On Sun 2018-11-18T02:58:04+0000 Joseph Myers hath writ:
So the scenario of the ball being dropped at 17:00 GMT daily appears to be wrong - most likely the astronomer in London got a.m. and p.m. mixed up, and
An astronomer before 1925 referring to GMT would have been using the old astronomical convention where the day started at noon, not midnight.
Yes. On Sat 2018-11-17T21:50:11+0000 Michael H Deckers via tz hath writ:
The source quoted gives just an ante quem datetime for the switch. It suggests that the time ball regularly was dropped at 01 h local time, and that local time had been advanced by 00:23:18.14 h at some time on or before the ball was dropped on 1904-10-30. The source also treats the switch to UT + 08 h as a different event, the "final step" in the adoption of UT + 08 h in Hong Kong. On would not expect such a wording if the switch had happened at the same time.
According to the observations made at Hong Kong Observatory by the folks whose clocks controlled the drop of the time ball Meteorological Observations made at the HongKong Observatory in the year 1904 page 4 https://books.google.com/books?id=kgw5AQAAMAAJ&lpg=RA7-PA31&dq=hong%20kong%2... the time ball is not dropped on Sundays or Government holidays, but the log of drop times in Table 2 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. Michael Deckers is probably right that the change was effective in the middle of the night between Saturday and Sunday (but a lot of clocks would not have been reset until observation of the usual and expected time ball drop on Monday). -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m