Time is important. Keeping accurate time has been one of the major challenges of technology throughout all of history. Here’s a little history lesson from the US Navy:
In 1845, at the request of the Secretary of the Navy, the Observatory installed a time ball atop the 9.6-inch telescope dome. The time ball was dropped every day precisely at Noon, enabling the inhabitants of Washington to set their timepieces. Ships in the Potomac River could also set their clocks before putting to sea. The Observatory’s Time Service was initiated in 1865. A time signal was transmitted via telegraph lines to the Navy Department, and also activated the Washington fire bells at 0700, 1200, and 1800.
Daylight Savings and Olson Files
It turns out, there is a group of files that keep a record of all the daylight savings rules across the world just for this kind of thing:
The tz database, also called the zoneinfo database or IANA Time Zone Database, is a collaborative compilation of information about the world’s time zones, primarily intended for use with computer programs and operating systems. It is sometimes referred to as the Olson database after the founding contributor Arthur David Olson.