d down for
that purpose, my own experience leads me to speak in favor of the admirably
governed "Otto" gas engines made by Crossley Bros. These are especially
steady, a feature of no small moment in moving stitching machinery of
various kinds.

Much attention has been devoted to the invention of controllers of the
motive power supplied to sewing machines. The principle of the friction
disk has found most favor. In many cases two of these plates, fast and
loose, are placed upon the main shaft, and their separation and contact
controlled by the treadle. The great sensitiveness of the friction
attachment employed by the Singer company is due chiefly to the
transference of the friction plates to the axis of the machine itself (Fig.
13). Their contact and separation are controlled by a lever worked by a
very slight movement of the treadle. But the chief point of interest in
this device lies in the combination with the lever of a brake, enabling the
operator, by a simple reversal of the treadle's motion, to instantly
suspend the rotation of the machine. The forked lever, in fact, acts
simultaneously in throwing off the motion and applying the brake. The speed
is always in direct proportion to the pressure exerted upon the treadle,
and a single stitch can be made at will. Fig. 14 shows the friction wheel
separated, the portion a being fast, and e loose.

[Illustration: FIG. 13.]

[Illustration: FIG. 14.]

The Wheeler & Wilson company do not confine themselves to any particular
controller, but prefer the form shown here this evening (Fig. 15), in which
two bands and an intermediate pulley are employed. The first band is left
rather loose, and the machine is set in motion by the tightening of this
band through the depression of the treadle. The speed varies in proportion
to the pressure applied, and the sensitiveness of the arrangement is
increased by a brake device coming into play by the reversal of the treadle
as before.

[Illustration: FIG. 15.]

Messrs. Willcox & Gibbs depend upon a similar device shown in three
varieties to-night.

_Speed of Power Sewing Machines_.--The fastest practicable speed of a
machine worked by the foot appears to be 1,000 stitches per minute. Most
operators can guide the work at a much higher rate, especially in tailoring
or on long seams. The average speed upon such work is 1,200 stitches per
minute; but many lock-stitch machines are run at 1,500 and 1,800 per
minute, and even at much hig