As books to be inspected are best nearly opposite the eye of a reader standing or sitting, live books would better not be stored on lower shelves in any open-access cases. These shelves nearest the floor might be used, therefore, for similar sets not often needed.
Miss Marvin[265] advises uniform height for wall-shelving all over the building.
Low bookcases, “dwarf bookcases,” both in wall-shelving or floor cases, are often used, for different reasons, especially to serve as partitions, and have not the disadvantages of cases too high. In floor-cases, the top can be used as a convenient ledge. In this form, low cases can be set anywhere on the floor without seriously obstructing light, ventilation, or supervision, and low cases can be used against the wall when high-set windows are needed to throw light further across a room.
Unusual Shapes or Sizes of Books. Minimos, (sizes under the ordinary duodecimos) are so unusual that they can be shelved at the ordinary intervals; and if a set or lot of such small books come together, movable shelves can be closed together, without much waste of depth (or by doubling back, with no waste).
Folios and quartos occur in all libraries, in the smallest as books of reference, like dictionaries and atlases; in larger libraries they may come anywhere. Formerly, the lower shelves in all cases were made wider, with a ledge above, but this made the aisles so much wider than was necessary for shoulder room above, that ledges are not now much used in floor-shelving or stacks. Instead, special shelving is provided not far off on each floor, and slips or dummies put on the shelves to indicate where the larger volumes ought to come in the regular classification, and where they can be found when wanted.
This special shelving is often put along the walls, but in late stacks I have found it convenient at both ends of each story. The necessary ledge can be widened without much sacrifice of space, into a shelf at table height, which can be put to many purposes, part of it at one end being cut into to give room for the stack stairs, which usually rob either books or users of more room elsewhere. In other rooms, with wooden shelving, there is almost always a convenient recess or end, where quarto and folio shelving can be put without crowding the other cases. Indeed, when designing a library building, one thing to watch for is, where such shelving can be stowed away near at hand, with the most economy of space. In floor-cases, wooden or metal, occasional large books can be laid across two adjoining shelves.
As to dimensions, Mr. Poole’s recommendations in 1876[266] still hold good: a ledge about 34 inches high, with two shelves below, 18 and 16 inches high for folios, 16 inches deep, and as many shelves as the case will allow above, 12 inches high and 10½ inches deep. Burgoyne says,[267] 21 inches high for folios, 13 high for quartos. These are extreme. Dewey recommends 12 × 10 inches for quartos; for folios just double octavo measurement; large folios to be laid on their sides.[268]
If movable shelving is installed, it will be possible to shelve the exceptional books upright or flat, as their size and character requires.
Burgoyne[269] advises padding flat folio shelves. The British Museum uses cowhide; other libraries, canton flannel (bad) with falls.