It's a bit esoteric so I'll reveal all for you. On most lathes the accurately machined slide on the lathe bed which carry the saddle on which the cross slide and tool holder are mounted is on top of the bed. This is a copy of a lathe made by Birch of Manchester and they put the ways on the bed on the side instead of the top. More complicated and expensive to make but it meant that a rise and fall mechanism could be incorporated in the saddle. You can see the hand wheel for it at the bottom. This made it much easier and more accurate to locate the cutting point on the work-piece. Very important when doing complicated ornamental turning work.
Try this one....