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  1. #51
    Join Date
    Aug 2006
    Location
    Burnham-on-Crouch, UK
    Posts
    592

    Default Re: A Lesson in Physical Chemistry

    Quote Originally Posted by Black Diamond View Post
    Good to see that the nondescript shed on Newlyn Pierhead has gained Grade 11 Listed Building status, presumably for services to chart datum?
    As I understand it, the relationship between Newlyn and chart datum is complex and fairly remote. Chart depths are usually plotted relative to local Lowest Astronomic Tide. Newlyn came to fame by providing the datum for the Ordnance Survey. As I recall, , the datum was defined as Mean Low Water Ordinzry Spring Tide at Newlyn. Apologies to the late John Le Mare, my Geography teacher in 1961, if I got that wrong.

    Peter.

  2. #52
    Join Date
    Mar 2014
    Posts
    59

    Default Re: A Lesson in Physical Chemistry

    Quote Originally Posted by PeterWright View Post
    As I understand it, the relationship between Newlyn and chart datum is complex and fairly remote. Chart depths are usually plotted relative to local Lowest Astronomic Tide. Newlyn came to fame by providing the datum for the Ordnance Survey. As I recall, , the datum was defined as Mean Low Water Ordinzry Spring Tide at Newlyn. Apologies to the late John Le Mare, my Geography teacher in 1961, if I got that wrong.

    Peter.
    Mean sea level I think. Used to be Liverpool Dock. Old Victorian London surveys show Liverpool as the datum which I've always found surprising. Not really relevant to floaty things unconnected with land.

  3. #53
    Join Date
    Apr 2013
    Posts
    6,922

    Default Re: A Lesson in Physical Chemistry

    A brief review of UK tidal measurement pre-Newlyn in the introduction to this paper – Sheerness had the first automatic gauge. http://nora.nerc.ac.uk/id/eprint/512...%20England.pdf

    More on Liverpool here: http://www.tide-and-time.uk/tidal-science-liverpool

  4. #54
    Join Date
    Aug 2006
    Location
    Burnham-on-Crouch, UK
    Posts
    592

    Default Re: A Lesson in Physical Chemistry

    Quote Originally Posted by Chalk View Post
    Mean sea level I think. Used to be Liverpool Dock. Old Victorian London surveys show Liverpool as the datum which I've always found surprising. Not really relevant to floaty things unconnected with land.
    Ah, quite right. Mean sea level for the OS and MLWOST was LAT's predecessor as chart datum. Liverpool did precede Newlyn for the OS datum, but that was before Mr Le Mare's time, let alone mine. I was interested to read that tide gauges at Liverpool, Newlyn and our own Felixstowe were considered for Ordnance datum. The Newlyn gauge won as the most directly attached to the wofld by solid rock - seems fair enough.

    Peter.

  5. #55
    Join Date
    Apr 2013
    Posts
    6,922

    Default Re: A Lesson in Physical Chemistry

    Quote Originally Posted by PeterWright View Post
    ... The Newlyn gauge won as the most directly attached to the wofld by solid rock - seems fair enough. ...
    That, and because it was nearer the edge of the continental shelf and more representative of the deep ocean, rather than the shallow waters of the North /Irish Seas, so having fewer large storm surges – and was better maintained, by a scientific organisation.

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