8A Bunnell's"Giant Sounder" was originally patented in 1875. That was what we now consider a typical old-style sounder. It has instrument posts for the connecting wire, knurled lever pivot screws and locknuts, and a heavy brass plate.
In Contrast, this improved model has Western Electric style clamping posts, simple pivot screws and a thin baseplate. Although it lost the character of the earlier style, it was undoubtedly a better sounder.
8B At first glance it looks like a common sounder, but this "repeating sounder" has a pair on contacts between the lever and the stop standard. Notice the insulator under each leg of the stop standard, and the contact circuit connectors on the left side of the base.
Very long telegraph lines are broken up into sections, each section powered by a reasonable number of batteries. So that messages can be sent from one section to the next, in either direction, a "repeater" is necessary. There are many designs using the electromechanical instruments. One design is the Atkinson repeater. It uses two relays , two transmitters (sounders with two-way contact breakers) and two repeating sounders.
Back | Next