Made in Bristol, England, by the firm of Humpage, Thompson & Hardy, who described themselves as "High-class machine-tool makers, the H.T.H. lathe was a small backgeared and screwcutting 2.75" x 12" machine of unusually high quality that incorporated several unusual and interesting features. The lathe, priced at £8 : 10s 0d on its introduction, was protected by "Patent No. 4392 of 1922", and  have been introduced just post the Great War. It appears to have been a combination of ingenious deign and attempts to keep construction costs to a minimum - two ideals which have always been difficult, if not impossible, to reconcile. The patent may have concerned (at least as fitted on some models) the unusual arrangement of the backgear mechanism, a full-length type mounted inside the lower part of the headstock casting with the engagement lever - a thin strip of steel - set between the end face of the headstock and the changewheel bracket. At the left-hand end of the headstock the casting was swollen to accommodate the larger of the backgears with the smaller positioned directly under the (unguarded) spindle bull wheel. The headstock bearings, instead of being the simple, split-type frequently found on less expensive lathes, were (judging by the photographic evidence) obviously of superior construction, but details of their design are not known.
Of very unusual cross section - sketched below - the bed had a shape mirrored in the construction of the compound-slide ways. This design is also seen in the slide-rest of a beautifully constructed triangular-bed lathe, circa 1810-1815, preserved in the Bridwell Museum, Norwich. Attributed to Johnson Jex, a Norfolk blacksmith (though in reality he must have been a highly-skilled engineer) this lathe was used to turn clock parts. The Jex is mentioned (p.28) in Steeds' 'A History of Machine Tools 1700-1910',  where, because the unusual ways were carried on a sub-bed, Steeds suggests they may be a later addition. How H.T.H. came to use the same design is, of course, a mystery.
Cast as one piece, the saddle and apron of the H.T.H. were off-set to the left of the cross-slide centre line, with the carriage traverse driving by a gear that engaged directly against the leadscrew, exactly in the manner as employed decades later on the Myford ML10. For a small lathe the leadscrew was of unusually large diameter, with the clasp nut a double-split type engaged by lever on the apron incorporating a positive, snap-in-and-out action using a spring-and-ball indent.
Both top and cross-slide feed screws lacked micrometer dials and were threaded "right-handed" - an arrangement that caused the slides to move in a "cack-handed" wrong where turning the handwheel to the right caused the slide to retract rather than advance. The screws were fitted into "open" retainers, with the thrust taken from each end of the screw by the inside faces of the casting. The top-slide was cast with a large boss on top machined to accept what must have been a standard-fitment round tool post, not unlike that used on the modern Hobbymat MD65 lathe.
Another example of simple but effective engineering, the tailstock had its No. 1 Morse-taper barrel slotted on its underside to engage with a handwheel that ran up and down a screwed bar threaded into the casting beneath it. The barrel had a small hole drilled through it so that the centre could be knocked out.
Available for either bench mounting - with a simper, round-base countershaft that had the drive and driven pulleys arranged to overhang on opposite sides -  or fitted to a steel-framed stand with one drawer and treadle drive, the HTH was supplied complete with a compound slide rest (with its circular toolpost) and a set of changewheels included in the basic price of £16 (during the 1920s). For an extra £4 : 15s : 0d it could be supplied on a rather wonderful oak stand of the type illustrated below - complete with a most unusual rigid 'dust cover'.
H.T.H. also offered a 2.5-inch centre height lathe that could be had either as a plain-turning machine or fitted with backgear and screwcutting. Both models were of simpler construction than the larger HTH and  incorporated several cost-saving features.
If you have an H.T.H. lathe (several were known to have survived into the early 2000s) or any literature about them, please do contact the writer..