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In 1986 when Will Steger, noted Minnesota adventurer and his partner Paul
Schurke travelled to the north pole, they used a C.Plath Sextant with a
bubble attachment for fixing their position along the way. Keep in mind this
was prior to the arrival of the evil temptress GPS.

Schurke, the navigator on the expedition devised, among other items, a means
by which he could mount his sextant on the dogsled to steady it whilst he
took his observations. Anyone who has used a bubble attachment will
understand the rock steady nerves one must have to keep the bubble from
skittering all over the place. If my memory serves me right, Schurke rigged
up a system whereby the sextant was mounted to a swivel ball head monopod,
by it's handle; the whole works being securely attached to the sled. The
handle was affixed to the monopod by way of the screw cap on the handle; the
latter which had been modified to accomodate the screw post on the monopod.

This type of system would be easy for anyone to rig up, provided they have a
sextant of the type that carries its batteries in the handle (such as a
C.Plath or Cassens and Plath -- I don't know about other brands). All one
has to do it get a machinist to fabricate a replacement screw cap with a
threaded insert on the cap which would then screw into a camera tripod. Now
you have your sextant stand. Granted, this system may not be ideal for
lunars, which sometimes require the lunarian to adopt some rather contorted
poses to take his sights.

I've tried this for ordinary observations and it works rather well although
I have to confess that it is not my preferred technique. If I want
centimetric precision, I'll use my GPS.

Robert


----- Original Message -----
From: "Jim Thompson" 
To: 
Sent: Saturday, April 24, 2004 8:02 PM
Subject: Re: Sextant stands; was Lunar Distances: Graphic Methods


> The same thought struck me today -- I ran across mention of those devices
> for the first time while doing some google research on sextant mirror
> construction.  I had never known about them before.  I then researched
> sextant stands, but found only historical references, so it appears that
> perhaps nobody is marketing them any longer:
>
> http://45.1911encyclopedia.org/S/SE/SEXTANT.htm
> http://www.westsea.com/tsg3/octlocker/octcapchart13.html
> http://www.nla.gov.au/ntwkpubs/gw/47/p22a01.html
> http://www.mat.uc.pt/~helios/Mestre/Novemb00/H61if_2.htm
>
> Jim Thompson
> jim2@jimthompson.net
> www.jimthompson.net
> Outgoing mail scanned by Norton Antivirus
> -----------------------------------------
>
> > -----Original Message-----
> > From: Henry C. Halboth
> > I might note, in this regard, that there does not seem to have been any
> > recent mention of the use of a sextant stand in taking shoreside
> > artificial horizon altitudes, as was done by the hydrographical
surveyors
> > in establishing positions - the sextant stand is pretty well covered in
> > "Hydrographical Surveying", by Wharton & Field, 1920 Edition, and might
> > be of interest to those using the artificial horizon. This is pretty
much
> > the standard work, and might be useful to those seeking more theoretical
> > accuracy than sometimes sought in practical navigation...
>
>

   

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