rture, cut partly in the
shell and partly in the face plate. The upper portion of the sleeve is
notched to receive a wrench or driver; and beneath the sleeve an armed
washer, H, is slipped over the projection. The arms of this washer
enter recesses in the face plate. It will be evident that, by turning
the sleeve, F, so that the screw works inward, the jaw and all its
appendages will be moved bodily in corresponding direction. But its
movement is limited by the arms of the washer, G, which, through the
narrowness of the recesses, are allowed only just enough play to
compensate for slight changes in the jaw. As the above device is
applied to every jaw, it follows that any one of them may be nicely
adjusted from the outside, so that all are caused to grasp the tool
accurately. The spindle, instead of being solid as represented, may be
made hollow. Patented to J.H. Vinton, August 18, 1874. For further
information, address the manufacturer, Mr. F. Armstrong, Bridgeport,
Conn.

* * * * *

SCREW-CUTTING LATHES.

[Illustration: Screw-Cutting Lathes]

An English lathe, now in use at the Rogers Locomotive Works, Paterson,
N.J., contains several novel features. The ways are flat on the faces,
instead of having raised Vs; and this is a feature of all English
lathes, and of those known in this country as the Freeland lathes. A
great deal of discussion has at various times taken place as to the
relative qualification or merits of these two forms of lathe bed. The
advocates of the flat way, with Vs at the edges of the way, claim
superiority on the score of steadiness, increased wearing surface, and
strength; while, on behalf of the raised Vs, it is urged that, the Vs
being true, the saddle is bound to travel true, because there can be
no lost motion on the slides; whereas any lost motion, from want of
adjustment of the slides in flat ways, is liable to be reproduced
twofold in the work, for the reason that 1/100 of an inch lateral
movement of the slide carriage becomes 1/50 of an inch in the diameter
of the work. Then, again, the most of the wear upon a lathe bed takes
place at the part at and near the running center of the lathe, because
the saddle is, on account of short jobs, more used in that part than
on any other. As a result, when wear has taken place, the saddle, if
adjusted to suit the worn part, becomes too tight to travel over the
unworn part of the bed; and hence, after the wear