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    Re: Why is a sextant like it is?
    From: Trevor Kenchington
    Date: 2004 Nov 17, 20:38 -0400

    Interesting question.
    I'll take a guess that the common layout of the sextant was based on
    that of Hadley's quadrant, which itself was primarily intended for Sun
    sights, for which the convenience of looking horizontally outweighs
    other considerations. If so, your question could be re-phrased as: Why
    did the form of sextants not evolve to make them easier to handle for
    lunars and for star sights?
    The star sights may be easily answered: If most mariners pre-computed
    their twilight sights, inverting the sextant to find a particular star
    will have been too unusual to merit a major re-design of the instrument.
    That leaves lunars, for which I have no such simplistic answer. Reading
    the on-running threads amongst the "lunartics" on this list, I am often
    left trying to visualize navigators, at sea under sail, contorting
    themselves in an effort to get highly-precise measurements of distances
    between awkwardly-placed celestial bodies, half-obscured by sails and
    rigging and I just can't picture that. I would expect that memoirs of
    the time would mention the awkward observations but I am not aware of
    any that do. Is it possible that the rare lunar observations (and we
    know they were rare) were normally only made when the required distance
    could be measured _without_ awkwardness?
    Trevor Kenchington
    Trevor J. Kenchington PhD                         Gadus{at}iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
                         Science Serving the Fisheries

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