62 UNITED STATES NATIONAL MUSEUM 



and built in accordance with the typical plan, which are used as 

 machine shops, etc. A large compartment at the northeast corner of 

 the wing serves as a coal bunker, and another large room has been 

 formed by walling off about two-thirds of the width of the space 

 originally included in the inner driveway. 



In order to light the corridors their walls are mostly provided 

 with transoms, which also occur in certain other long walls opposite 

 windows. Typically, each 18^-foot unit or bay of these walls con- 

 tains a rectangular opening, 13 feet 9 inches long, which begins 11 

 feet above the floor and has a height of 4 feet 8 inches. These light 

 units are divided hj steel muUions into five equal windows with 

 double sash, the lower stationary, the upper hung on chains and 

 weights so that it can be entirely lowered. The frames, which are 

 set in the middle of the 9-inch walls, the sash, trims, etc., are of 

 molded pressed steel; the glass, of which there is an area of 36f 

 square feet in each unit, is clear plate, wired, and I inch thick. 

 This arrangement has been followed in the two ranges, in the north 

 wing, and in the north and south walls of the lengthwise corridors 

 of the west wing. In the north wing the openings have plaster 

 molded sills, but elsewhere they are flush all around. The transom 

 lights in the east wing and in a few other isolated positions are of 

 simpler construction. 



First and second stones. — In the east and west wings of the first 

 story the central skylighted parts of the great halls have been screened 

 from the aisles at the sides by plain plastered walls of the entire 

 height of the story, which are built between the piers of the lateral 

 rows except in the outer interspace at both ends of each of these 

 rows. In the east hall these walls are of brick and 10 inches thick, 

 but in the west hall they are of macite reenforced with steel rods and 

 4^ inches thick. 



In the central hall of the north wing, where the walls were built 

 for hanging pictures, the construction is quite different, consisting 

 of a reenforced macite core covered on both sides with wood, which 

 in turn is covered with burlap. The area comprised within the 

 screening extends to the crossrow of piers at the north, and the walls 

 return at both ends so as wholly to enclose the space except for the 

 entrances, of which there is one at each end. The walls are only 

 13 feet 11 inches high, leaving an opening of 3 feet between their 

 top and the under surface of the ceiling girders which span the piers. 

 The enclosure is subdivided by partitions of the same height and 

 character as the outer walls into eight rooms with three short 

 corridors. 



The space between the stairs and elevator shaft at the extreme 

 northern end of the north wing is enclosed in front by a hollow wall 

 of terra cotta. 23 inches thick, which encloses foujr structural columns 



