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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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