TelephonesIt's common practice in England to ring a telephone by sending extra voltage across one side of the two wire circuit and ground (earth in England). When the subscriber answers the phone, it switches to the two wire circuit for the conversation. This method allows two parties on the same line to be signaled without disturbing each other.
Anyway, an elderly lady with several pets called to say that her telephone failed to ring when her friends called; and that on the few occasions when it did ring her dog always barked first. The telephone repairman proceeded to the scene, curious to see this psychic dog.
He climbed a nearby telephone pole, hooked in his test set, and dialed the subscriber's house. The phone didn't ring. He tried again. The dog barked loudly, followed by a ringing telephone.
Climbing down from the pole, the telephone repairman found:
- The dog was tied to the telephone system's ground post via an iron chain and collar..
- The dog was receiving 90 volts of signaling current.
- After several such jolts, the dog would start barking and urinating on the ground..
- The wet ground now completed the circuit and the phone would ring..