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    Re: Liquid-damped compasses. was: [NAV-L] Refilling a compass
    From: Joel Jacobs
    Date: 2004 Jun 24, 06:17 -0400

    Let me add a bit to what George has proffered without  a lot of citations.
    
    There is much evidence that the Chinese invented the compass maybe 900 years
    ago, and some evidence that there device was a box filled with water, with
    the needle floating on it. The compass points were marked on the rim of the
    box. This invention is attributed to Zeng he.
    
    Here is one reference: http://www.oceansonline.com/zheng.htm
    
    Also, in my experience, which is not as long as Henry's, but still dated,
    compass bowls were filled with a solution of glycerin or a solution of H2O
    and alcohol.
    
    Joel Jacobs
    
    
    ----- Original Message -----
    From: "George Huxtable" 
    To: 
    Sent: Wednesday, June 23, 2004 6:29 PM
    Subject: Liquid-damped compasses. was: [NAV-L] Refilling a compass
    
    
    > Bob Peterson wrote-
    >
    > >Ritchie was the first to develop the "wet-card" compass; previous to
    > >that all compasses were "dry-card" compass of the British type.
    >
    > Permit me to quibble a bit, about that.
    >
    > It's true that the US Navy adopted the Ritchie liquid compass as its
    > standard pattern as early as 1863, while the British Admiralty were to
    > retain the dry-card pattern as their standard for another 40 years.
    >
    > However, Ritchie was in no way the first to develop the liquid compass.
    His
    > design was very similar to one patented by Crow in Britain in 1813. From
    > 1845, the Admiralty had found it necessary to supply liquid
    > steering-compasses to certain ships for use in rough weather, in addition
    > to the standard pattern compass. In that same year trials had shown that
    > dry-card compasses were useless in ship's boats, and soon liquid compasses
    > became standard issue for that purpose.
    >
    > A trial in 1847 compared six compasses, from different makers, on board a
    > steam mail packet. Three of those compasses were liquid-damped, and showed
    > their superiority, but that evidence was insufficient to shift the
    > Admiralty from their dry standard-pattern compass. But the fact that three
    > British makers had liquid compasses available, to supply and test, back in
    > 1847, shows that Ritchie was developing on existing technology, rather
    than
    > innovating.
    >
    > Ritchie had tried to interest the Admiralty in his design for the US Navy,
    > but true to form, the Admiralty did not respond.
    >
    > My information comes from "Steady as she goes", a history of the Compass
    > Department of the Admiralty, by A E Fanning (HMSO, 1986).
    >
    > George.
    >
    >
    > ================================================================
    > contact George Huxtable by email at george@huxtable.u-net.com, by phone at
    > 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    > Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    > ================================================================
    
    
    

       
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