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Hi everyone, my father recently passed away and while I was going
through his things, I found a few sextants.  One that I am looking at
right now is Fairchild Instrument and Camera Corporation model A - 10
A.  I really know nothing at all about these instruments, I googled
the item number and found this group.  I read the previous postings
and found out how you are supposed to use them, so I looked through
the lens and saw the bubble that is supposed to be there (I
guess!?!).  I don't know if this is in working condition, or the best
place for me to sell it, or if it would be best if I donate it to a
museum.  If anyone could help in providing some information it would
be very much appreciated.  I can be contacted at my email which is
bmcwhort@gmu.edu.  Thanks in advance for any help.  Benjamin
McWhorter.

On Jul 14, 6:43 pm, Ken Gebhart  wrote:
> Just a note on filling vapor bubble chambers.  The Tech manuals
> require a vacuum chamber in order to degas the xylene of air before
> introducing it into the chamber.  We found that filling the chamber
> with airy xylene then turning the diaphragm to make a bigger bubble
> works somewhat well.  Doing this 3 or 4 times, and introducing more
> xylene each time will result in a bubble that may be a little hard to
> remove from the field of view when desired, but is acceptable.
>
> Ken Gebhart
> On Jul 11, 2008, at 12:40 AM, engineer wrote:
>
>
>
> > The British Mk IX is about 200 grams lighter. and is  my favourite
> > because all the controls come readily to hand, it is easy to use and
> > read and you have a reasonable chance of getting one that works. With
> > the exception of the averager on the Mk IX A, the works of the Mk IX
> > series are accesible and usually easy to fix. The bubble assembly is
> > also easy to refill.
>
> > My A7 has a vapour pressure bubble chamber which, if empty when you
> > get it is very difficult for the non-specialist to refill. Many of the
> > WW II US instruments suffered from "complification" and some used 4
> > prisms, heavy and expensive to produce. The AN 5854-1's
> > averager(strictly, a median device)is temperamental and hard to fix if
> > it has suffered corrosion in storage. The AN 5851(Navy Mk 5)is heavy
> > and clunky and initial setting of its averager needs care. The A10-A
> > is perhaps the handiest instrument to use, provided the electrical
> > marking system is in good order. It is not impossible for
> > a reasonably handy person to fix the system, once it has been
> > understood. The A10 uses the Mark I finger to operate the marking
> > pencil. That leaves rarer instruments, like the A8-A and the Navy Mk
> > IV. The latter was plainly not a success and if you find one, the
> > averaging system will tax the average person to fix. The A12 is a
> > favourite of many people and was designed to be cheap to produce(some
> > of the others cost almost the price of a small home to produce). The
> > arc and vernier on mine are poorly cut, but if you can get one free
> > from corrosion and in working order it would be a good one to start
> > with.
>
> > The Achilles heel of nearly all the bubble sextants is the bubble
> > chamber. For practical purposes, you cannot refill a vapour pressure
> > chamber. Happily, most of the later bubble sextant produced used a
> > different system with an air reservoir; and these are fairly easy to
> > refill. The MA series are, alas, expensive and do not often come on to
> > the market.
>
> > Bill Morris
>
> > On Jul 11, 1:54 pm, "Gary J. LaPook"  wrote:
> >> My fravorite is my MA-1 which isn't a bubble sextant but a pendulous
> >> mirror type and my second favorite is the MA-2 with a bubble. If you
> >> want a light, simple sextant get a Bendix A-7, it is the lightest
> >> bubble
> >> sextant I have.
>
> >> gl
>
> >> glap...@pacbell.net wrote:
> >>> Here is a link to a site with discriptions of many types of bubble
> >>> sextants:
>
> >>>http://home.earthlink.net/%7Es543t-24dst/airnav/index.html
>
> >>> gl
>
> >>> On Jul 5, 3:19 am, glap...@pacbell.net wrote:
>
> >>>> You should also check the files section of the Yahoo sextant
> >>>> group for
> >>>> more information on sextants.
>
> >>>>http://groups.yahoo.com/group/Sextants/files/
>
> >>>> gl
>
> >>>> On Jul 3, 5:14 pm, bubi352  wrote:
>
> >>>>> I am new to this group and new to celestial navigation. I
> >>>>> currently
> >>>>> work as an airline pilot and fly extensively over water at
> >>>>> night. I
> >>>>> have developed a keen interest in determining my position the old
> >>>>> fashion way.
>
> >>>>> Could someone tell me which bubble sextant I should buy?
> >>>>> What should I be looking on a bubble sextant?
> >>>>> Where can I buy one?
>
> >>>>> Thank you in advance.
>
> >>>>> Bubi- Hide quoted text -
>
> >> - Show quoted text -

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