70 UNITED STATES NATIONAL MUSEUM 



Exceptions to the style of window above described, varying in 

 size, mostly narrow and all of iron construction, occur in the south 

 and north pavilions, and in the court walls of the stair towers and 

 service stair wells. 



First and second story windows. — In order to adequately light the 

 wide exhibition halls, the extent of window surface as compared with 

 wall surface in the first and second stories has been made propor- 

 tionately very great. The window openings, as elsewhere explained, 

 are continuous through both stories, measuring 31 feet 10 inches high 

 in the outer walls of the east and west wings, and 31 feet 6 inches 

 high in the range and court walls, from the top of the masonry sill 

 which is 3 feet 11 inches above the first floor level. In the outer 

 walls of the east and west wings they reach to within 5 feet 2 inches 

 of the ceiling of the second story, and in the range and court walls 

 to within 5 feet 6 inches of the ceiling. The width of the openings is 

 11 feet 6 inches in the outer walls and typically 11 feet in the court 

 walls, making the intervening piers 1 feet wide in the former and 

 7 feet 6 inches wide in the latter. 



The window construction, which carries the effect of a single 

 window throughout the entire height of each opening, is almost en- 

 tirely of molded steel, rigidly fastened to the masonry of the open- 

 ing. Though substantially put together, it presents an appearance 

 of great lightness and permits the use of an exceptional amount of 

 glass for the area covered by the frame. The windows are deeply 

 recessed from the outside, but are nearly flush with the interior sur- 

 face of the walls. The panels which separate the upper from the 

 lower windows and cover the steel construction of the second floor 

 where it crosses the openings are 2 feet 11 inches wide and built of 

 No. 20 steel, decorated on the outer surface with rosettes of stamped 

 zinc inserted in molded panels. 



With respect to their framework, the windows are divided by 

 4^-inch mullions into three principal sections, and the middle and 

 larger section again by 1^-inch vertical muntins into three parts. 

 These vertical lines carry through both stories. In the first story the 

 two side divisions are divided by horizontal muntins into five equal 

 lights. The lowest muntin, however, also extends entirely across 

 the window, and the two outer subdivisions thus formed in the 

 central section of the window have lights with angle iron frames, 

 hinged at the top to open out. In the second story the side divi- 

 sions are also divided by muntins into five parts, the upper division 

 being smaller than the others, and the line carrying entirely across 

 the top of the window as a transom bar. As in the first story, the 

 lower muntins also extend across the middle division and there 

 are two movable sashes in each window, being the second light from 

 the bottom in each side or jamb division. 



