=The Shelving.=--The shelves themselves are open, being composed of parallel strips of steel with a narrow space between. The total number of shelves in the three stacks is sixty-nine thousand two hundred. Each is one foot wide and thirty-eight inches long, with a total length of forty and a half miles. They are capable of sustaining a weight of forty pounds a square foot--more than will ever be required of them--with practically no deflection. Nevertheless, though so much stiffer, they are as light as the ordinary board shelf of the same size. They can be easily and quickly adjusted at any height, without the need of pegs or loose screws. Once in place they cannot slip or tip, and being made in a uniform size (with some small exceptions for certain irregular spaces around stairways, etc.), every shelf is available for use anywhere. There are no rough edges or projections on which a book can wear, and the parallel strips of steel are rounded and highly polished by means of the Bower-Barff process of coating with magnetic oxide of iron, so that the surface is as smooth as glass--which not only helps to preserve the books, but can offer no lodgement for dust or insects. The open spaces, also, afford an opportunity for using a workable book-brace, specially devised by Mr. Green. Furthermore, the shelves can be removed from any compartment as desired, and space thus made for a table, a cabinet, or a desk, as needed; or an extra corridor can be at once opened for any distance. Then again, in case of the extra large books, sufficient space may be made by placing the shelves of both sides of the range on a level. [Illustration: THE ROTUNDA, LOOKING EAST.]