>From dfb5b6793c1e2cfe6e10376b7eccb377a11933e6 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sun, 18 Nov 2018 00:27:01 -0800 Subject: [PROPOSED] Reinstall the 1904-10-30 Hong Kong change The data entry was right after all, but for the wrong reasons. (Thanks to Phake Nick, Steve Allen, and Joseph Myers.) * NEWS, asia (Asia/Hong_Kong): The 1904-10-30 transition was at 01:00 new time after all. --- NEWS | 4 +++- asia | 31 ++++++++++++++++++++++++++----- 2 files changed, 29 insertions(+), 6 deletions(-) diff --git a/NEWS b/NEWS index 0bea722..9743674 100644 --- a/NEWS +++ b/NEWS @@ -26,7 +26,9 @@ Unreleased, experimental changes Hong Kong observed DST in 1941 starting 06-15 (not 04-01), then on 10-01 changed standard time to +08:30 (not +08). Its transition back to +08 after WWII was on 1945-09-15, not the previous day. - (Thanks to Phake Nick.) Its 1952 fallback was on 11-02 (not 10-25). + Its 1904-10-30 change took effect at 01:00 +08 (not 00:00 LMT). + (Thanks to Phake Nick, Steve Allen, and Joseph Myers.) Also, + its 1952 fallback was on 11-02 (not 10-25). Changes to past tm_isdst flags diff --git a/asia b/asia index 54df1a2..9186094 100644 --- a/asia +++ b/asia @@ -592,14 +592,35 @@ Zone Asia/Urumqi 5:50:20 - LMT 1928 # the day that Hong Kong start using GMT+8 should be Oct 30, 1904. # # From Paul Eggert (2018-11-17): -# Hong Kong had a time ball nearthe Marine Police Station, Tsim Sha Tsui. +# Hong Kong had a time ball near the Marine Police Station, Tsim Sha Tsui. # "The ball was raised manually each day and dropped at exactly 1pm # (except on Sundays and Government holidays)." # Dyson AD. From Time Ball to Atomic Clock. Hong Kong Government. 1983. # -# As 1904-10-30 was a Sunday, most likely the time change did not -# propagate to most of Hong Kong until the afternoon of the next day. -# For now, just record the date, not any time of day. +# "From 1904 October 30 the time-ball at Hong Kong has been dropped by order +# of the Governor of the Colony at 17h 0h 0s G.M.T., which is 23m 18s.14 in +# advance of 1h 0m 0s of Hong Kong mean time." +# Hollis HP. Universal Time, Longitudes, and Geodesy. Mon Not R Astron Soc. +# 1905-02-10;65(4):405-6. https://doi.org/10.1093/mnras/65.4.382 +# +# From Joseph Myers (2018-11-18): +# An astronomer before 1925 referring to GMT would have been using the old +# astronomical convention where the day started at noon, not midnight. +# +# From Steve Allen (2018-11-17): +# Meteorological Observations made at the Hongkong Observatory in the year 1904 +# page 4 +# ... the log of drop times in Table II shows that on Sunday 1904-10-30 the +# ball was dropped. So that looks like a special case drop for the sake +# of broadcasting the new local time. +# +# From Phake Nick (2018-11-18): +# According to The Hong Kong Weekly Press, 1904-10-29, p.324, the +# governor of Hong Kong at the time stated that "We are further desired to +# make it known that the change will be effected by firing the gun and by the +# dropping of the Ball at 23min. 18sec. before one." +# From Paul Eggert (2018-11-18): +# See for this; unfortunately Flash is required. # From Phake Nick (2018-10-26): # I went to check microfilm records stored at Hong Kong Public Library.... @@ -708,7 +729,7 @@ Rule HK 1973 only - Dec 30 3:30 1:00 S Rule HK 1979 only - May Sun>=8 3:30 1:00 S Rule HK 1979 only - Oct Sun>=16 3:30 0 - # Zone NAME GMTOFF RULES FORMAT [UNTIL] -Zone Asia/Hong_Kong 7:36:42 - LMT 1904 Oct 30 +Zone Asia/Hong_Kong 7:36:42 - LMT 1904 Oct 30 0:36:42 8:00 - HKT 1941 Jun 15 3:30 8:00 1:00 HKST 1941 Oct 1 4:00 8:30 - HKT 1941 Dec 25 -- 2.17.1