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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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