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    Re: Sun Moon Lunars to 155 degrees
    From: Antoine Couëtte
    Date: 2010 Apr 6, 05:00 -0700


    In reply to the ideas and thoughts I had earlier developped in :

    [NavList 12625] Re: AW: Sun Moon Lunars to 155 degrees
    From: antoine.m.couette---fr
    Date: 31 Mar 2010 04:36

    you replied in your post published in :

    [NavList 12470] Re: Sun Moon Lunars to 155 degrees
    From: FrankReed---com
    Date: 5 Apr 2010 04:38

    Thank you for the time you spent for preparing instructive and detailed replies in reaction to some personnal thoughts I had expressed about :

    - the difficulties of Lunars, or

    - the added potential blunder traps induced by somer former calculation standards ("irregular" Apparent time vs. "regular" Mean Time for example), or even

    - some possible explanation for such a late "arrival" of the LOP method found by Capitaine de Frégate Marcq de Saint Hilaire.


    Some of my thoughts were just personal conjectures and you expressed different view-points such as :


    But there's no use worrying about histories that "might have been"... There's only one history of navigation.


    and further down, with your very last words :


    If you want to understand the history of navigation, look to the papers and notes of navigators.




    First of all, a Forum is certainly an "ideal place" to exchange ideas and confront view-points. We can do nothing here but again thanking you for giving us this unique opportunity.

    We all know that there is not a "single line of thinking" to revive history in a number of areas, so I am remaining short of being convinced that " There's only one history of navigation. "

    While you have well established viewpoints, I actually do not have ... any just from personal historical studies. So I am taking a great interest in trying to understand yours. And I start being attracted by a number of them and as a consequence I am begin sharing and personnally endorsing some of the view points you express. I am concluding that most of your analysis and personal opinions based on your seemingly quite serious study of a great number of Navigation Logbooks you have had access to, all this way of thinking of yours will probably survive the years and decades to come.

    Still, in one particular area ... maybe in 20 or 30 years from now, widely accepted views about the computational difficulties encountered during the 18th/19 th century might still remain quite different from the ones which I can interpret from your own opinions which - here and there - seem to minimize (if not just simply discard) the possibility of any computational difficulties or potential traps encountered by our predecessors. An example of a personal view of yours here ?


    And you wrote:
    "On top of that, just add that - until the 1830's or so - they kept playing with a "non uniform" time variable, i.e. the Apparent Time which had for effect of providing them with so many additionnal opportunities for blunders ..."

    What blunders?? This was no issue.




    While I hear what you say here - as well as such a similar view-point recently expressed by Brad (Thank you Brad !) - in the sense that all these Navigators were superiorly trained and even maybe for some of them had probably (almost) nothing else to do, such as possibly M. William Bayly in the years around 1770/1780, it nonetheless would seem that :

    - Navigation Computations Methods have ALWAYS evolved from DIFFICULT into LESS DIFFICULT or even into (ALMOST) SIMPLE ones, which is our current case for the LOP's computed just from printed Tables. This fact simply means in general that Lunars WERE DEFINITELY (VERY) DIFFICULT in the earlier times - which you did specifically acknowledge in your post - and in particular that :

    - probably still by the time when COOK and BAYLY performed them, after having been "DREADFULLY DIFFICULT" some 20 or 30 years before, Lunars were STILL QUITE DIFFICULT, at least to non-highly trained people. And,

    - to deal with another earlier adressed example, the use of Mean Time vs. True Time was certainly an ease in all calculations and NOT any kind of extra difficulty. Mean Time did benefit from the wider and wider use of Chronometers then. Chronometers/Time Keepers had required so many huge and lenghty efforts, and they just gave indications of the very same nature as Mean Time.

    NONETHELESS ... if calculations with Apparent Time had really been, and even marginally, easier than with Mean Time, all Nautical Almanachs could very well have kept Greenwhich Apparent as a Time Variable - none did - and even if not and in all cases, they would definitely carry to-day one extra DAILY COLUMN with HOURLY VALUES for the Equation of Time (or for its opposite value).


    This simple example of Mean vs. Apparent time in which you almost seem to rule out any potential possibility for extra calculation blunder when compared to our current use of Mean Time (or at least this is the way I understand your view point) brings me to a most important point as follows :


    Getting trained to clear a Lunar from one's Office with Tables and Books can soon and should readily become a piece of cake, not to mention clearing it on a Computer or a "calculator". This becomes super simple and easy once you have fine-tuned your own software into working Lunars and even Lunar Occultations to the expected accuracy under all circumstances.

