Calculagraph

A description of an ingenious machine for the use of telephone operators in recording the time of toll and trunk calls. The driving mechanism is a clock, the dial of which appears between two vertical handles. On setting up a call a card is inserted, and on pulling one of the handles a set of dials is printed with the time of the day and the date. On the completion of the call the operation of the other handle prints arrows which indicate the period of the calls on the dials previously printed.