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    Re: Lightning at sea - James Cook - Chain
    From: Trevor Kenchington
    Date: 2004 Oct 16, 20:24 +0000

    Before anyone draws any comfort at all from 18th-century experiments
    with lightning chains, it might help to think a bit further about the
    meaning of "chain".
    
    Say the word to most members of this list and I'd guess that the mental
    image created is one of an anchor chain or at least a chain with oval
    links like that used for an anchor cable. (Say "chain" to a cyclist and
    you will create a quite different image in his mind.) So it is worth
    remembering that Cook most likely never saw, or even heard of, an anchor
    chain. They did not become standard issue in the RN until around 1811
    and would not have been economically viable in Cook's time. "Chain" to
    Cook, without other context, would probably have meant the rigging
    chains which linked his ship's deadeyes to her topsides. Those were
    shaped as oval links (not the flat straps used in the later 19th
    century) but far more elongated than the links of any anchor chain.
    
    However, Cook and the navy in which he served were also very familiar
    with chain pumps (which had been introduced by 1600), the "chain" of
    which had far more complex and specialized segments than those of a
    modern drive chain, let alone those of an anchor chain. A service with
    that experience which was experimenting with lightning chains would not
    have been confined to oval links. Given modern knowledge, it could have
    tried a "chain" made of a series of pieces of iron strap, linked at
    their ends in the manner of door hinges -- not as effective as an
    installed continuous copper conductor but able to be stowed below when
    not in use, protected from corrosion and certainly a far better
    conductor than any anchor chain.
    
    Unfortunately, none of my reference texts on 18th-century ship fittings
    even mention lightning chains, far less do they illustrate any examples,
    so I cannot confirm what designs were used.
    
    
    Trevor Kenchington
    
    
    --
    Trevor J. Kenchington PhD                         Gadus{at}iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
    
                         Science Serving the Fisheries
                          http://home.istar.ca/~gadus
    
    
    

       
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