Let’s look "overhead" to see how a telephone was connected to the outside world.
Starting with the wall-mounted telephone, the two-wire line (designated as “tip” and “ring” to correspond to a switchboard plug) would pass through a “protector” box.
Inside this box is a carbon spark gap to provide protection if lightning should ever strike the telephone line. There are also two fuses inside the protector box to provide protection if a power line falls onto the telephone line. This is very important—even today, many telephone poles share space with power lines. Similar protector boxes are still used today.
Above the protector box, the wires continue up the side of the house. How far up they go depends on the height of the building and the height of the telephone wires. The drop wire connects the customer’s home or office to the telephone wires strung between the poles. From there, the telephone signal goes down the street to the telephone office.
The size and complexity of the local telephone office (sometimes called the central office) varied a great deal. In large cities, the central office was quite large, serving thousands of subscribers. In smaller towns, a small central office was common. In more remote areas, the telephone office was nothing more than a magneto switchboard in a private home or small office.
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