Birch "front-way" backgeared and screwcutting lathe
Constructed to the same design as the original Rivett 8-inch Precision, the Birch front-way" lathe is obviously from the late 1800s - the use of simple crank handles and the exposed gearing on the front of the apron confirm its era. However, for its time, the ideas incorporated were advanced, especially for a small machine, and all is not as it would at first seem. Incorporating some ideas from the Birch range of ornamental turning lathes, the spindle was hardened and the headstock incorporated a special arrangement to absorb end thrust, the makers claiming that, as the spindle warmed, the adjustment was not affected - the bearing for this running in an oil bath. As an optional extra, the cross slide could be fitted with micrometer dial of an unusually large diameter that read to 0.001" - a useful fitting that was also equipped with what appears to have been a properly engineered 'face lock' that did not disturb the setting when operated. Inboard of the cross-feed handwheel was a lever, possibly used for the rapid advance and retraction of the cross slide when screwcutting. Power cross feed was fitted, driven by a universally-jointed, telescopic shaft from a gear above that on the end of the carriage rack-pinion gear (and possibly incorporating worm-and-wheel gearing to get the feed rate down). Engagement of the feed was by a cone clutch formed on the inside of one of the two exposed gears on the face of the apron, a simple two-handle capstan wheel being provided to push it into engagement on the driven shaft. The cross and top slide could be elevated vertically - as on the Spencer - by a screw controlled by a handwheel positioned below the carriage. The height adjustment provided a quick means of setting the tool height and also allowed some versatility when milling with a cutter held on an arbor between centres. Ingeniously, to provide a fine carriage feed by hand, a worm engaging with a wheel on the end of the leadscrew was fitted at the tailstock end of the bed; the carriage feed handle from the apron almost certainly able to be transferred to fir on the worm's square-ended shaft.
Even the backgeared headstock was far from standard and fitted with what appears to have been no fewer than six rings of indexing holes. Might there have been a method of locking the spindle? An operating crank handle can be seen protruding forwards below the pulleys. The makers described the mechanism thus: . ...the cone pulley can be locked to the spindle by a concentric friction arrangement, keeping the spindle in balance whether the backgear is in or out ...

A less complex Birch front-way lathe with a double saddle arrangement. The saddles are connect together and move as one, that on the left with the hand T-rest able to pass in front of the headstock and so bring into position that carrying the compound slide-rest assembly

Build with centre heights of 3.5", 4.5" and 6" the Birch backgeared and screwcutting centre lathe was a typical product of the late 1800s. Driven from a treadle flywheel assembly by a round rope "gut" leather band the 4-speed headstock was reported to run in parallel bearings - though the illustration appears to a show a draw-in type. The single flywheel (some models would have had another, at the tailstock end to store additional energy) was fitted with a high-speed pulley close to the centre and cranked by a full-length hardwood treadle board. Instead of the expected, simple slide-into-engagement backgear, this was carried on a proper eccentric. Screwcutting changewheels drove a very large diameter, coarse-pitch leadscrew through a tumble-reverse mechanism. Instead of a rack-pinion gear (and rack on the bed) the carriage was moved by hand using a rather cheaper method - a gear engaging with the top of the leadscrew. Although not shown, the lathe would have been supplied with a wooden "backboard" (sitting behind the bed and spanning the legs) for the storage of tools. Birch "commercial" lathes always had 'square' ways, generally a centre height of 6 inches, flat-belt drive and a screwed spindle nose 13/8" in diameter. The company's ornamental turning lathes - an example is shown below - were based on identical major castings but with dovetail ways, a 5.5" centre height, round leather 'gut'rope drive and a smaller headstock spindle nose 11/5" in diameter.

W ell-specified Birch of Manchester ornamental turning lathe complete with a complex "overhead" drive system for powering toolpost-mounted drilling and grinding attachments, backgear, screwcutting,  a dog clutch on the leadscrew and possibly tumble-reverse on the changewheel drive.
Pictures of Birch ornamental turning lathes are very welcome 

A less-expensive incarnation of the Birch, a plain lathe without backgear and screwcutting but complete with a range of what would have been pricey accessories.