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    Re: Home made artificial horizon
    From: Gary LaPook
    Date: 2011 Oct 5, 13:31 -0700
    Hmmm.... if you kept your bottle of mercury under your parka and then poured it into the tray, it would level itself and then freeze in that position (like my wax horizon) and you wouldn't need to place a mirror on top of it (like with the wax version) to take star sights and you wouldn't have to worry about breezes rippling the surface after it is frozen. Still looks good to me.

    gl


    --- On Wed, 10/5/11, Wolfgang Hasper <wolfgang.hasper@web.de> wrote:

    From: Wolfgang Hasper <wolfgang.hasper@web.de>
    Subject: [NavList] Re: Home made artificial horizon
    To: NavList@fer3.com
    Date: Wednesday, October 5, 2011, 12:28 PM

    Gary,
    mind that mercury will freeze at -38°C and you will
    likely encounter lower temperatures on your way to the
    pole. A strong argument for mirror type horizons.
    ;o)

    http://en.wikipedia.org/wiki/File:Pole-observation.jpg
    Nansen carried one on his sledge attempt for the pole,
    too.

    Wolfgang


    Am Mittwoch, 5. Oktober 2011 00:38 schrieb Gary LaPook:
    > But many real navigators on sledges and elsewhere
    > did carry liquid (including mercury) AHs.
    >
    > gl
    >
    > --- On Tue, 10/4/11, Geoffrey Kolbe
    > <geoffreykolbe@compuserve.com> wrote:
    >
    > From: Geoffrey Kolbe <geoffreykolbe@compuserve.com>
    > Subject: [NavList] Re: Home made artificial horizon
    > To: NavList@fer3.com
    > Date: Tuesday, October 4, 2011, 10:37 AM
    >
    >
    >
    > Robert wrote:
    >
    >
    > I can't take it
    > anymore!
    >
    >  
    >
    > Seems like you folks are going to a great deal of
    > hassle and looking in every hidden corner for the
    > perfect levelling mechanism and/or to make an
    > effective artificial horizon. Short of using a pan
    > of motor oil or getting hold of some mercury, the
    > best option is, in my opinion, to just go out and
    > purchase a Freiberger artificial horizon which comes
    > with all you need to obtain pinpoint accuracy (as
    > much as is possible with a sextant).
    >
    >
    > No no, you don't understand Robert. There is a
    > satisfaction in the process of spending a great deal
    > of time and effort to build an AH as cheaply as
    > possible using plastic, string and sealing wax. ;-)
    >
    >
    > But on the matter of practicality, I have no doubt
    > that you are correct. Could you take the plastic
    > string and sealing wax AH to navigate your sledge to
    > the middle of the Antarctic? Or your camel to the
    > middle of the Sahara desert? Possibly, but people
    > have certainly been there and done that with a
    > Freiberger AH. I took the short cut many years ago
    > and bought one.
    >
    >
    > One note on the use of levels. Just because the
    > graduation on the level is only one mil say, (about
    > 3 MOA), does not mean that you are limited to an
    > accuracy of 1 mil in level adjustment. By turning
    > the level end for end for comparison and estimating
    > the bubble position to one tenth of a graduation, it
    > is possible to get an accuracy in level-ness at
    > least an order of magnitude better than the level
    > graduations would suggest.
    >
    >
    > Geoffrey Kolbe



       
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