Hi Doug,
If you drop a line to Roger Davis at "Roger's Optics & Restoration" here
in Sydney, he may also be able to add something to the narrative previous
posters have kindly provided.
Contact details -
http://www.rogersopticsrestoration.com.au/contact.html
Roger is a historical binoculars aficionado and the go-to guy if you ever
consider having them professionally restored.