NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2014 Jan 22, 00:55 -0500
Hi Bill
In Richard Dunn's book (Sextants at Greenwich....) a description of the C. Plath mechanism is given right next to the Heath Hezzanith mechanism.
As expected, they are different. The difference is in the manner in which the tangent screw is detached and attached.
In the C Plath device, a spring loaded trigger is pulled towards the observer to release the tangent screw. In the Heath device, a lever is squeezed sideways.
So the patent is for the specific mechanism of detaching the tangent screw, not for a detachable tangent screw.
Brad
Don and Brad,
A tiny point: lines 11 to 15 of the patent application seem to be referring to C Plath's arrangement, which appeared around 1907 and was not patented.
Bill Morris
Pukenui
New Zealand
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