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    Re: International Date Line --invented by Schedler
    From: John Huth
    Date: 2011 Jul 7, 11:21 -0400
    Frank - 

    I still think it needs a definition of 'real world' here.   There's also a human world which requires some standardization for commerce.

    The period around the 1880's saw a standardization of a Prime Meridian, the establishment of time zones and the international date-line.

    If we flip back to, say, 1750, time was kept by sundials, and, given the travel times, the difference of four minutes for midday between two distant cities was inconsequential.   Once you start to have trains on the same track and you don't want them to collide, there's some need to standardize time conventions.   

    If you try to roughly place the meridian passage of the Sun at local 12:00, give or take, but still have some global synchronization, you're led to the concept of time zones.   If you then call the Greenwich meridian UTC=0, then you're left with the anti-meridian and its meaning in terms of this scheme.   

    Obviously you have to define the point where the date switches, and then you're left with the politics of how to snake from the anti-meridian to the International Date Line. 

    So, I would say it reflects a human and political reality that has its basis in global synchronization, in trying to get local clocks to have 12:00 coincide roughly the the Sun's meridian passage, and yet create a standard.

    If you defined Cambridge, MA as the Prime Meridian, you'd end up with a different international date line, which would probably be much more difficult to draw.   

    As it stands, from a geographic standpoint, the choice of the Greenwich Meridian as the PM puts the anti-meridian in a relatively underpopulated part of the globe, so it's a somewhat natural choice, given geography and the desire to have timezones.

    Yes, it's political and based on human needs, but I don't think that is necessarily 'not real'.

    John H. 

    On Thu, Jul 7, 2011 at 7:03 AM, Frank Reed <FrankReed@historicalatlas.com> wrote:

    I've said before that the so-called "International Date Line" is a map-makers' fiction or invention. So after some research, I think we can pin this on one specific map-maker and publisher of globes, namely Joseph Schedler, of New York, in the late 19th century, circa 1880, who may actually have invented the expression "International Date Line" itself, and who may have started the obsession with drawing a line which has no basis in the real world.


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