The combined annunciator recording drop-plate shown on this Snell board is of interest in showing the appreciation in those pioneer days of the necessity of a measured-service system. Five falls of the plate (Fig. 14) would cause one revolution of the shaft, which, in turn, would move the indicating wheel one notch. A later form of switchboard
Fig. 14. | Fig. 15. |
devised by Coy and Snell is shown in Fig. 16. A board of this type was installed in Hartford in 1879. In December, 1881, in the Providence exchange there were thirteen Post-Snell switchboards of twenty-five wires each, four of fifty wires and one of sixty wires, arranged on three sides of the operating room, and from these eighteen boards service was supplied to eleven hundred subscribers.
The switchboards adopted by other exchanges were as unique in character as those erected in New Haven. In St. Louis, in April, 1878, Mr. George F. Durant used a 'jump jack switchboard,' the operation of which is thus described:
The second switchboard had brass bars running the entire length of the board, with holes about every five or six inches to insert the plugs