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    Re: Cleaning arc of Vernier sextant.
    From: Robert Eno
    Date: 2006 Oct 28, 11:37 -0400

    I have been silently following this thread for the last few days. One wag
    alluded (in a jovial manner, I am quick to add) to our friend George being
    somewhat of a Luddite and/or overly-thrifty by congratulating him on taking
    the plunge into the world of quality metal sextants.
    
    If such is the case, I have to ask George the obvious question:
    
    George, once you decided to acquire a metal sextant, why didn't you just go
    the whole way and purchase a micrometer drum sextant? Then you would not
    have to concern yourself with stockpiling other people's cigar ashes or
    going through the painful tedium of trying to read a vernier scale under
    poor light conditions.
    
    I look forward to someday reading about George's acquisition of a proper
    micrometer drum sextant. The saga continues.....
    
    
    Robert
    
    
    
    ----- Original Message -----
    From: "Henry C. Halboth" 
    To: 
    Sent: Friday, October 27, 2006 11:45 PM
    Subject: [NavList 1494] Re: Cleaning arc of Vernier sextant.
    
    
    >
    > To all,
    >
    > Frank has asked how the sextant arc and vernier was polished with ashes.
    > I know of no technical dissertation on the subject, but can state my
    > experiences with the caveat that there well may be other ways - under the
    > general heading "different ships, different long splices".
    >
    > Being a smoker in those days, I kept a little tin of cigarette/cIgar
    > ashes. or fag-ash as George has so wonderfully said, carefully sorted
    > through to insure no unburned or other contaminating residue - actually
    > my recollection is that cigar ash formed the best and finest abrasive. To
    > use, one simply touched a finger draped bit of fine cloth to the ash and
    > ran it lightly over the arc until the desired luster was obtained. In the
    > shipboard environment, the cloth was probably sufficiently damp for the
    > ash to adhere, whereas, in a low humidity environment it would probably
    > be appropriate to dampen the cloth a bit. This method of polishing a
    > sextant arc is certainly not a figment of my imagination, although I
    > cannot with certainty say whether I read it in some obscure publication
    > of yesteryear or if it was passed to me by word of mouth.
    >
    > George has mentioned the difficulty in obtaining sufficient lighting to
    > read-off the vernier of a sextant. There is no question but that accuracy
    > in reading-off is significantly affected by the lighting employed. Not so
    > much the actual light or its intensity, but rather the angle at which it
    > strikes the vernier/arc interface. The light source, whether it be the
    > sun or lamp, should be so positioned that the maximum intensity is
    > directed along the index arm at right angles to the vernier/arc
    > interface. In the daytime, this does not present much of a problem; all
    > one need do is step out of the chart house and direct the sunlight
    > appropriately - as a matter of fact, the frosted glass panel usually
    > affixed to the index arm, just above the vernier, is for the purpose of
    > diffusing that sunlight to dampen excessive reflection from the arc while
    > reading through the magnifier. At night, or at twilight in taking star
    > sights, one must of course use the chart table light or some other
    > convenient source; again the light must be directed along the index arm
    > and the sextant manipulated so as to obtain the maximum intensity at the
    > interface. After a time, it all becomes second nature and no great
    > problem. It may well be that at least some of the reticence to star
    > sights or other night observation originated in lighting difficulties
    > mentioned by George.
    >
    > Regards,
    >
    > Henry
    >
    > On Thu, 26 Oct 2006 23:02:00 EDT FrankReedCT@aol.com writes:
    >> Henry H you wrote:
    >> "If the truth were to be known, the conventional wisdom of my day
    >> was  to
    >> leave the sextant alone, crud and all. The more encrusted a
    >> sailor's
    >> sextant might be, the more experienced he (no shes then) and
    >> competent he
    >> was thought to be. The cigarette/cigar ash polish was advanced  as
    >> an
    >> alternative for the fastidious to use. How times have changed!"
    >>
    >> Can you  describe this process of polishing with ashes? I'm having a
    >> hard
    >> time picturing  it. Are you pouring ashes onto the arc and then
    >> rubbing them with
    >> your finger,  or do you rub the cigarette/cigar itself, ashen end
    >> down, along
    >> the  arc?
    >>
    >> -FER
    >> 42.0N  87.7W, or 41.4N  72.1W.
    >> www.HistoricalAtlas.com/lunars
    >>
    >>
    >>
    >
    > >
    
    
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