From the “vertical side” of the intermediate frame Mrs. Smith’s wires reach the “line and cut-off relay,” an electrically controlled switch which turns on the light signal that appears on the switchboard when she lifts the receiver from the hook. This “line relay” also extinguishes the light when the operator makes the connection, or when Mrs. Smith returns the receiver to the hook. [Illustration: A TYPICAL POLE LINE, WITH CROSS ARMS, IN THE COUNTRY] The swift moving electric current that was set in motion when Mrs. Smith began the call, instantaneously passes through all these devices for safeguarding and protecting the subscriber’s telephone service. The light announcing Mrs. Smith’s desire to make a call is called the “line lamp,” and is flashing on the switchboard. Directly beneath it is the “pilot lamp,” which glows whenever any “line lamp” lights. With the “line lamp” is a “jack” or terminal, where connection can be made with Mrs. Smith’s line. This is the “answering jack.” [Illustration: THE CABLE VAULT INTO WHICH THE CABLES PASS WHEN THEY ENTER THE EXCHANGE AND FROM WHICH THEY ARE LED UPWARD TO THE MAIN DISTRIBUTING FRAME] When the operator sees the flashing signal of Mrs. Smith’s “line lamp,” she inserts one end of a pair of “connecting cords,” which are on the board before her, in the “answering jack” for Mrs. Smith’s line. These “connecting cords” are flexible conductors that put the wires of subscribers in electrical connection. Then she pushes forward the “operator’s key” directly in front of her and is connected with Mrs. Smith’s line. The operator ascertains the number wanted and places the other “connecting cord” in the “jack” corresponding to Mrs. Jones’ line. If she finds she cannot herself connect with Mrs. Jones’ “jack,” because it is on another part of the board out of her reach, she makes a connection with another operator who can reach Mrs. Jones’ line. The second operator then makes the connection with Mrs. Jones’ “multiple jack” and places her line in connection with Mrs. Smith’s line at the first operator’s position. At the same time the first operator pushes the operator’s key back, thus ringing Mrs. Jones’ bell. “Supervisory lamps” on the board before her, connected with the “connecting cords,” tell the operator when Mrs. Jones answers the summons. They flash when the connection is made and one goes out just as soon as Mrs. Jones takes the receiver from the hook to answer. If one of these lamps flashes and dies out alternately it tells the operator that either Mrs. Smith or Mrs. Jones is trying to attract her attention and she connects herself and ascertains the party’s wishes. When both subscribers “hang up,” both lights flash to indicate the end of the conversation. The operator then disconnects the cords from the subscribers’ “jacks” and presses the “message register” button recording the call against Mrs. Smith. [Illustration: ROUTINE OF A TELEPHONE CALL