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    Re: Sextants and Glue [was Sisteco Prismatic Compass]
    From: Fred Hebard
    Date: 2004 Mar 24, 13:31 -0500

    Doug,
    
    Thanks.
    
    The Husun was calibrated in 1948.  It has the small mirrors and the
    telescope screws into a collar.  The optics are excellent, except the
    horizon mirror needs to be resilvered.  The telescope is better than
    the C+P's 4x star scope, faster and a wider field of view, although
    only 2.5x.  The wide field of view is helped because the telescope is
    closer to the horizon mirror than the C+P's.  However, the smaller
    mirrors may make the entire optical system have a lower aperture than
    the C+P, especially the index mirror.  The collar does not have the
    alignment ring of the older ones, which would be nice to have.
    
    When I bought it, I got it cheap because the handle had "blown-up" from
    a leaking battery.  I had to remove the index arm to repair the handle,
    and I messed up while learning how to do that, apparently moving the
    pivot bearing a bit.  I don't think the sextant had ever been used in
    real life, and had been stored away after the battery leak.  It was in
    pristine condition other than some tarnish, although the box had
    cracked perhaps stored in an attic, and the leaking battery contents
    got on some of the green felt.  I did manage to chip two flakes of the
    black crinkle paint off while learning how to remove the index arm,
    which was too bad.  But I would say overall it's in excellent
    condition, except the handle.
    
    Fred
    
    On Mar 24, 2004, at 12:51 PM, Royer, Doug wrote:
    
    > Outstanding news on your C+P Fred.I also was looking at the moon's
    > cresant
    > and Venus for some time last evening.Beautiful wasn't it.Simply
    > stunning at
    > least from where I was.
    > Is the horizon mirror(and index mirror for that matter)on your Huson
    > the old
    > style small mirrors?I'm not familiar with these old British sextants
    > and am
    > just curious.What year was it manufactured?Is it a vernier or tangent
    > screw
    > type?How "good" are the optics compared with others?Does it have the
    > collar
    > that the tube screws into(as in the old David White Mk.IIIs)or does the
    > optic assembly fit into a screw on the frame?
    > Just curious.
    >
    > -----Original Message-----
    > From: Navigation Mailing List
    > [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Fred Hebard
    > Sent: Tuesday, March 23, 2004 20:03
    > To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    > Subject: Re: Sextants and Glue [was Sisteco Prismatic Compass]
    >
    >
    > Well, the old C+P I got might be an OK instrument!  I took two sights
    > tonight, of Jupiter & Sirius and Ho-Hc for three replications of each
    > was 0.042896+/-0.308899, and -0.07455+/-0.212369, where the error
    > figure is the square root of the mean of (Ho-Hc) squared; since Hc is a
    > parametric mean, the degrees of freedom should equal the number of
    > replications.  I've never gotten so close previously, although the
    > standard deviations leave a bit to be desired.  Ten to thirty more
    > shots and I might get a fair idea of how good this sextant is.
    >
    > I was driving west and north for a few hundred miles this evening and
    > the new moon was hanging about 15-20 degrees underneath Venus.  It was
    > perfectly clear and still and would have been a beautiful lunar, easy
    > to shoot.   Of course when I got home, the low western sky had clouded
    > over.
    >
    > I have a fair amount of data for my Husun now, which I may get a chance
    > to share with the list.  It appears to need about 25 seconds of arc
    > added to the existing corrections, although there's some additional
    > periodicity in the errors which I don't know how to handle, having
    > never fit such data.  I still need to get a chance to fool around a bit
    > with the data first.  It would help also if I broke down and got the
    > Husun's horizon mirror resilvered.
    >
    
    
    

       
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