Defective Windows. In other stacks, you will find windows too short (even if there is a cross band, it should not be more at the most than eighteen inches in height, leaving a window on each deck, six feet full down from the deck above), but oftener windows narrower than the aisle, giving too little light to reach the inner ends of the cases. There is no excuse for these. As has been said above, there is no structural need to build the piers between windows wider than the book cases inside, and just so much as they encroach upon the windows they commit the unpardonable sin of darkening the stack.
Many modern plans show this defect.
False Windows. By these I mean windows which outside take the gridiron stack form, but do not come truly and fully opposite every aisle inside.
“The rear elevation of the New York Public Library plainly shows that the architects wilfully omitted to place a window at the end of each aisle. All the beauty of the elevation will not make good the want of light in the lower floors of the stack.”—Oscar Bluemner.[299]
The falsity of this arrangement, which is found in many modern libraries, lies in using an exterior scheme which does not meet inside conditions. The excuse is that sufficient diffused light is provided for the whole stack. But if this is true (which I cannot concede), any other equal window area could be used in any other form, which would not give outer promise of inward excellence. They are only a sham, and can therefore be called false stack windows.
Heating. The best form developed for stacks is by hot water or steam pipes along the walls just above the floor of each story clear of the books, with coils in the windows. Overhead pipes are very bad, as they concentrate heat at the top of each story, where it is most oppressive to those walking or working below.
Ventilation. There should be an air space above the top shelves in a stack. Good ventilation can be provided there by end windows and through the side windows. Some writers have advised sealed windows so as to be dust proof. In that case some system of forced draft would have to be installed.
The ventilation of a stack, where use by staff and public is only intermittent, is perhaps not so important as that of reading rooms constantly crowded, but the open construction and height of the stack differentiate the problem rather than avoid it.
Underground. In England, Burgoyne says[300] four stories is the rule. But in America, every library builds its stack, in all dimensions, according to its wants and space. Four-story stacks are common, but by no means the limit.
The impending exigencies of storage have not only brought suggestions of dark stacks in the interior of a building, but they have already carried stacks under ground. Even the Bodleian Library in England has installed a two-story subterranean stack, mechanically lighted and ventilated, under its front lawn. Plans are on foot for stacks many floors below ground-level, to be lighted and aired by electricity. See [p. 222].