Two men testing for bad joints in the railway. One man holds metal poles a and b three feet apart. Wires are connected to the poles that lead to the box the other man is holding. There is a bell inside of the box which will not ring when a current is running through it. When the phone makes a noise, there is a bad joint present.
finding bad joints, how to find bad joints, how to find joints in a railway, is there another use for a telephone other than calling people, other uses for a telephone, railway joints, what are other uses for a telephone
International Correspondence Schools A Textbook on Electric Lighting and Railways (Scranton, PA: International Textbook Company, 1901)
Courtesy the private collection of Roy Winkelman