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On 2018-05-20 0:15, I wrote:
>
> In
> a controversial step adjustment, GMT changed to the civil time
> convention at the beginning of 1925.

The idea had been around for decades. A resolution at the 1884
Washington meridian conference expressed "the hope that as soon as may
be practicable the astronomical and nautical days will be arranged
everywhere to begin at mean midnight."

Astronomers generally were opposed. "Two of our highest astronomical
authorities have recently pronounced their verdicts upon the decision of
the Washington Prime Meridian Conference with respect to the
astronomical day, and in each case the verdict is an adverse one." The
astronomers were Foerster and Newcomb.


http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1885Obs.....8...81.&db_key=AST&classic=YES

Asaph Hall (discoverer of the moons of Mars) at the USNO took a poll of
astronomers connected with the observatory. All were against any change.
"I submit that the opinion of the above astroomers on this question is
of greater value than that of the admirals, generals, and diplomats who
so largely formed the Conference that assembled in Washinton in the
autumn of 1884."

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1886Obs.....9..161H&classic=YES

Some astronomers saw the other side of the argument, however. An 1895
report by the French Bureau of Longitude said, "It is obviously
inconvenient for the astronomer to change the date in his observing book
in the midst of a night's observations; it is legitimate to fear that he
might even often forget to do this, and that the errors which might
result would be difficult subsequently to discover and to correct. This
inconvenience, however, has to be faced already under the present system
in the case of observations of the Sun, and, as these are the most
common observations at sea, sailors have constantly now to face the same
inconvenience which appears so terrifying to astronomers.

"The Bureau of Longitudes is in agreement, in principle, with the reform
proposed by the Canadian Institute for the change of the commencement of
the astronomical day."

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1917Obs....40..323.&classic=YES

I believe a 1917 letter by eminent astronomers Dyson and Turner,
published in "The Observatory," was the seed that finally caused the
re-definition of GMT.

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1917Obs....40..301D&classic=YES

This British movement was noticed in America. In 1918, Publications of
the Astronomical Society of the Pacific said, "For several decades a
proposal to have the astronomical day begin at midnight has received
serious consideration. Following the lead of the Royal Astronomical
Society of London, the American Astronomical Society in 1917 appointed a
committee to consider and report upon the proposal... There appear to be
no seriously inconvenient consequences of the proposed change, even in
the debated matter of the Julian day reckoning. It will merely be
necessary to remember that 0.5 day should be added to every Julian date
prior to 1925 when comparing observing times before 1925 with observing
times following January 1, 1925.

"The opinion of practical navigators as to the desirability of the
change appears to be almost unanimous in its favor."

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1918PASP...30..358C&classic=YES

(In the end, a change to the Julian date reckoning didn't occur. Thus
the fractional portion of a JD still rolls over at noon UT.)

Apparently the times were ripe, since the new GMT appeared in the 1925
almanacs. But even after the date of the big change was set, there were
letters wondering if it could be stopped: "What do we gain by this
change except greatly increased risk of error and further confusion to
future investigators? The introduction of the egregious 'Daylight Saving
Time' has already caused such confusion in the time-keeping records all
over the world that on would have thought that it was all the more
essential that the standard system represented by G.M.T. should be
continued. We were told that there was a pressing demand from the seamen
for this change, but rumour says that the sailor-men now say they wanted
no change. Has anyone ever heard of a ship being lost because the
navigator forgot that the astronomical day began at noon?"

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1921Obs....44..123T&classic=YES

Dyson (the Astronomer Royal) took a pragmatic view: "When, a year or two
ago, the use of time commencing at midnight was decided upon for the
Nautical Almanac from 1925 onwards, I was in favour of marking the
change by a use of different symbols, such as G.T., but am now
reconciled to the use of the old form G.M.T. ... The fact must be
admitted that the phrase Greenwich Mean Time to non-astronomical people
means time commencing at midnight. It is no use astronomers protesting
that Greenwich Mean Time commences at noon. They are only considered
pedantic. On this account the best way to secure uniformity in
time-reckoning is frankly to adopt the popular usage from 1925, and to
add the word (Civil) to the letters G.M.T. where there is any chance of
a mistake.

http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1921Obs....44..158D&classic=YES

I have looked in the literature for post-1925 complaints about the new
GMT, but the naysayers seem to have fallen silent. And I have not
noticed any proposals to return to the old way!

   

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