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    Re: Determining refraction in 19th Century
    From: Bruce J. Pennino
    Date: 2018 Jun 21, 09:12 -0400
    Hello:
     
    I  tried to wade through this book. Read most of it. It is a great source of very detailed  information and gives extensive references.  All good, but  WOW a LOT  of detail. For their land control points they were striving for fractions of a second of arc....little did they know that everything is moving!!!  I don’t know how modern surveyors doing extremely fine  geodesic work account for X, Y, and Z movement of land control points. Somebody must be adjusting some giant global system of control points?  Control points from stars?? But don’t stars move too? Expanding universe? Beyond me.
     
    Have a good day.
    Bruce
       
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