the trimmer, an arrangement consisting of a vibrating knife, which trims off the superfluous edge of a seam as the machine stitches it.  These are in extensive use in the factories at Leicester, Nottingham, and elsewhere, while Northampton and Norwich use the same device for paring the seams in boot upper manufacture.  The chisel-like knife is usually actuated by a cam rotating with the main shaft, and one or two of the usual forms of this attachment are to be seen here this evening on both lock and loop stitch machines.