NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Dip of the horizon
From: Alexandre Eremenko
Date: 2004 Nov 15, 20:08 -0500
From: Alexandre Eremenko
Date: 2004 Nov 15, 20:08 -0500
As I understand, the dip of the horizon is the most important factor that limits the precision of measuring altitudes. (I include refraction of the horizon to this). In the Russian navigation book I read in my youth, a special device for measuring this dip was frequently mentioned. It was called "naklonomer Kavraiskogo" (phonetic transliteration). Kavraiskii is a name, apparently some expert/inventor in navigation, I see this name sometimes attached to various Russian devices. The word "naklonomer" has literal translation "dipmeter". I have no idea of what this device looked like, or on what principle it worked. I've never seen it on e-bay, for example. (First I thought that this is translated as "clinometer", but then after having seen several "clinometers" on e-bay I concluded that this is not so). The book made an impression that measuring the dip with "naklonomer" was more precise than using the dip tables. The only principle I can imagine is some "bubble arrangement", but I always wondered why did they have a separate device, rather than the usual bubble attachment to the sextant. Apparently this was something much more precise than the usual bubble attachment to a sextant. (I suppose the usual bubble attachment gives worse results than the natural horizon under normal conditions. On the other hand, the Russian book recommended to "always check the dip with "naklonomer" whenever possible, and to obtain high precision"). Did any analogous devise exist in the West? How was it called then? How did it work? Alex.