NavList:

I ran across Sight Reduction Tables for Sun, Moon & Planets – Thomas D. Davies – 1982 on eBay and didn't recognize the publication. Searching NavList for Davies brought up one mention by Bruce Stark referencing a 2001 post that I couldn't get to. Searching online for the author brought up a very interesting https://www.starpath.com/foundation/AdmDavies.htm 

Impressive.

About halfway down the Starpath article, it mentions the Sky Compass with "a set of polarized lenses mounted in a frame that penetrated the top of the aircraft. By rotating the lenses, an accurate relative bearing of the sun could be made while the sun was still well below the horizon. By using this relative bearing and the known longitudinal position of the sun, taken from the Nautical Almanac, the gyro compasses could be accurately realigned. This procedure allowed the aircraft to navigate in polar regions where all other compasses of that time were useless. Magnetic compasses could not be used and gyros compasses precessed to a degree that they were utterly useless unless frequently corrected. For this necessary and useful invention, Commander Davies, received the Thurlow Award for the Outstanding Contribution to the Science of Navigation for 1949 from the Institute of Navigation."

That sounds like the Viking Sun Stone.

Yes: https://www.gi.alaska.edu/alaska-science-forum/polar-navigation-and-sky-compass Searching eBay and online don't find a physical Sky Compass to go with the hundreds of sextants and occasional Sun Compass offerings.

Spoiler alert: The tables on eBay are apparently the Concise Sight Reduction tables. The 1982 presentation of, and claims for, the 1974 tables are very enthusiastic. Searching NavList for "Concise" is very productive.

Regards, Noell