Copyright © 1997, Neal McEwen
I perceive that this galvo is a little more advanced than what would be found in a high school or college physics laboratory. I would be interested in your opinion.
The galvo was made by "Gambrell Bros., London" as can be seen from the inscription below the window. The cylinder is 5" in diameter and 4 3/4" high. The entire unit, from the feet to the top of the tower is 10 1/2" high. The galvo is very heavy, 8 1/2 pounds; this is due to a permanent magnet that conforms to the shape of the can. The edges of it are barely perceptible through the window. There is a coil suspended between the poles of the magnet and it is connected to the two terminals and has a resistance of 3,000 ohms. Attached to the coil is a small mirror. The coil / mirror assembly seem to rest on the floor of the cylinder and turns about the vertical axis. There is no evidence of a thread or silk suspension system.
There is no apparent way to get inside the galvo. It appears as though a can opener would be required to get inside.
Can any clues be derived from the markings? Is "H 943" an inventory number? Could "C5" denote that this galvo was used on "Cable #5"? Mirror galvanometers were used on the receiving end of submarine telegraph cables. I wonder if this galvo was used at a cable station. What other applications required a mirror galvanometer?
If you can shed any light, whatsoever, on this handsome little device, please email me at the address shown below.