Note 42 — Bookcases.

Tonks' fittings are specially adapted for the shelves of book-cases or other shelves, the adjustment of which has, from time to time, to be varied to suit the varying requirements of a library, &c. The method hitherto generally adopted for such shelves is to support them at each end by two studs, the heads of which are mortised into the shelf, and the pins driven or otherwise fitted into holes two or more inches apart, bored in two rows into the upright frames; these holes are very seldom accurately fitted to the pins, and even where so done in the first instance, from the shrinking or expansion of the wood, they soon become too large or too small for the pins, and the alteration of the adjustment of a shelf is thereby rendered an extremely troublesome operation. The patent fittings remedy this, and save both time and trouble; in place of the rows of holes so far apart, metal strips perforated at intervals of three-quarters of an inch for the reception of the very simple but strong metal plates, which take the place of the old studs, are mortised in and screwed to the frames. The insertion, at the required intervals, of the plates into the perforations in these strips is made instantaneously, consequently the position of a shelf can be easily altered without an irritating expense of trouble, and waste of time. The thinness of the plates renders any mortising in the shelf unnecessary, and the small intervals between the perforations in the strips enables the whole space occupied by the shelves to be used most economically. These fittings, when used with a shelf sufficiently strong itself to bear the weight, will support without strain more than half a ton.