Page:Popular Science Monthly Volume 70.djvu/239

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hinge for the little tip-up jacks, that connect the line with the brass plate on the bottom of the groove. The spring allows the post to give a little, thereby making a rubbing connection and holding the jacks firmly in their place when any two are tipped up on the same groove to make connections.

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

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:

On the subscriber ringing his bell, the annunciator would fall and the boy-operator would ask: 'What do you want?' Finding out what was wanted, the boy would notify the switchman what connection was desired, which was made by two single plugs attached to a single cord, by placing one of the plugs under each of the jacks requiring the connection.

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