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    Re: Dava Sobel
    From: George Huxtable
    Date: 2006 Apr 30, 20:46 +0100

    Frank Reed wrote-
    
    |...And  it's worth remembering that Tobias Mayer offered a
    | complete solution for the  longitude problem including a reflecting circle. He
    | was after the prize. The  3000 pound reward delivered to his widow after
    | Mayer's untimely death was  something like ten times the astronomer royal's annual
    | salary. Big  money.
    
    Yes and no.
    
    Mayer's work as an astronomer on the Moon predictions was intended for its own 
    sake, and to help geographers and mapmakers. No doubt
    he was aware of the British longitude prize, which had been on offer for 30 
    years or so, but was only persuaded to apply for it by
    Euler, in a letter, on record, in mid-1754. To do so, Mayer needed a suitable 
    instrument, to measure lunar distances more precisely
    than could the Hadley octant of the day. He had already developed the 
    "repeating principle", which allowed multiple measurements of
    an angle to be copied and automatically summed, around a circular scale, as a 
    surveying device. This allowed the greatest errors,
    those of unequal division of the scale, to be averaged out. He quickly adapted 
    that design into a double-reflection instrument, to
    make it suitable for use at sea. He sent a wooden model of that circle to 
    London, with a description, and a copy of his tables, in
    Winter 1754.
    
    So, it's only those final stages that were driven by motivation for the prize, 
    according to Eric Forbes, "Tobias Mayer (1723-62),
    Pioneer of Enlightened Science in Germany", (Gottingen, 1980). In which case, 
    it seems unlikely that the development of a system for
    finding longitude by lunars would have waited much longer, even if there had been no such prize.
    
    George.
    
    contact George Huxtable at george---.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
    

       
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