NavList:

Iv'e just heard from David Burch at Starpath that John Luykx sadly died in 2003.(http://www.legacy.com/obituaries/washingtonpost/obituary.aspx?n=john-marie-luykx&pid=1357884.

Davis Burch has no knowledge of the Brown-Nassau and recommended Navlist as the most likely source of information!

I do not know whether this interesting device ever made it into protype production, but from the Luykx's article, it looks as if he must have had one to do the experiments where he was getting Hc's within a mean error of 2.6' and it would appear to take less then a  minute to do.(i.e possibly faster and easier, but not quite as accurate as the Bygrave). It was being tested at the Naval Air Experimental Station, Navy Yard, Philadelphia from January-June 1944.They apparently produced a report on 29th August 1944 stating "Considisered as a whole, this is the first device tested warranting very extensive testing in small airplanes"

I wonder whether anyone knows anything about this or where I could locate diagrams/scans of the original in order to construct a copy.This looks to be the only viable non elctronic competitor to the Bygrave.

Best wishes