REPOET OF NATIONAL MUSEUM, 1913. 13 



The skylighted section of each mng is of the nature of a great hall, 

 54 feet 8 inches high to the under side of the ceiling light, about 167 

 feet 6 inches long and 50 feet wide. Its boundaries in the first story 

 are marked by a row of large rectangular piers on each side and a 

 crossrow at the outer end, enclosing steel column supports for the 

 inner edges of the floor above and for the walls of the light well, 

 whose only piercings are certain balcony openings in the second 

 story. The interspaces between the piers in the lateral rows, except 

 the extreme one at each end, have been filled in with screen walls to 

 further mark the line of demarcation and supply additional wall 

 space for the purposes of installation. The side aisles furnish elon- 

 gate halls, about 33 feet wide, reaching to the space at the outer end 

 of the wing, which may be regarded as a fourth hall, measuring about 

 116 feet by 48 feet, except in the north wing, where its size is less 

 and where a screen wall cuts it across. Only where the screen walls 

 occur, however, is there any effect of actual division between the 

 sections of the wing, whose great dimensions of length, -w^dth and 

 height are in e^adence from practically every point of view. In the 

 second story of the wings the floor space is the equivalent of the aisles 

 and outer hall of the main story, with approximately the same 

 dimensions for each. 



From the south pavihon there are three large openings mto each 

 of the wings on the first floor, one leading to the central haU, the 

 others to the aisles. On the second floor there are only two such 

 entrances, one on each side, though an intermediate balcony opening 

 furnishes a general view overlooking the main haU. From the north 

 entrance of the building immediate access is had to only the north 

 wing, from which the others can be reached only by traversing that 

 "wdng or the ranges at the sides. 



The provisions for the lighting of the exhibition haUs are ample, as, 

 in addition to the skyUghts, the outer waUs are pierced with excep- 

 tionally large windows, whose width is 1 1 feet 6 inches as against a 

 wddth of 7 feet for the intervening piers, and whose height is only 4 

 feet to 5 feet 6 inches less than that of the stories. It is also of 

 interest to note that the length dimension of the building is based 

 on a constant unit of 18^ feet, which is the distance between the cen- 

 tei-s of successive piers, and is only disregarded in meeting architec- 

 tural requirements at the corners of the building and at the juncture 

 of walls. This arrangement lends itself to uniformity in the instal- 

 lation of exhibits, which the size of the unit adopted permits to be 

 carried out on a scale and in a manner commensurate with the large 

 size of the halls. 



The plan of three wings particularly adapts the building to the 

 three departments representing the organization of the natural his- 

 tory collections, each of which is allotted an entire wing for its exhibi- 



