"Boris Beizer"

wrt meaning of "engine lathe"

An earlier definition, in my 1941 Machinists handbook and also in
the Oxford English dictionary defines it as any lathe powered by an engine
as contrasted to one powered by hand or foot. But the handbook author goes
on to admit that the "language butchers" abused the term and it then (1941)
took on the meaning of an lathe with an 8" or greater swing that has a back
gear.

Perrigo's definition by configuration, circa 1916, is fine, so far as that
goes.

But the OED is poor [how I wanted to say wrong].
In older usage, the prime mover makes no difference as to whether a lathe is an
engine lathe. It could be a treadle, or a crank, or a waterwheel, or a steam
engine, or....
In 1820's-60's usage, an engine lathe is a lathe that is self acting, that
moves the tool bit to and fro (in and out comes at the end of it) under its own
power. That's it. It has nothing to do with having a lead screw, necessarily
(feed was obtained from pulleys and rods in many such lathes), or with having
back gearing, or with having setover by means of a two-piece tailstock. It
meant only that you could engage the power, and the lathe bit would cut on its
own.
YEUMV (your engine usage may vary)
Frank Morrison