Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Pillar sextant: what's in a name? was: Re: Lunar distance accuracy
    From: George Huxtable
    Date: 2007 Oct 25, 12:00 +0100

    I've split-off this threadname here, because this question is interesting
    enough to deserve a topic on its own.
    In the absence of a recognised International Naming Authority, names are
    what people choose to call things by, and ambiguities and inconsistencies
    abound. We have to interpret what people mean as best we can. That is why,
    in doing my best to interpret White's mention of "pillar-sextant", I
    explained both possibilities. I then plumped for the "sextant on a stand"
    option because of the context.
    Frank Reed wrote-
    |  ..You mention that the phrase "pillar sextant" sometimes referred to a
    | sextant mounted on a stand. And I don't think that's true in the first
    | place. I haven't found a single case of this usage in the lit. Do you know
    | of one? As a corollary, is it possible that it's only you (and maybe a
    | museum in Oxford which you mentioned once before) that refer to a sextant
    | a stand as a "pillar sextant"?
    These were rare-ish instruments, intended for use in special circumstances,
    as I explained. I have seen only two examples. One was in the Museum of the
    History of Science, in Oxford. [note in passing: this is what Frank referred
    to as "a local museum", and it is a museum, and it is local, but it happens
    to house one of the World's great collections of scientific instruments,
    with an international reputation]. It had been labelled there as a
    pillar-sextant. That, of course, does not necessarily define its name. It
    was what a museum curator chose to put on its label at the time it went on
    display. He may have done considerable research beforehand, or none at all.
    However, that name describes its construction rather nicely.
    Jim Bennett wrote "Dividing the Circle", before he became Director of the
    MHS in Oxford, and in that he labelled a sextant with a doubled frame as a
    "pillar-sextant". I don't have that book at hand to consult it now. After
    his appointment, I asked him, some years ago now, about the inconsistency in
    that naming, compared with that of the museum instrument now in his charge.
    He then replied that if he was writing it again, he would describe the
    instrument in his book as a double-frame sextant. That name, also, would
    describe its construction rather nicely; however, that doesn't make it an
    official definition, either.
    I have seen another example of the sextant-on-a-stand in the impressive
    houseful of scientific instruments belonging to a wealthy and experienced
    collector, who has since died. This was on a display shelf, beautifully
    polished, but had remained for years in the folded-up state in which it had
    been packed in its original transit box. Together, we unfolded it, and
    turned the sextant the right way up (for the first time for many years, no
    doubt), when its function became at once apparent. He didn't know what it
    should be named, and until that moment, hadn't even recognised what it was
    I can't recall having seen such an instrument in a textbook, so if anyone
    discovers such a reference, or a picture, I would be pleased to learn about
    it. Perhaps they can be found in museum catalogues, if we can discover the
    name they are listed under (which is the problem we're trying to solve). I
    will consult a helpful expert at Greenwich. For our present purpose it would
    be useful to consult a contemporary Troughton sales catalogue, if such a
    thing exists. I will ask if it does.
    So I return to Frank's comment "I haven't found a single case of this usage
    in the lit." . Does he know of ANY such reference in the literature to such
    an adaptation of the sextant on a stand, under any other name, then? I would
    like to discover more. There is no doubt such instruments existed, as I have
    seen two of them. And we can deduce what they were probably intended for,
    simply by looking hard at them. They could have been more common in that
    nineteenth-century heyday of exploration.
    As an example of the use of the word "pillar-sextant" to describe an
    instrument with two thin frames, with spacers between, I have referred to
    Jim Bennet's book, above, but can't quote, off-hand, any more, other than
    Lecky, below. Most relevant would be references from before 1889, when White
    wrote his paper. Can anyone help?
    I was indeed aware of the use of the term "pillar-sextant", in Lecky's
    "Wrinkles". Lecky was an advocate of the "pillar-sextant", whatever he meant
    by that term, but what he says could be read in two ways. Here are his
    words, taken from my 19th edition of 1917.
    "... A 6 or 7-inch sextant is of course somewhat lighter to handle, but
    sailors are not women; and a certain amount of weight gives steadiness,
    especially in breezy weather. The writer's instrument is a 10-inch "pillar",
    by Troughton, divided on platinum.
    The old recommendation was to give preference to a "pillar"sextant; in its
    day it was without doubt THE correct thing, if only because the make was
    confined to the very best instruments, and therefore a guarantee of good
    workmanship.  But the world moves in, knowledge increases, good things are
    superseded by better, so farewell to the "pillar".
    That left me undecided whether Lecky was boasting about his ability to
    manage a the weight of a 10-inch sextant, which had been originally intended
    for mounting on a pillar rather than held in the hand, or whether he was
    saying that a 10-inch sextant built with two spaced thin frames was
    therefore light enough to be hand-held. Both readings seemed plausible to
    Frank tells us-
    |..        In the period, the term was used for the
    | well-known double-frame design, originally patented by Troughton. For
    | example, in Lecky's sextant buying suggestions, he writes, "Give the
    | preference to a "pillar" sextant over one whose framework is cast all in
    | piece" (Lecky's Wrinkles in Practical Navigation, 1884, via Google Books).
    Well from those words of Lecky's in that earlier edition, his meaning of the
    term becomes quite clear. And if that design was patented by Troughton,
    under the name "pillar sextant", then White's meaning is also clear, and my
    interpretation of his words was wrong.
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    To post to this group, send email to NavList@fer3.com
    To unsubscribe, send email to NavList-unsubscribe@fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site