A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2016 Mar 16, 18:31 -0400
Thank you David. Your references clearly state two spirit levels.
Which makes that other diagram sadly lacking in accuracy.
Brad Morris you wrote: Hello David I've always had a great deal of curiosity about the Countinho Sextant. Thank you for that diagram. It explains the optical path using the auxiliary mirror quite plainly. The bubble in the single spirit level is reflected off of the aux mirror. Does the smaller horizontal aperture provide an unreflected, direct path to that same bubble in the same spirit level? Or is there an additional spirit level not shown in the diagram? Thanks! Brad
Hello Brad. I must admit I hadn’t considered that the lateral view might be of the same spirit level as you suggest. As the altitude measuring level is a lengthwise tube in the direction of viewing, I think not.
I just checked Ifland to make sure. The diagram (fig 172 below) in Peter Ifland’s book shows a ‘Hohenlibelle’ (high dragonfly ???? according to Google Translate) and a separate ‘Querlibelle’ (transverse level). Fig 171 (below) also mentions two levels. DaveP
(Ifland-Fig172.JPG: Open and save)
(Ifland-Fig171.JPG: Open and save)