NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Star-star distances for arc error
From: Frank Reed
Date: 2009 Jun 26, 21:16 -0700
From: Frank Reed
Date: 2009 Jun 26, 21:16 -0700
Jim, you wrote: "As noted, readings to 0.1' can be done without a vernier, so why have one?" Marketing! :-) Users like them and expect them, whether for rational reasons or not. Just about four years ago, I wrote: "I've also noticed that some Plath sextants don't include a little vernier scale for reading off tenths of minutes. But in practice, I find that this matters relatively little." And Joel Jacobs, who sells sextants, had replied: "Thank you for saying that. Some people think they are getting short changed when there is only the index and no hash marks. It should make no difference since you can visually estimate with great accuracy the intermediate reading." And seriously, he had a nice Plath sextant, if I remember correctly, that was turning off some customers because it didn't have that little micrometer vernier. -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---