important that these half-laps should be perfectly true and exactly
interchangeable. When one half-lap is taken off for repairs, another
half-lap must be ready to take its place on the cylinder. The original
mode in which the cylinders were made rendered it a matter of mechanical
difficulty--almost an impossibility in the machine shop--to produce them
exactly alike. To avoid this difficulty, Messrs. Dobson and Barlow have
reconstructed the combing cylinder, and the parts being fitted together by
simple turning or boring, accuracy and interchangeability can always be
depended upon. The screws which fasten the cylinder to the shaft are also
cased up with the cylinder tins, thus avoiding any accumulation of fly on
the screw heads.

The motion for working the top detaching, the leather, or the piecing
roller, as it is variously called, has also been improved. The ends of
this roller are always carried on the top of two levers that are
oscillated by a connecting rod attached to their bottom ends. In the new
motion the connecting rod is dispensed with, and one joint saved. The
joint that remains is at the foot of the levers that carry the leather
roller. This joint is constructed so that it may be easily altered, and by
its means one of the most delicate settings of the combing machine, viz.,
that of the leather roller, may be made with greater readiness than with
the old system. Further, from the mode of mounting these rollers another
advantage is gained in the facility of setting them. In setting with the
old arrangement, only one end of the roller is adjusted at a time; in the
new, the adjustment sets the ends of two rollers. With regard to the
leather roller also, it was found that as the round brass tubes in which
its ends revolved had very little wearing surface, they got worn into
flats on the outside, and thus worked inaccurately. In the machine under
notice this defect is remedied. The tubes are made square on the outside,
and having ample bearing surface they keep their adjustment perfectly.