NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Why a pentaprism?
From: Geoffrey Kolbe
Date: 2022 May 29, 21:42 -0700
From: Geoffrey Kolbe
Date: 2022 May 29, 21:42 -0700
I suspect the key to your question is the fact that this is a 'surveying' sextant.
When plotting survey lines of an area and you meet an obstacle around which you would like to traverse, a device that allows you to lay out a right angle off a particular survey line is very useful. There are a number of survey devices that allow the surveyor to do this. I suspect the pentaprism on this instrument adds this facility to the sextant.
