Computer, Line of Position, c 1917 (FLITEC052)

This 15-inch-diameter metal flight computer has been mounted on a wooden base and framed for display. 

According to collector George Fulford's notes:

I’ve introduced this one now to break up the monotony. This piece is right up there with the rarest of the rare. I found it in a posh antique shop in San Francisco forty odd years ago and paid a small fortune for it because it was mounted on a stained wooden base and framed and looked just special, as it still does in my study.
First, it’s a big one, fifteen inches across and it is essentially one big circular mathematical slip stick, except the trigonometric numbers are all hooked up to solving the celestial equation from a sextant shot. Famed Captain Weems – who published first class books on air navigation before the war - thought it was too big to use in flight. But a lot of navigators did. I’ve been told, though not verified, that Alcock and Brown used it when making the first transatlantic flight in 1918 on a Vicker’s Vimy. I’ve read of other less well renowned trips. What it amounts to is that this computer is, as far as I know, inadvertently, the very first air navigation computer ever made even though it was only used for celestial work.