| MadSci Network: Engineering |
Answer:
I believe that there were both batteries and DC hand-cranked generators available at that time.
The gravity battery is actually a form of electrochemical cell used to provide a source of electrical power for the telegraph. By the early 20th century, most telegraph lines were powered by motor-generators, however, the gravity battery continued to be used in way stations to power the local circuit. This practice continued at least into the 1950s. The gravity battery used a zinc and a copper electrode. The zinc electrode is seen hanging from the top of the jar. It is often called a "crow's foot" due to its design. A copper electrode is positioned at the bottom of the jar, and is connected to the circuit with an insulated wire. The term "gravity" is used since the solutions of copper sulphate and zinc sulfate have different densities and seperate like a mixture of oil and water. Solid copper sulfate or "bluestone" is added to the copper electrode at the bottom of the cell. The copper sulfate is slowly depleted in use. More copper sulfate is added to refresh the cell.
Check out the following: http://www.cris.com/~Gsraven/index.shtml
Gus Calabrese