NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Art Leung
Date: 2022 Jan 24, 06:47 -0800
The Bygrave/MHR1 cylindrical slide rules were WW-II era devices. I wrote up an article on Bill Morris' sextantbook.com that describes a reproduction that Bill had made (using data files and materials found here on NavList) which can be found here: MHR | Search Results | The Nautical Sextant (sextantbook.com)
If you have not seen these articles, I highly recommend them:
PositionLineSlideRules.pdf (rechenschieber.org)
Collecting_DennertPape_HR.pdf (rechenschieber.org)
You will find that real MHR1s will come on sale on eBay but be prepared to spend a lot of money to get one.
There was a Poor's Line of Position Computer that recenty came up on eBay: Line of Position Computer Mechanical Navigator For Ships and Aircraft | eBay
If you look up "Flat Bygrave" here on NavList, you will also find the means to easily create a flat version of the cylindrical Bygrave.
-- Art
