I have a little collection of them. I keep the small Hemmi bamboo on the navigation table at all time. https://wiki.xxiivv.com/site/slide_rule https://wiki.xx

I have a little collection of them. I keep the small Hemmi bamboo on the navigation table at all time. https://wiki.xxiivv.com/site/slide_rule https://wiki.xxiivv.com/site/slide_rule