by the Bower-Barff process for prevention of rust. The shelves are 38 inches in length and 12 inches deep. They are not solid, but are formed of parallel bars of steel, fixed in a framework about a quarter of an inch apart, the top surface of each bar being slightly rounded. The shelf framework at either end hooks into the vertical supports, and by slightly tilting can be removed or raised. They can be adjusted at intervals of an inch. A book support has been designed for these special shelves, which is useful, and easily applied. It is a thin plate of steel about 8 inches by 6, with a short piece of wire projecting from the centre of its shortest side. This goes through the shelf between any two of the bars, and is kept in position by a thumbscrew on the other side. If required for tall folios a second support can be screwed on to the shelf above and hang downwards to support the top of the book.
Each stack-room will shelve 800,000 volumes. The shelving already fixed in the whole building is estimated to be sufficient for about two million volumes, and the ultimate capacity of the library, when shelved to its full extent, will be upwards of four and a half million volumes.
The remaining floor space of the first storey is used for various administrative purposes, including the copyright records and the housing of the scientific library belonging to the Smithsonian Institution. The second floor contains an art gallery, 217 feet by 35 feet, and a similar sized room for the great map collection of the library.
