NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Bubble sextants on e-bay
From: Douglas Denny
Date: 2009 Jun 6, 15:35 -0700
From: Douglas Denny
Date: 2009 Jun 6, 15:35 -0700
Correction: The Fairchild has a thin lead washer of lead wire in a circle and crossed-over at the join - underneath the glass lens, acting as a maleable seating; with a thin brass shim washer on top pressed down by the slotted screw ring. Squashing the lead it with the glass lens under pressure makes the seal. The link has the glass lens (which has a tapered edge uppermost) sitting in a seating with some shellac or other material which has become a hardened brittle material on the glass edge in the seating; and a large, thick lead washer on top which is compressed by the slotted ring into the tapered glass lend edge and threads. It seems Link did not want any leakage under any circumstances as they went in for overkill here. The lead washer had to be cut away as it had become squeezed into the space of the tapered glasss lens and thread area. Hydraulically pushing it out with pressure from inside is clearly the best option. Will do that next time I come across one. Douglas Denny. Chichester. England. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---