Cylindrical Slide Rule MHR1 Höhenrechenschieber (FLITEC172)

This is a very rare WWII-era computational device developed and used in Germany. 

According to collector George Fulford's notes:

To many collector of slide rules, not only those like myself who concentrate on those specific to air navigation, this German masterpiece was the Holy Grail of our search. This is the first I’ve seen come on sale and the bidding for it was tempestuous and I was determined to own it and – at great cost – I was victorious. 

. . . the original design was an RAF Bygrave that was developed in the 1930’s specifically for flight celestial navigation. Francis Chichister used one in his round the world sail in the “Gypsy Moth”.  It was a brilliant design, and as usual the Germans grabbed it and perfected it. The Japanese also made a copy but based on the German design. The Bygrave is more than rare, just the odd copy in a museum here and there. The Japanese ones has been on the web a coupe of times but sadly I only found out about it after they were sold.

I’ve got some very distinguished items in this heterogeneous aviation collection but, here it is: The very best rare item in the whole collection!