In the automatic reeling machine this is the method employed for
regulating the supply of cocoons. The counterweight being suitably
adjusted, the lever falls when the thread has become fine enough to
need another cocoon. The stop, T, and the lever serve as two parts of
an electric contact, so that when they touch each other a circuit is
completed, which trips a trigger and sets in motion the feed apparatus
by which a new cocoon is added. In practice the two drums or pulleys
are mounted on the same shaft, D (Fig. 1), difference of winding speed
being obtained by making them of slightly different diameters.

The lever is mounted as a horizontal pendulum, and the less or greater
stress required according to the size to be reeled is obtained by
inclining its axis to a less or greater degree from the vertical. An
arrangement is also adopted by which the strains existing in the
thread when it arrives at the first drum are neutralized, so far as
their effect upon the lever is concerned. This is accomplished by
simply placing upon the lever an extra guide pulley, L¹, upon the side
opposite to that which corresponds to the guide shown in the diagram,
Fig. 2.

An electric contact is closed by a slight movement of the lever
whenever the thread requires a new filament of cocoon, and broken
again when the thread has been properly strengthened. It is evident
that a delicate faller movement might be employed to set the feed
mechanism in motion instead of the electric circuit, but, under the
circumstances, as the motion is very slight and without force, being,
in fact, comparable to the swinging of the beam of a balance through
the space of about the sixteenth of an inch, it is simpler to use a
contact.