I bought this from Jamie Houdeshell. I've wanted one for a while.

So what is it? It's a Postal Telegraph call box. It was located in a customer's office and connected to the Postal Telegraph office by a dedicated circuit.

It works similarly to a fire alarm call box. It has a spring-operated motor and a set of contacts, with a code wheel that operates the contacts.

When the handle is given a quarter turn and released, the motor operates the contacts, sending the unique code to the local Postal Telegraph office. This alerts a messenger to come to the customer and pick up a telegram.

This one has three terminals. Only the right-hand two seem to do anything. When I turn and release the handle, the normally open contacts close and open, sending the code.

I opened it up to see what the function of the third terminal is. See [id=294456076].