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 forms, long used in
mechanism--the _cone_ and the _screw_. In screw cones we possess a perfect
compensator, and it is surprising that parts of mechanism so hung appear
subject to very little wear. Another advantage, too, is gained by the
introduction of screw cone bearings; the friction is always greatly reduced
by their use. In every case the fine adjustment of the cones is securely