THROWDOWN MACHINE FOR TRAFFIC STUDIES 



347 



ing a release time. The trunk number and release time are recorded. 

 At the end of the holding time, the operator removes the line peg or pegs 

 from the trunk jacks and the pegs are returned to their home jacks. 

 Presence of the Une pegs in the trunk jacks during holding time marks 

 the trunk busy. 



The busy trunk numbers are recorded in a holding time book according 

 to release times. Time units in the system represent millionths of an 

 hour (0.0036 second). Each page of the holding time book covers 10,000 

 units of time and is divided into one hundred 100-unit blocks. An illus- 

 tration of one page of the book is sho^^Tl on Fig. 22. 



Since the time unit is one millionth of an hour, each time unit in a 

 one houi' series can be represented by a six-digit number. Of these six 

 digits, as far as the long holding times are concerned, the last two are 

 unimportant since 100 units is only 0.36 second. If they are dropped, 

 the first two digits of a four digit holding time release figure give the 

 10,000 time unit group or page number of the holding time book and the 

 second two digits give the 100-block on the page. Trunk numbers are 

 entered in the book on this basis with the page and block number ob- 

 tained from the assigned holding time counter. 



By this means the release times of all items appear in consecutive 

 order in the holding time book. Holding time entries are always made 

 several 100-blocks beyond the next release time, which eliminates con- 



Fig. 22— Holding time book. 



