Introduced by the American Watch Tool Co. in 1909 and subsequently developed under the direction of Frederick W. Derbyshire (and named by him) this was a larger-capacity, more heavily built watchmakers' lathe that, whilst retaining the 50 mm centre height of the ordinary models, had its maximum capacity increased to 80 metric (5/16")
The Magnus was available in three bed lengths:
12" with one supporting pedestal foot and admitting 4" between centres,
15" with one pedestal and admitting 7" between centres and 18" with two pedestals and admitting 10" between centres.
The lathe was eventually made available with a choice of either plain, hardened cone bearings with a top speed of 4,500 rpm - and a guaranteed to run to within 0.000025" concentricity - or with a ball-bearing headstock when the maximum speed rose to (a then) amazing 18,000 rpm - and the spindle ran true to within two tenths of one-thousandths of an inch. A compact polishing and de-burring unit - using a ball-bearing 18,000 rpm headstock driven by a 1/12 hp electric motor - was also marketed using the 'Magnus' name..

A Magnus with 12" bed, ball-bearing headstock, spring-bind collet closer attachment and a "Combination" tailstock - this latter unit accepted the same size of collet as the headstock.

An entirely different version of the Magnus based on the Model A and rigged as a Micro-drilling Lathe with a Hand-lever Collet Closer (#12550-2) and the special Drilling Attachment

Shown as a Magnus in the catalogue - but the same picture was often used to illustrate the WW lathe - this version is fitted not only with the triple compound slide but also the rare and sought-after screwcutting attachment which, with its full set of 14 changewheels, would cut both English and metric threads.

A beautiful, cone-bearing spindle, black crackle-finish Magnus lathe of the early 1950s fitted with the maker's Spring-bind Collet Closer Attachment. This device consisted of a round spring which could be closed over the headstock pulley to stop it rotating - combined with a lever-action collet opener.
The brake could be removed, and the lathe operated normally.

Another Magnus lathe with Spring-bind Collet Closer Attachment but fitted with a screw-feed cross slide carrying a pair of high-speed grinding heads on swivelling bases. Lever feeds were optional on all the screw-feed movements.