Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Name or NavList Code:
    Re: Mirror horizon
    From: Paul Saffo
    Date: 2023 Sep 6, 16:21 -0700

    I heartily agree, art! I cycled through all sorts of AH lash-ups... front surface mirrors, bowls with everything from floating mirrors, automotive oil, to molasses and Karo corn syrup! Oh, and one of the cute plastic Davis AHs.

    Molasses is a great option, but a hassle if spilled. I got the best result (defined as convenience plus reasonable accuracy) by attaching a surface mirror to a plate attached to a surveying tribrach,which I had screwed into a steel plate instead of a tripod so I could set it on a low table).  I even managed to snag several antique K&E black mirror expedition AHs.  In the end I found that, excepting the puddle of molasses,  the stumbling block was getting a reliable level. That and working the leveling screws - nothing except the tribrach leveled out satisfactorily. (Btw, am happy to send pics fo the tribrach setup if anyone is interested)

    I also worked my way through several varieties of bubble horizons.  At one point, I had every variation of Plath's bubble horizons, including the legendary firefly.  In the end I donated all of the AH's to our Rumsey Map Center at Harvard along with all but one of my sextants.  I kept my Horizon Ultra (purchased from the legendary Ridge White) and my favorite AH, the Cassens & Plath "Artificial Bubble Horizon."

    Oh, another fun one was a Wild Astrolabe attachment which I used on both a Wild T1a and Wild T2 theodolite.  Substituting motor oil for the mercury it was supposed to be used with it.  The stability of a thodolite on a tripod made a huge difference, but in the end, I simply took a noon curve with the theodolite using a Roelofs Solar prism. That works exceptionally well, of course.

    My conclusion?  Molasses is reliable, tribrach-and-mirror is less messy, but... nothing beats an ocean horizon!  ;-)

    Browse Files

    Drop Files


    What is NavList?

    Get a NavList ID Code

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.

    Email Settings

    NavList ID Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site