100 UNITED STATES NATIONAL MUSEUM 



suspended from the ceiling of the engine room, and thence distributed 

 through a system of piping in the tunnels and chases. The tempera- 

 ture of the water is maintained constant by means of a thermostat in 

 the tank, which regulates the opening and closing of an automatic 

 diaphragm valve in the pipe supplying steam to the heater. 



For the disposal of sewage there is a 12-inch cast-iron pipe extend- 

 ing north and south through each court and under the northern 

 ranges, and separate pipes of glazed terra cotta, 5 to 15 inches in 

 size, around the outside of the building, all of which combine and 

 discharge into a city sewer directly north of the north entrance. 

 These sewers receive the soil pipes from the various plumbing in- 

 stallations, the downspouts from the roofs, the area drainage and the 

 drainage from the tunnels under the ground floor. The pipes are 

 mainly of cast iron, and vary in size from 4 to 6 inches. 



INTERIOR OP THE FINISHED BUILDING, ITS ARRANGEMENT, DIMEN- 

 SIONS, EQUIPMENT AND USES 



GENERAL ACCOUNT 



In its adaptation to the requirements of natural history collections 

 this new structure must be accorded the foremost position among the 

 museum buildings of the world ; and despite its large size it is notable 

 for the compactness and convenience of its arrangement. The sub- 

 jects represented are wholly cared for under the same roof, and the 

 exhibition collections, the reserve collections and the laboratories re- 

 lating to each are, therefore, closely associated. 



As described in the foregoing pages, the building comprises four 

 stories which are indicated on all of the facades by as many tiers of 

 windows, besides a certain amount of space in each wing immediately 

 under the roofs which is also available for museum purposes. There 

 are two public entrances, one at the middle of the north front, facing 

 B Street, the other at the middle of the south front, facing the park 

 or Mall. The former opens on the ground floor, the latter, which on 

 account of its architectural position is the main entrance, on the first 

 floor. The principal stairs and the passenger elevators are located 

 near them, and while both are large and either would be ample for 

 the admission of any number of persons who might be expected to 

 visit the Museum at one time, in view of the size and arrangement of 

 the building, there seemed to be no way of avoiding this duplication, 

 which is mainly objectionable in that visitors depositing their um- 

 brellas, canes and other objects at one entrance must find their way 

 back to the same entrance on leaving. The other entrances, three in 

 nimiber, are all in the ground story. One under the south portico and 

 opening into the driveway connecting the basement areas in front of 

 the east and west wings furnishes the most direct communication with 



