It is an old aircraft
compass, mid 1940s to mid 1950s, B29, stratocruiser, etc. Designed so it can be installed at a right angle to course, but show course. Compases like this were installed in the navigators compartment above the chart table. The navigator would sit facing the side of the cabin and the
compass would be in front of him. All of the ajustment
wheels let you level the
compass. The big plate at the bottom is a damping plate to slow the
compass and prevent jump. If the plate at the bottom has electrical connections then it could be a reapeater
compass, but from what I can see of the picture I don't think so.
Cheers,
Todd