when did China adopt one time zone?

[Paul Eggert]

In a book review in today's issue of _Science_ you reported that the
Chinese government in 1949 opted to observe one time zone.  This
caught my interest because I help maintain the tz database, which
records histories of time zone and daylight saving changes all over
the world.  The tz database is used by computer clocks all over the
world, including what I expect are millions of clocks in China, so I'd
like to get the details right.

Here's the problem: the tz database, following Shanks & Pottenger
(2003), records that the China switched to a single time zone on May
1, 1980, not in 1949.  Since you are a historian of China I expect
that you have a lot better sources than we do.  Can you please mention
the sources for the claim that the clocks changed in 1949 rather than
in 1980?

Thanks for any info you can provide.  I'll CC: this message to the tz
database mailing list, to give them a heads-up on this query.

-- Paul Eggert, UCLA Computer Science Dept.

References:

Thomas S. Mullaney, Change of time over changing time.  Science 319
(5864), 729 (2008-02-08), DOI: 10.1126/science.1152851,
<http://www.sciencemag.org/cgi/content/full/319/5864/729a>.

Paul Eggert & Arthur David Olson, Sources for time zone and daylight
saving time data <http://www.twinsun.com/tz/tz-link.htm> (2007-12-31);
also see <http://en.wikipedia.org/wiki/Zoneinfo>.

Thomas G. Shanks and Rique Pottenger, The International Atlas (6th
edition).  San Diego: ACS Publications, Inc. (2003).