implified and improved by the use
of a single angle clutch, which is found to work even when the surfaces are
freely oiled (Fig. 6).

Any motion of the free extremity of the lever upon which the biting clutch
is formed binds the latter upon the flange of the wheel, which then
advances so long as the lever continues to move in that direction. When the
stitch is completed, the clutch is allowed to recede, and is pulled back by
a reacting spring. The bite of the clutch is given by the two opposite
corners.

The feed wheel itself is free to revolve in a forward direction, but is
prevented from rocking backward in Singer's machine by an ingenious little
device, recently introduced. It consists of a small steel roller, situated
within the angle formed by an inclined plane and the flange of the wheel,
and constantly pulled into the angle by a spiral spring. Any backward
tendency of the wheel binds the roller more firmly in the angle and stops
the wheel. Former feed wheels were checked by a brake spring or block,
which retarded the motion of the whole machine when heavily adjusted.

_Feeders for Button Hole Sewing Machines_ are almost invariably of the
wheel type, but in this case the cloth is usually carried by a clamping
device, and moved in a pear-shaped path by means of a cam cut in the feed
wheel, as shown in the samples of this wonderful kind of mechanism
exhibited here to-night.

_The Compensating System of Construction_.--Compensation for wear is a part
of the mechanist's art that appears just as essential to him as
compensation for variation of temperature is to a maker of chronometers. In
the construction of sewing machines to be run in factories by power at
their utmost speed, such a system is of the greatest importance. An
effective _system_ of compensation has been eagerly sought by the best
machine makers ever since the introduction of fast speed sewing.

Compensation has been attempted here and there in the machines for many
years, but no sewing apparatus could be said to be so compensated until the
cone compensator came into use, a device which has been taken advantage of
by various makers. Save in the shuttle race itself there is not a part of
the oscillating shuttle machine subject to serious wear that cannot be
instantly adjusted to full motion by the turning of a screw, while wear in
the shuttle race can be compensated for in the usual way. This effective
system depends upon the union of two mathematical