In most circumstances, ensuring hinged elements are level and secure is essential: A table with misaligned drop leaves is certain to topple a glass at some point, and baize or leather writing surfaces that bridge uneven hinge lines will inevitably tear or split (figs. 1 and 2).
The minimum number of hinges required for a table leaf or bureau fall to function is two and while adding a third hinge to a long table leaf (fig. 3) might be an obvious remedy to address misalignment; adding a third hinge to a bureau fall would be a hindrance as the hinge knuckle would be somewhat obtrusive.
In these days of abundant and affordable hardware, installing one or two additional hinges on a table leaf would certainly be an option, though in the seventeenth- and eighteenth-centuries, blacksmith- or whitesmith-made iron hinges would have been costly and not so readily available.
The square adjoining edges of early gate-leg table tops and drop-leaves are often an unhappy coincidence (figs. 3 and 4).
Alignment, at least, was improved with the introduction of mating reed-and-flute-moulded edges (fig. 5).
The greatest development in table-to-leaf interfacing – and the one most readers will be familiar with – came in the form of cavetto (female) and modified ovolo (male) moulded edges; correctly termed a table-leaf joint (fig. 6) – and not the more common ‘rule joint’ (the folding wooden ruler with its similar looking joint wasn’t invented until the mid-nineteenth-century).
There is another means of locating adjacent hinged edges that was employed – albeit infrequently on tables – which was both simple to implicate and efficient in use.
Sounding peculiarly like a good English ale house, the ‘lug and mortise’ comprises two short (an inch or less) narrow mortises chiselled into the mating edges, into one of which is glued a short piece of wood – the lug. The protruding end of the lug is lightly bevelled, rounded, or even tapered to allow ease of entry into the opposing mortise (fig. 7).
Lugs and mortises found favour with cabinetmakers; bureau falls being one such instance (figs. 8 and 9).
Lugs were capable of keeping the wide expanse of otherwise unsupported falls aligned with the carcase side of the writing surface. In such an intimate environment, this was essential and allowed baize and leather linings a reasonable lifespan.
Lugs were also employed on card tables and bachelor- and dressing chests with fold-over tops; the lugs affording much needed support during the pressing of clothes with the tops folded out (fig. 10).
While projecting lugs are not particularly attractive, they are effective at keeping hinged elements aligned as long as detritus isn’t allowed to build up around the lug or in the open mortise.
Lugs are not a cure for falls already bowed or warped: A distorted fall – if not manually assisted at the appropriate point as it travels through its arc – can foul the lug, which, acting as a fulcrum, can easily break soft brass hinges or tear them from their settings.