from the spindle top to the "nip" of
the rollers, thus imparting the requisite strength to the roving as it
issues from the rollers. The mechanism for revolving the spindles is by
no means difficult to understand, simply consisting of a number of
shafts and wheels revolved at a constant, definite and regulated speed
per minute.

Not only is it necessary to provide special apparatus for twisting the
cotton at the bobbin and fly frames, but also very complicated and
highly ingenious mechanism for winding the attenuated cotton in suitable
form upon the bobbins. Indeed it is with this very mechanism that some
of the most difficult problems of cotton spinning machinery are
associated.

Although the cotton at this stage is strengthened by twist, yet it is
extremely inadvisable and practically inadmissible to insert more than
from 1 to about 4 twists per inch at any of these machines, so that at
the best the rovings are still very weak.

If too much twist were inserted at any stage, the drawing rollers of the
immediately succeeding machine could not carry on the attenuating
process satisfactorily.

This winding problem was so difficult that it absolutely baffled the
ingenuity of Arkwright and his contemporaries and immediate successors,
and it was not until about 1825 that the difficulties were solved by the
invention of the differential winding motion by Mr. Holdsworth, a
well-known Manchester spinner, whose successors are still eminent master
cotton spinners.

This winding motion is still more extensively used than any other,
although it may be said that quite recently several new motions have
been more or less adopted, whose design is to displace Holdsworth's
motion by performing the same work in a rather more satisfactory manner.

In these pages no attempt whatever will be made to give a technical
explanation of the mechanism of the winding motion. It may be said that
it was a special application of the Sun and Planet motion originally
utilised by Watt in his Steam Engine, for obtaining a rotary motion of
his fly-wheel.

Sufficient be it to say that this "Differential Motion," acting in
conjunction with what are termed "Cone drums," imparts a varying motion
to the bobbins upon which the cotton is wound, in such a manner that the
rate of winding is kept practically constant throughout the formation of
the bobbins of roving, although the diameters of the latter are
constantly increasing.

The spindles and bobbins