628 THE BUILDING FOR THE LIBRAKY OF CONGRESS. 



are so disposed as to admit of any desirable subdivision of a more or 

 less permanent character that experience may indicate. At the same 

 time, the arrangements of windows, ventilation, and communication, 

 and the strength of floors are such that any part or the whole of any 

 of the long halls may be conveniently occupied by shelved books, while 

 the corner pavilion rooms are favorable for staif work, reading, etc., 

 and contain also lavatories and stairways. 



The building is less exposed and better guarded by having but two 

 entrances, a double or two-story one in front, and a single one in 

 rear. The first is for the general use of the jjublic and the other espe- 

 cially for the delivery and dispatch of freight. The front or main 

 entrance opens into a great staircase hall, 132 feet wide by 122 feet 

 deep, extending the full height of the pavilion through the first and 

 second stories, constructed of veined white Italian marble in richly 

 ornamented design, the vaulting of the lower story in marble mosaic, 

 and that of the upper story in painted decoration. This hall has a full 

 basement on the ground floor which serves as the entrance hall from 

 the porte cochere. 



The great reading room or main rotunda opens directly from the 

 stair hall. It is surrounded by two tiers of alcoves shelved for books, 

 and surmounted by a gallery 35 feet above the floor, wherefrom visitors, 

 not desiring to read, may view the rotunda. Special students will find 

 quiet spaces iu the alcoves. The reading room has a clear diameter of 

 100 feet, with hemispherical dome whose crown is 125 feet above the 

 floor. The dome lantern and semicircular clearstory windows of 32 

 feet diameter above the gallery furnish the light. A few small 

 windows open into some of the alcoves from the courts. By means of 

 translucent glass tlie direct rays of the sun are sufficiently softened in 

 the southerly windows. The catalogue and attendants' counter and 

 desk of circular form are placed in the middle of the floor, and the 

 readers' tables are arranged around this in three concentric circles. 

 The central desk is in communication with the several stories of the 

 book stacks at all times by means of pneumatic tubes for written mes- 

 sages and speaking, electrical annunciators, and endless-chain book 

 carriers operated by electric motors. The side walls are composed of 

 an alternation of narrow brick piers and plate glass openings extend- 

 ing the full height of the building, admitting ample light from the courts 

 throughout the stack. 



An elevator, stairway, and the endless-chain book-carrier are located 

 in the middle of the stack. The windows are fixed and air-tight, all 

 air for warming and ventilation being passed up through the stack 

 from the subbasement by natural draft or fans, and discharged at the 

 roof. Each of the larger stacks will hold 800,000 volumes, and the 

 smaller one about 175,000. This shelving and that of the reading room 

 alcoves will together accommodate about 2,000,000 volumes, which is the 

 present capacity of the shelved portion of the building. The capacity 

 of the large halls above noted as available for extensions of the shelv- 



