EEPORT OF THE AECHITECTS. 173 



returning the water of condensation in the coils to the boilers, at a tem- 

 .perabure of about 175 degrees, instead of heating new supplies of water 

 from an average winter temperature of 56° to the boiling point, special 

 efforts were made in this direction. In order to prevent clattering and 

 noise the steam-pipes have a fall from the boilers, so that any condensed 

 water flows in the same direction with the steam and not against it, until 

 points are reached where the steam-pipes are tapped and discharge the 

 condensed water into the return pipes, which are started at the extreme 

 end or lowest point of the flow-pipes with an adequate fall toivards the 

 boilers. 



The extreme length of each of two lines of steam-conducting and re- 

 turn water-pipes is about an eighth of a mile. 



To promote the usefulness of the building, these whole systems of 

 pipes were buried in large-sized underground ducts. The grade of the 

 public sewers does not allow the boilers to be set deep enough for re- 

 turning the condensed water to them exclusively by gravitation, as is 

 most desirable, hence it is conducted into a receiver located on the floor 

 of the boiler-room, from which it is raised by automatic steam-traps lo- 

 cated above the boilers. These traps are, firstly, supplied with steam 

 from the boilers. They are so constructed that by the movement of a 

 lever connected with a float the steam is shut off, when it condenses 

 in the traps, causes a partial vacuum, and lifts the water from the re- 

 ceiver into the traps by suction. As the ascending water fills the traps 

 it lifts the float, the lever of which gradually opens the steam- valve, 

 permits the steam to enter the traps, and at the same time causes an 

 equalization of pressure in the boilers and traps whereby the water, by 

 gravitation, flows back into the boilers. To operate these traps no more 

 pressure is required than sufficient to raise the water from the receiver 

 to the trap. 



Since immediately after starting the fires the pressure in the boilers 

 may be too small, a steam-pump is at hand by which the water is forced 

 direct from the receiver into the boilers. This pump works with less than 

 two i)ounds pressure per square inch, and forces either hot or cold water. 

 When a fresh supply of water should be desired and the steam-pressure 

 is greater than that in the main water-pipes, the pump is connected with 

 these mains and the boilers supplied therefrom. Ordinarily the boilers 

 are fed direct from the water mains. 



The steam for warming the building is generated in four tubular boil- 

 ers of 56 inches diameter and 15 feet length, containing each 72 tubes of 

 3 inches diameter. The heat of the fire passes first under the whole 

 length of the boilers, then back through the tubes and finally over the 

 top of the boiler, giving the greatest possible exposure of surface and 

 resulting in the greatest attainable economj^ of fuel. 



The boilers are connected overhead by steam-pipes of 5 inches diame- 

 ter from each, with stop-valves ; these lead into a drum of 12 inches di- 

 ameter to which two 8-inch main steam-pipes are attached, each of which 



