NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: How does the AstraIIIb split mirror work?
From: Robert Eno
Date: 2004 Apr 26, 16:31 +0100
From: Robert Eno
Date: 2004 Apr 26, 16:31 +0100
I have been following this discussion off and on and confess that I have not been paying it close enough attention. With that in mind, perhaps one of our more erudite members (do you hear me George?) can provide a summary of the supposition, observations and conclusions that have transpired over the past few weeks. I'd like to add here that I am not a big fan of the split horizon, which has been the subject of much discussion. I switched to a whole horizon years ago and have never considered going back. Having been an avid celestial navigator for over 20 years, my preference flies in the face of the commonly-held view that "beginners" prefer the whole horizon, while "experienced" navigators prefer the split horizon. I have used the whole horizon under various conditions of light and weather at sea and on land and never felt hindered in any way (maybe I am just too stupid to know better?). Having said that, I use my sextant extensively with an artificial horizon for practice on land, which may have a lot to do with my preference. Whole horizon mirrors seem to lend themselves to artificial horizons (both bubble attachments and external reflective) much better than split horizons. In the end, I think it is a matter of what works for the individual. Robert >This matter of how light arrives at the eye via the unsilvered surfaces of >the index mirror now seems to be resolved, to (at least) Ken Muldrew's >satisfaction. Others may yet find a scrap of meat remaining on the the >bone, to pick at. > >To me, it seems to have shown all the best features of how a mailing-list >discussion ought to be conducted. Listmembers proposed various experiments, >tried them out, argued about the results, argued about the underlying >principles, tossed various ideas to and fro, in a spirit of courtesy and >mutual respect, to reach a conclusion. > >"Well, he would say that, wouldn't he?" I hear you say, because my original >suggestions were confirmed. But I think that all on this list are >open-minded enough to be prepared to change their stance, and their minds, >in the face of strong-enough evidence and argument that points another way. > >It's a real privilege to be a member of such a list as Nav-L. Thanks to Ken >for raising an interesting question. > >It leads me to wonder how quickly and successfully science and >understanding would have progressed, in the Days of Newton and Maskelyne >and Sumner, if they had been able to argue with their contemporaries by >email, instead of sending letters carried by packhorse and sailing ship. > >George. > > >================================================================ >contact George Huxtable by email at george@huxtable.u-net.com, by phone at >01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy >Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. >================================================================ ------------------- Email sent using AnyEmail (http://netbula.com/anyemail/) Netbula LLC is not responsible for the content of this email