NATURAL HISTORY BUILDING 97 



is arranged to receive paper dial sheets, one for each day, on "which 

 the signals are marked by a recording point so as to indicate both 

 time and number of station. The stations consist of boxes embedded 

 in the walls and covered by a plate pierced with a small hole for 

 a key, which, being inserted and turned, rotates an armature that 

 transmits a current to the clock. The power is furnished by mag- 

 nets, no batteries being required. While the clock has sufficient 

 capacity to record from 50 stations, only 33 stations have been 

 installed. They are distributed to the most remote parts of the 

 building, seven being located in the ground story, six in the first 

 story, seven in the second story, eight in the third story, and five in 

 the attic. 



Time clocks. — Time is furnished throughout the building by a 

 series of marble clock dials, the hands of which are controlled elec- 

 trically by a master clock in the office of the superintendent of con- 

 struction and labor. There are sixteen of the subsidiary dials, one in 

 each of the large exhibition halls, six in the ground story and seven 

 in the third story. A Seth Thomas eight-day clock of superior qual- 

 ity, placed in the telephone exchange room and corrected at noon 

 each day through electrical connection with the Naval Observatory 

 in Washington, supplies the standard time by which this service is 

 regulated. 



Telephone semnce. — The telephone exchange for the entire Museum 

 service is installed in a room adjoining the north entrance lobby and 

 the office of the watch, which obviates the necessity for the presence 

 of a regular operator after the close of business hours. The switch- 

 board is known as the Western Electric Company's No. 4 private 

 branch exchange, and represents the latest type of common battery 

 equipment, with small electric lamps as signals. Its total ultimate 

 capacity is 240 local telephones, 40 trunk lines to the central office 

 , and 30 pairs of cords, the equipment being divided between two oper- 

 ators' positions. Only one position has been fitted up, with provision 

 for 120 telephones and 8 trunk lines, and a complement of 15 pairs 

 of cords. The number of telephones actually in use is considerably 

 less than tJiis, however, and the number of trunk lines is limited to 5, 

 one of which belongs to the departmental service. 



The cables enter the building below ground level at the west side 

 of the north pavilion where the exchange room is situated. They 

 pass through the western tunnel under the middle wing to the north- 

 west corner of the south pavilion, and thence to the attic in which 

 they foUov/ along the walls of the three wings. The branch station 

 wires for the instruments in all stories run from the cables in the 

 attic. A specially designed picture molding in the ground and third 

 story rooms provides the means for their extension along the walls. 

 80120°— Bull. 80—13 7 



