84 UNITED STATES NATIONAL MUSEUM 



following method has been adopted in place of the general system: 

 On a platform suspended from the ceiling between the boilers is 

 placed a 4-foot Sturtevant steel plate, full-housed fan, having its 

 discharge connected to a series of galvanized iron ducts carried along 

 the ceiling, with openings opposite each window. Dampers in the 

 branches from these distributing ducts permit the amount of air 

 delivered to be regulated. The principle involved is the removal of 

 the hot air which collects above the boilers and its discharge in the 

 several rooms at the points mentioned, the rooms being thus warmed 

 without the expenditure of energy other than that represented by 

 the motor operating the fan. This scheme is quite a departure from 

 the ordinary, and it has worked satisfactorily. 



Steam connections with other huil'dings. — The steam for heating 

 the several buildings occupied by the Museum on the southern side 

 of the Mall is now supplied from the new plant through the medium 

 of an underground tunnel which extends from the east wing of the 

 new building to the Smithsonian building a short distance east of 

 the main entrance. The tunnel is 730 feet long, 4 feet wide and 5-J 

 feet high, and has a flat roof. It is built of concrete reenforced with 

 steel rods, and is 6 inches thick on all sides. The top is sloped and 

 troweled to a smooth surface, and covered with a coat of tar paper 

 followed by 3 inches of sand to prevent seepage. It has also been 

 constructed with reference to its drainage to a given point, so that 

 any water that may enter can be removed by means of a steam 

 siphon. 



The steam pipe running through the tunnel is 4 inches in diameter. 

 Starting from the 9-inch main near the boilers, it enters the old 

 5-inch main in the Smithsonian building under the east door. The 

 steam pressure at this point, namely, 80 pounds, a loss of 20 pounds 

 in the passage from the boilers, is continued to the boiler room in the 

 older Museum building where the pumps are located. Three reducing 

 valves belonging in the original system are used to further diminish 

 the pressure from 80 pounds to approximately 15 pounds. The pumps 

 return the water of condensation to the new plant through a 2-inch 

 pipe. There has been no material change in the heating system of 

 the older buildings which is by means of steam, the original pipes 

 and radiators remaining in use. The heating surface in these build- 

 ings is practically all of the direct radiation type and amounts to 

 about 20,000 square feet. 



ELECTRICAL EQUIPMENT 



Use of electricity. — Electricity is generated for both lighting and 

 power. With the exception of the generator engines, the two stoker 

 engines and the six pumps in the engine room, which are operated 

 by steam, all motive power is supplied by electricity, including the 



