THROWDOWN MACHINE FOR TRAFFIC STUDIES 



315 



complex units of the system, such as markers. The gate provides a means 

 for operators to feed traffic into the machine and determines the order in 

 which each working item of traffic is taken up by the control circuits. 

 The RANDOM CIRCUIT is an electronic ''roulette wheel" which permits the 

 operators to make random choices in disposing of certain traffic items. 

 It provides random selections varying from one out of three to one out 

 of ten. 



The individual record of each call is made on a card of the form shown 

 in Fig. 9 which is called a ''call slip." These are of various types identified 

 by distinctive designations and colors for the several varieties of calls 

 which may occur. The basic types are: dial tone, intra-office, incoming, 

 and outgoing. 



As the call progresses through its various phases the slip is passed 

 from one operator to another, each operator retaining the slip while it 

 is in the phase mider her control and recording on it in designated spaces 

 the nature and time of the events taking place. When the call is com- 

 pleted, the shp carries a complete record of the call including the designa- 

 tion number and time of seizure of the various circuit units used in estab- 

 lishing the connection and the nature and duration of any delays 

 encountered. 



GATE 



CONTROL 

 CIRCUITS 



STOP- START 



TIME 

 DETECTORS 



TIME PULSES 



CLOCK 



Fig. 8 — Communication between the machine components and the operators, 



