[LEAPSECS] Bulletin C and all that

Kevin Birth Kevin.Birth at qc.cuny.edu
Mon Jan 26 11:41:02 EST 2015

To give historical substance to what Gerard Ashton just wrote, when the
Gregorian calendar was implemented, there were multiple ways of defining
the start of a new day.  Attached is an image of a guild masterpiece clock
from Augsburg made in 1652 for the female wing of the Wittelsbach court of
Bavaria (this clock is in the Frick Collection).  On the dial are the
following times:

The black roman numerals are small clock hours--this is what we use today.
The next ring in (in gold) are Italian clock hours.  These are numbered 1
to 24 beginning at twilight. These were associated with some Italian
city-states and went out of use in the 19th century and were officially
discontinued in 1878.
The next ring in (half silver/half black) are Nuremberg or Great clock
hours.  These involve different counts for daylight and nighttime hours.
For instance, on the summer solstice, the daytime hours run from 1 to 17
and the nighttime hours from 1 to 7. These were officially discontinued in
This clock does not include astronomical clock hours (1 to 24 beginning at
solar noon), or southern European clock hours (1 to 24 beginning at
sunrise), or canonical hours (variable depending on the time of year) or
what is now called military time (1 to 24 beginning at midnight).

As an aside, because 6 o'clock in small clock hours lines up with 24
o'clock in Italian clock hours and the division between day and night in
Nuremberg clock hours, one can ascertain that this photo was taken when
the clock's date was set to an equinox.

The ascendency of the small clock hours is linked to the ascendency of
France and the UK over trade in the 18th century and then the
disappearance of small states that took pride in their own timescales in
the 19th century.  Pan-national standards tend to be driven by economics
associated with trade.  The ISO is no different, and is a product of the
need for standards in the global economy.

Since the global economy is not egalitarian, it is not the case that
everyone has an equal voice.  Sometimes it is the market that shapes the
standards that become common.  Such was the case with small clock
hours--there was a greater demand for clocks and watches with these hours
than with the other alternatives, so the other alternatives gradually
disappeared (a bit like 8-track tapes).  Sometimes standards are shaped by
powerful nations colluding to make a decision for the globe.  This was the
case with the UK-US coalition at the International Meridian Conference of



Kevin K. Birth, Professor
Department of Anthropology
Queens College, City University of New York
65-30 Kissena Boulevard
Flushing, NY 11367
telephone: 718/997-5518

"We may live longer but we may be subject to peculiar contagion and
spiritual torpor or illiteracies of the imagination" --Wilson Harris

"Tempus est mundi instabilis motus, rerumque labentium cursus." --Hrabanus

On 1/26/15 10:44 AM, "G Ashton" <ashtongj at comcast.net> wrote:

>ISO 8601 defines for its purposes midnight as the start of the new day
>end of the old day). But that does mean that since 1582 everyone who uses
>used the Gregorian calendar as their civil calendar has/had also used
>midnight to divide days. Such usages may have exist, they just would not
>ISO 8601 compliant.
>Gerard Ashton
>Brooks Harris wrote in part:
>Sent: Sunday, January 25, 2015 23:29
>To: leapsecs at leapsecond.com
>Subject: Re: [LEAPSECS] Bulletin C and all that
>8601, 3.2.1 The Gregorian calendar, says:
>"This International Standard uses the Gregorian calendar for the
>identification of calendar days."
>Earlier, it says:
>2.2.6 calendar day - "time interval starting at midnight and ending at the
>next midnight, the latter being also the starting instant of the next
>calendar day"
>8601 is more carefully constructed than you give it credit for, and its an
>international standard. "Difficult" yes. "Garbage", certainly not.
>> Gerard Ashton
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