=Provision for Readers.=--The reading desks are arranged in three circles, surrounding the Distributing Desk as a centre. Each row contains eight desks, leaving room between for aisles radiating from the central desk. They are constructed of dark, heavy mahogany, and are supported on iron standards with gratings admitting warm or fresh air, for heating and ventilation. The inmost row is a combination of reading-tables, settees, and standing writing-desks, with shelves for reference books,--encyclopædias, dictionaries, directories, atlases, etc.,--of which there is a very full selection. The outer rows are double-faced, and arranged exclusively for persons reading and studying. Allowing each a space of four feet, the desks are capable of seating altogether two hundred and forty-six readers. Including the alcoves, which, on account of the number of separate spaces they contain, are well adapted to the use of special students, particularly those desiring to turn over a large number of books at one time, the total number of readers that can be accommodated in the Rotunda is two hundred and eighty-nine. The Distributing Desk is surrounded by a circular counter for attendants, and for delivering and receiving books, and cases containing a card catalogue of the Library, arranged alphabetically in shallow drawers according to the subject, author, and title. It has been the policy of the Library from the beginning, moreover, to issue its catalogue in printed volumes, new editions being prepared as the old ones became obsolete on account of fresh accessions. Of late years, however, the Library has grown so enormously that the annual appropriations of Congress have not been sufficient to warrant this undertaking. The latest volumes were published in 1881, and carried the catalogue only through the letter “C.”