APPLYING CARRIER TELEPHONE SYSTEMS 567 



sions, is used on routes where an ultimate of 100 systems is expected, 

 while the smaller one, 21 ft. X 24 ft., is used on a route to be developed 

 for a maximum of 60 systems. The ceiling height in these buildings is 

 sufficient to care for 11 '-6" relay racks. Eleven of the small buildings 

 and 22 of the larger ones have been built on the carrier projects so far 

 completed. 



The architectural treatment of the exterior of these buildings varies 

 somewhat, depending upon the location of the site selected and the 

 character of the buildings in the immediate neighborhood. The pres- 

 ent designs may be classified as three types; i.e., plain brick with no 

 trim, plain brick with limestone trim, and plain brick with limestone 

 trim and artificial windows. In the latter type the window arrange- 

 ments are obtained by the use of a wooden frame and sash with rough 

 wire glass, backed by the interior brick wall. The brick portion behind 

 the window is painted buff on the upper half facing the window, and 

 black on the lower half, to simulate a true window with the shade half 

 drawn. Typical examples of these types may be seen in Fig. 8. The 

 type of building selected for each station depended upon the locality. 



Arrangements have been provided in these buildings for auto- 

 matically controlling the heating and ventilation by the use of thermo- 

 statically controlled electric heater and fan units. Although experience 

 was generally lacking on the heating and ventilating problem for these 

 stations, tentative requirements were set up. A minimum tempera- 

 ture of 40° F. has been considered satisfactory for the operation of the 

 equipment in these stations and the thermostat has been set to turn 

 on the heater unit if the inside temperature drops below that point. 



Ventilating equipment consisting of intake and exhaust ventilators, 

 exhaust fan and control equipment has been provided so that advantage 

 may be taken of the effect of cooler outside air when the temperature 

 inside the buildings rises to about 90° F. Consideration was given to 

 the direction of the prevailing winds in locating these units in the 

 building walls. The room side of the intake ventilator unit is equipped 

 with a spun glass filter. These ventilators are equipped with rigid 

 and movable louvers. The movable louvers are actuated by solenoids 

 which are connected to the exhaust fan control which functions by 

 means of a thermostat and a differential temperature control. The 

 latter includes outside and inside temperature compensating elements. 

 The thermostat is set at 90° which, with the differential feature of the 

 control, will cause the louvers to open and the exhaust fan to start 

 only when the inside temperature is more than 10° above that prevail- 

 ing outside the building. When the inside temperature has been re- 

 duced to within 10° of that outside, the control circuit is opened to shut 

 off the fan and close the louvers. 