    Ultimately, and definitely worrying as it might look, one can even split hairs / nit-pick on such points as :


    ... very intense and detailed focus on delta-T, the oblateness/flattening of the Earth, and other such calculational minutiae ...


    ... all this might lead its author "astray", not to mention the very serious risk of leading totally off the right track some Readers.

    To all interested Readers here, and as you all certainly have guessed it, if I ever happen to be personnally concerned by previous descriptions of such kind, I am immediately and definitely pleading TOTALLY GUILTY here.

    BUT ... in Real World, we are not always sitting under clear skies with fair winds and following seas.

    Just put yourself, Frank, into the following situation : a daily total of 12 hours as Officer of the Deck (OOD) - still rather young at the age of 22 or 23 - for 7 and 1/2 weeks in a row under harsh weather (South Indian Ocean), with on top of that your Communications Officer (+ 1 st Lieutenant) regular duties, not to mention frequent Combat Stations. How would you then personnally grade the difficulties in consistently performing and presenting your Commanding Officer with (hopefully) reliable Celestial Navigation Fixes, EACH Morning and EACH Evening ? The very windy weather then enabled us CelNav sights most of time, with the added "ease" that we generally had to take and average sights because, even from a 25 or so foot high observation deck, it was recommended to average sights given the swell induced "irregular" horizon seen from a vessel subject to significant heave.

    The standard "Marcq Saint Hilaire" Celestial Navigation which I always kept loving turned out to be VERY DIFFICULT, if not some kind of a NIGHTMARE, under these times. I always did all computations twice with 2 different reductions methods and tables : at least double time if not triple time for such an otherwise so simple and enjoyable task then to be performed at a much lower pace because of stress and exhaustion. And just averaging 2 and up to 5 sexagesimal degree sights with NO calculator then was just something I hated. I now understand what you recently meant George ... It probably also explains the difficulties I then experienced at correctly reducing MOON Heights, which I no longer encountered some 5 or 6 years later with the use of calculators.

    This simple example just to remind all of us on this Forum that - at times - we might seem minimizing or at least ignoring difficulties encountered when under all kind of operational stressful Conditions.

    It is very easy to deliver knowledge "ex cathedra", and we DO need good teachers in CelNav - and you are certainly one of them Frank - , but just "sailing a desk" might lead into simply overlooking - if not discarting any idea about - the actual difficulties of real operations which all our prestigious or anonymous Navigators could in no way escape from.

    This is why, although most of these Navigators were highly talented and trained, and although - and Thanks be to God - they kept working with on-going improved and easier methods, I personnally would not think that what they did was just "simple" under all sonditions, and that it was quite trivial for them to deliver - day in and day out - whatever their tiredness/fatigues, whatever the weather, the extraordinary and most remarkable results we can contemplate and admire to-day ! Maybe all their Lunars printed results were subsequently "reworked" afterwards before being printed as such beautifully and superbly arranged arrays. This is a possibility that you indicate, but up until now, nothing conclusive here seems to have been fully established concerning these specific 1773 Lunars.

    A last similar example of how fatigue/tiredness can affect your own operational performance ? Just bring your Jet Aircraft at night on board an aircraft carrier. And then ask ANY Navy pilot (only the US Navy and French Navy do it now as routine nowadays, and maybe the Russians soon ?) : do you prefer night traps under clear skies, calm seas with a bright Moonlight BUT while you are very tired (if not exhausted), or do you prefer getting back on-board at night while fully rested and in excellent physical and mental shape BUT in adverse weather and dark nights ? Every single time they will answer (for all the replies I personnally got) : "our chances of surviving - i.e. just saving our ... lives - are far greater if and when we are in good physical and mental condition", which by the way is also just my own personal experience over these many years. Exactly the same thing to-day, although generally much less difficult, to bring a Long-Haul Jet Airliner safely on deck after some 8 to 14 hours of non-stop flying.



    Thinking on an operational standpoint is a view-point which probably could be better taken into consideration among us within our NavList Community.

    Real World Operations under all kinds of weather and in (highly) stressing conditions will eventually force to stay humble and not to underestimate difficulties otherwise viewed as almost non-existent if and when just sitting and tackling them under a totally "soft" environment. Such any "artificial" environment - but nevertheless a REQUIRED and NECESSARY ONE for any necessary early/initial theoretical training (see Chauvenet's early experiences) - can only deliver some very LIMITED operational experience.

    THEORIES, and theoretical views can look just great and even stamped/coined with wisdom, but only OPERATIONAL PRACTICE can and will validate them.

    Just my 4 cent viewpoint here ...

    Best Regards to you all

    Antoine M. "Kermit" Couëtte

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