periphery. The beak is intended to enter and detain the loops of upper
thread, and lead them so that they ultimately envelop the shuttle, a motion
of the thread which is chiefly due to the oscillation of the shuttle in a
vertical plane. The oscillating movement is to the extent of 180 degs. of
the circle, which suffices to cast the loops freely over the shuttle. The
center of oscillation is not coincident with the center of the shuttle; but
it is nearly so with the periphery of the thread reel, and exactly
coincides with the point where the under thread is drawn from the shuttle,
_g_. The shuttle thread is thus entirely freed from any tendency to twist,
an objection frequently urged against circular or revolving shuttles. It
will be observed, also, that the body of the shuttle is extremely narrow.
Bulging of the thread loops to one side or the other is thus obviated.

But the long beak in this description of shuttle serves an important
purpose other than that of seizing the upper thread loops, otherwise a very
short beak would be preferable. It adds so much to the efficiency of the
machine that a little further explanation of it appears essential. In the
old fashioned machines the thread required to envelop the shuttle was
dragged downward through the cloth, while the needle still remained in the
fabric. This necessitated the use of large needles with deep side channels,
to enable the thread to run freely, and as a consequence the punctures that
had to be made in the fabric were unnecessarily large, and could not in any
case be entirely filled by the thread, a condition which is now recognized
as essential in linen stitching and for waterproof boots.

The long beak in both shuttles and hooks offers an immediate solution of
the old difficulty experienced with long shuttles. When the needle begins
to rise, the shuttle commences to oscillate, through the loop, the motions
so coinciding that the long beak, c, merely detains the loop until the eye
of the needle has ascended above the cloth; then, and then only, does the