Hey guys. p-toad was asking about some levels which appeared in a recent post of mine,they were in the pic because that's where I keep them. They are nothing unusual but I think this one is. I got it 2 weekends ago at our semi annual antique fair. It's marked as
THE AMERICAN COMBINED LEVEL AND GRADE FINDER
PATENTED AND MANUFACTUREDBY
EDWARD HELB RAILROAD PA.
US Pat 764809 July 12 1904
Canadian Pat 90643 Dec 20 1904
The first pic is a side view, second is a top view, third is a view of the bottom showing the viewing tunnel and the fourth is a close up of the gravity angle indicator, I'm thinking the way it works is; you first determine the grade or angle you want and prop up or shim the level until you reach the required degree. If you look at the top view you will see a site glass to the right of the compass, when you look down thru that site glass there is a mirror at a 45 % angle which projects your view out thru the tunnel.I had a look on DATAMP and gives some clearer info on the level. I don't know what all the other marking are for on the angle indicator. Need to do some more research.