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    Sea Day versus Astronomical Day
    From: Robert H. van Gent
    Date: 2017 Aug 10, 15:11 +0000



    In today’s posting on another mailing list the claim is made that in maritime circles the “sea day”, rather than the “astronomical day” or the “civil day”, was in common usage until about 1868.


    The citation is from




    but a later example of its use is in the 1874 edition of the _American Practical Navigator_.




    Any later examples known?


    Thanks in advance,


    Rob van Gent


    From: Bart Fried [mailto:oldscope@gmail.com]
    Sent: 10 August 2017 16:49
    To: rete@maillist.ox.ac.uk
    Subject: RE: [rete] Transit of Venus 1761


    ---------- Forwarded message ----------
    From: Roger W. Sinnott <roger.sinnott@verizon.net>
    Date: Thu, Aug 10, 2017 at 9:25 AM
    Subject: RE: RE: [rete] Transit of Venus 1761
    To: Bart Fried <oldscope@gmail.com>



    Thanks for forwarding this discussion.  In addition to the “astronomical day” (beginning at noon of the civil date), there was the “sea day” (beginning at noon of the preceding civil date).


    The astronomical day was in general use by astronomers before 1925.  The “sea day” was in use aboard ship up to about 1868, I think.  I have a navigation book published then, which said: “We think it would be advisable to dispense altogether with this absurd sea day, and adopt the astronomical day. Cannot a move be made in this direction?  A good many errors would be avoided by so doing.”





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