Portable direct-reading traffic recorder

The average number of simultaneous calls in progress on a group of selectors is equal to the number of traffic units carried by the group. The device described consists of pulse-driven ratchet switches which connect meters to groups of switches and register the total number of circuit engagements in a repeated test cycle. The basic cycle of 50 steps every 10 sec is repeated for 1 hr and the meters thus read the traffic directly in terms of 100-sec calls.