During the first half of the eighteenth-century, cornices were simply extensions of the bookcase or cabinet carcase.
From around 1760, the cornice became a separate structure sitting atop the carcase. The giveaway is often a barely visible gap beneath an astragal, or other small moulding (the first element of the cornice), that was intended to disguise the break between carcase and cornice.
The purpose of the loose cornice was two-fold: firstly, savings could be made in expensive mahogany (or other show wood) and secondly, the whole was much less prone to damage during transportation if the main elements were demountable. Breakfront bookcases are usually comprised of eight or more separate components and could not exist if not demountable.
Loose cornices consist of dovetailed (some were merely nailed together), box-like pine frames around which were applied the various moulded elements. The tops of the frames were either left open, or enclosed – which made it easier to dust the top of the piece and also provided a suitable platform on which to fashionably display an oriental vase or ginger jar.
I knocked together a pine cornice frame and began working and attaching the composite mahogany mouldings.