A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Sean C
Date: 2020 Aug 18, 02:28 -0700
R William McAllister wrote:
"... we also learned how the "clocking" of the Chair of Cassiopia relative to the 'pole' star might be used to determine an approximate correction to the observed 'latitude.'"
The "nocturnal" that I mentioned earlier has a set of scales on the reverse side which are exactly for this purpose. (See attached pic.) The inner scale is for the "Great Bear" (Dubhe in Ursa Major) and the outer for the "Little Bear" (Kochab in the Ursa Minor). You look at Polaris through the center hole and align the arm with either of those two stars, then read off the correction from the appropriate scale.