Next message: Herbert Prinz: "Re: Maskelyne"
------------------------------------------------------------------------
Frederick V. Hebard, PhD Email: mailto:
Staff Pathologist, Meadowview Research Farms Web: http://www.acf.org
American Chestnut Foundation Phone: (276) 944-4631
14005 Glenbrook Ave. Fax: (276) 944-0934
Meadowview, VA 24361
On Dec 7, 2003, at 10:13 PM, Frank Reed wrote:
> Bruce Stark wrote:
> "In the way we work our lunars you and I are at different ends of the
> spectrum. I do everything the old way, not even graphing or plotting.
> I find it satisfying to work observations the way the old navigators
> did."
>
> I haven't been able to descibe all the approaches I've experimented
> with in the brief time I've been on this list. I may have given the
> impression that I'm in favor of computer solutions for lunars, but
> that isn't the case. There are many options.
>
> And:
> "But this approach is not going to take the world by storm. Most
> people shy away from anything that calls for a skill they don't
> already have, and the present generation has no skill at
> pencil-and-paper calculation. They've had no reason to develop it. The
> recruitment that will keep sextant navigation alive (and perhaps help
> put the history of navigation on an honest footing) will almost
> certainly come at your end of the spectrum."
>
> Anyone interested in celestial will eventually try the paper methods,
> and since it is no longer a "practical" art, I think it's very likely
> that more students will want the historical techniques instead of
> electronic approaches and also they will likely bypass mid 20th
> century methods like the highly refined H.O. tables.
>
> There are a number of reasons why we need computer solutions for
> celestial navigation alongside the paper methods:
> 1) Some celestial enthusiasts really have no interest in the
> calculation. They want to see themselves handling a sextant, learning
> to take sights with skill, but the reduction is somebody else's
> problem. Those people are part of the market, so I don't disdain their
> preference.
> 2) A quick reduction with a few dozen strokes on a keyboard (or a cell
> phone!) means you can take many more sights. Practice makes perfect,
> and you can practice shooting lunars anytime when you get instant
> feedback from electronic reduction.
> 3) When you have a computer solution, you can do a ten-minute
> introduction to lunars for students, friends, etc. They can see it in
> practice and quick. Then those who want to can learn whatever paper
> method suits them as time and interest permit.
>
> You also wrote:
> "The only thing I take exception to is the idea that navigators had to
> have a chronometer to see them through the four days or so of the dark
> of the moon. Dead reckoning saw them through. Dead reckoning gave the
> continuity the chronometer provided for later generations. The purpose
> of nautical astronomy was simply to correct the reckoning now and
> then. That kept it from drifting dangerously far from the truth as the
> weeks and months went by."
>
> What I was getting at though is the next step beyond dead reckoning.
> Yes, dead reckoning saw them through, and it's good enough to sail
> around the world. It's what Slocum used for longitude as late as the
> 1890s (plus one lunar distance). But accurate navigation is founded on
> one simple thing: money. It's all about money. A ship that had
> accurate longitude approaching a coast at New Moon could sail with
> confidence and speed and get its cargo to port ahead of its
> competition. DR was a start, but to beyond that they needed lunars AND
> chronometers.
>
> By the same argument, for most smaller vessels, there was more profit
> to be made by accepting a little risk and relying on dead reckoning
> alone for longitude instead of spending money on a superior sextant
> for lunar distance observations or, even more pricey, a chronometer.
>
> And why is celestial navigation almost over and done with today?
> Because of price. When the price of two GPS receivers fell below the
> price of one sextant, the show was over.
>
> Frank E. Reed
> 75% Mystic, Connecticut
> 25% Chicago, Illinois
>
>
