Rusted, screws missing but working, mechanically speaking. Accurate, maybe but needs restoring either way.
Stamped LCC/London county council, they went the way of the dodo in 1965, so at least that old, maybe as old as 1890. Measurements to follow, along with any more detail found. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "dcbeta" and is located in this country: GB. This item can be shipped to United Kingdom.