94 UNITED STATES NATIONAL MUSEUM 



a second heater of the same type as the first, the heaters being de- 

 signed for winter use only. It is discharged from the fan into 

 galvanized iron ducts located in the furred ceiling of the corridor 

 surrounding the auditorium. 



For ventilating the auditorium the greater part of this air is led 

 into vertical ducts built in the walls at the northeast and northwest 

 sides of the auditorium, which lead downward and open into the 

 chamber under the raised floor. The distribution throughout the 

 room is mainly by means of several hundred small elongate openings 

 in the successive surfaces of the step-like arrangement on which the 

 chairs are fastened. These openings, in fact, lead into metal registers 

 incorporated in the side standards of the chairs, so that the air be- 

 comes diffused instead of rising in a mass from each opening. There 

 is also a chamber under the speakers' platform, from which the air 

 escapes through large registers in the front of the platform. The 

 air is withdrawn from the auditorium through four large register 

 openings in the ceiling connected with a flue on the west side, which 

 extends to the attic space of the west wing and has a Blackman fan 

 at the outlet. 



In the rotunda, two branches from the main duct direct the air into 

 flues at the southeast and southwest corners, in which are located 

 heaters of the same type as those in the fan room, the discharge being 

 near the ceiling of the first story through large rectangular registers. 

 This circulation serves the double purpose of ventilation and heating. 

 The rotunda is further heated by means of radiators similar to the 

 above placed in flues on the north side of the rotunda near the stairs. 

 The air enters the flues through register openings in the first story, 

 is raised in temperature and passes out at the third story. 



Alcoholic sjyecimen roonb. — This room, which occupies the entire 

 middle part of the ground story in the west wing, and measures about 

 130 feet long by 52 feet 11 inches wide and 18 feet 8 inches high, is 

 furnished to nearly its full height with stacks of shelves for the stor- 

 age of specimens preserved in alcohol. Being as completely isolated 

 within the building as the auditorium, it is equally dependent on 

 artificial agencies for its ventilation, which are required to be effectual 

 in order to dispose of the noxious and inflammable fumes resulting 

 from the evaporation of this preserving fluid. 



Air is admitted to the room close to the floor through gratings in 

 the bottom rails of the thirteen doors. A large galvanized iron outlet 

 duct runs the entire length of the ceiling, from which it is suspended, 

 on the north side of the central row of piers. Two branches enter 

 this duct in each unit of length, one from each side, but since the 

 southern part of the room is slightly longer than the other there are, 

 in fact, thirteen branches in all. They are approximately 2 feet long 

 with conical openings protected with ^-inch wire mesh, but, while the 



