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    Re: Latitude by Talcott-Horrebow Method
    From: Geoffrey Kolbe
    Date: 2018 Nov 17, 11:20 -0800

    I have just been reading "A Field Evaluation of the Kern DKM3-A Astronomical Theodolite for Precise Astronomic Position Determination" by William Eugene Carter of Ohio State University, 1965.

    The tests were done at an observing station where they had always used the Wild version of a first-order astronomical theodolite, the Wild T4. The Latitude and Longitude of the observing station determined using the Wild T4 over a long period was 

    Latitude 28° 34' 03.60" North

    Longitude 05hr 25m 17.355sec West

    The Kern DKM3-A trial during one night gave:

    Latitude 28° 34' 03.63" +/- 0.04" determined using the Talcott-Horrebrow method.

    Longitude 05hr 25m 17.350sec +/-0.011sec determined using the Meridian-Transit method. (I have no idea who Meridian or Transit were...)

    So, pretty good agreement with the established latitude and longitude and an error circle of radius about 1.5 metres. You could spit out of it!

    Twenty years later, technology had improved to the point where equivalent accuracy could be achieved about 100 times cheaper and 100 times faster. But these old theodolites are certainly objects of beauty!

    Geoffrey Kolbe

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