A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2014 Dec 4, 10:10 -0800
Hanno. Just when your friends think they’ve got it sorted out, introduce bubble size into the argument. It’s easier to judge the centre of a tiny bubble, but it seems to be less responsive than a large bubble. It’s probably due to some sort of square/cube law between volume and surface area. I seem to remember being told the ideal bubble had a diameter 2/3 of the distance between the tramlines, or was it 1/3 of the distance? We always tried to grab a pendulous reference model, which had a pendulous mirror on a quartz thread instead of a bubble, and a London Underground Sign to aim with. Then you didn’t have to worry about making a suitable bubble.