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    Re: A "three dimensional slide-rule" for celestial
    From: UNK
    Date: 2016 Feb 2, 22:14 -0800

    I am truly impressed by this marvel of German engineering. The secret of the inner workings lies in the fact that the scales, vertical curves and the so-called meridian swing arm all engage with one another in an appurtenant way and move in unison.

    The only concern that I would have is that the five necessary inputs are quite hard to provide with the required precision even if the operator is highly skilled. I would therefore modify the machine in a way that it takes only two inputs: The ships latitude and longitude. That way the position could be obtained more reliably directly from the micrometer drums and it could probably be done in much under two minutes, unless Deutsche Gruendlichkeit prevents it.

    Particularly innovative was the idea to take the hour angle of the sun from a nautical chart. My understanding is that a companion instrument had been designed specifically for the purpose. It consisted of a Zeiss projector mounted directly over the chart table so it could cast a nearly perfect image of the sun onto the chart. The position of the disk was then read independently by three officers with achromatic magnifying glasses, likewise provided by Zeiss. Unfortunately, this second apparatus fell overboard on the first and only sea trial.

    I hope this bit of additional information helps to understand the mechanism.

    Herbert Prinz

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