Spring Forward, Fall Back... but why? Take a trip from Railway Time to the Olson database, as we explore the strange history of Time Zones and Daylight Saving Time. This talk was part of EMFCamp 2022.

1. a brief history of
TIME ZONES & DAYLIGHT SAVING TIME
2022-06-03T10:00Z
John Dalziel
|
|
@crashposition
@computusengine
crashposition.com
computus.org

2. AGENDA
Railway Time
Time Zones
Daylight Saving Time
Computers

3. RAILWAY TIME
in BRITAIN

4. RAILWAYS in BRITAIN 1829
Stephenson’s “Rocket”
(1829)
Electric Telegraph
(1840’s)

5. RAILWAYS in BRITAIN 1830
Liverpool to Manchester
Railway

6. RAILWAYS in BRITAIN
Within 25 Years
• The majority of towns
and cities had a rail
connection.
• Over 7000+ miles of
track.
• Top speeds of 78mph
• National regulation,
including Standard
Time based on GMT.
1852

7. RAILWAY TIME in BRITAIN 1840
Journey:
London Paddington to
Bristol Temple Meads
Distance:
118 miles, westward
Travel Time:
~4:00 hours
London
Bristol

8. RAILWAY TIME in BRITAIN 1840
Leave London Paddington
1:00 pm on your pocket watch
1:00 pm in London
Travel for 4 hours
Arrive in Bristol
5:00 pm on your pocket watch
4:49 pm in Bristol
You have travelled for
4 hours, but arrived
11 minutes early.
London
Bristol

9. RAILWAY TIME in BRITAIN 1840
The Sun takes 11 minutes
to pass overhead between
London and Bristol.
Noon in London is
11:49am in Bristol
Noon in Bristol is
12:11pm in London
London
Bristol

10. RAILWAY TIME in BRITAIN 1840

11. RAILWAY TIME in BRITAIN 1840
London
The
fi
rst company to
standardise its timetable was
Great Western Railway in
November 1840.
All trains ran on
Greenwich Mean Time.

12. RAILWAY TIME in BRITAIN 1847
London
GMT became the
Standard Time across
the railway network on
1st December 1847.

13. RAILWAY TIME in BRITAIN 1855
London
By 1855, almost 98% of
British towns and cities
had transferred to GMT.

14. RAILWAY TIME in BRITAIN 1852
The Bristol Exchange clock
• Installed in 1822.
• The red hands show local
time in Bristol.
• The pink hand (added later)
shows GMT.
Bristol o
ffi
cially adopted railway
time on 14th September 1852.
Bristol Exchange Clock

15. RAILWAY TIME
in NORTH AMERICA

16. PROVIDENCE and WORCESTER 1853

17. RAILWAY TIME in USA
In the US each railroad company kept its own time. Usually set to solar
noon at the company headquarters.
- Pennsylvania Railroad: Pennsylvania
- New York Central Railroad; New York Central Station (Vanderbilt time)
- Erie and Luckawana
- Baltimore and Ohio
To travel by rail a passenger must know the time standard used by each
railway. To leave on time, they must convert this to local time in the town of
departure, then do the same to get local time in the town of arrival.
1870’s

18. RAILWAY TIME in USA 1870’s
Pennsylvania Railroad
Philadelphia
New York Central Railroad
New York
Baltimore and Ohio Railroad
Baltimore
Erie Lackawanna Railway
Cleveland

19. RAILWAY TIME in USA 1870’s

20. RAILWAY TIME in USA 1870’s

21. RAILWAY TIME in USA 1883
90° 75°
105°
120°

22. LATITUDE and LONGITUDE
original mage copyright © Free Vector Maps.com

23. LATITUDE
original mage copyright © Free Vector Maps.com

24. THE EQUATOR
original mage copyright © Free Vector Maps.com

25. LONGITUDE
original mage copyright © Free Vector Maps.com

26. THE PRIME MERIDIAN
original mage copyright © Free Vector Maps.com

27. THE INTERNATIONAL DATE LINE
original mage copyright © Free Vector Maps.com

28. TIME ZONES 1883

29. TIME ZONES 1884

30. INTERNATIONAL MERIDIAN CONFERENCE1884

31. INTERNATIONAL MERIDIAN CONFERENCE1884
Austria-Hungary
Brazil
Chile
Colombia
Costa Rica
Italy
Japan
Liberia
Mexico
Netherlands
Ottoman Empire
Paraguay
Russia
Salvador
San Domingo
Canada
United States
Venezuela
Denmark (absent)
France
Germany
Guatemala
Hawaii
Spain
Sweden–Norway
Switzerland
United Kingdom
British India
41 Delegates
from
26 Countries

32. 1. That it is the opinion of this Congress that it is desirable to adopt a single prime meridian for all
nations, in place of the multiplicity of initial meridians which now exist.
2. That the Conference proposes to the Governments here represented the adoption of the meridian
passing through the centre of the transit instrument at the Observatory of Greenwich as the initial
meridian for longitude.
3. That from this meridian longitude shall be counted in two directions up to 180 degrees, east
longitude being plus and west longitude minus.
4. That the Conference proposes the adoption of a universal day for all purposes for which it may
be found convenient, and which shall not interfere with the use of local or standard time where
desirable.
5. That this universal day is to be a mean solar day; is to begin for all the world at the moment of
mean midnight of the initial meridian, coinciding with the beginning of the civil day and date of
that meridian; and is to be counted from zero up to twenty-four hours.
6. That the Conference expresses the hope that as soon as may be practicable the astronomical and
nautical days will be arranged everywhere to begin at midnight.
7. That the Conference expresses the hope that the technical studies designed to regulate and extend
the application of the decimal system to the division of angular space and of time shall be resumed,
so as to permit the extension of this application to all cases in which it presents real advantages.
1884
INTERNATIONAL MERIDIAN CONFERENCE

33. 1. That it is the opinion of this Congress that it is desirable to adopt a single prime meridian for all
nations, in place of the multiplicity of initial meridians which now exist.
2. That the Conference proposes to the Governments here represented the adoption of the meridian
passing through the centre of the transit instrument at the Observatory of Greenwich as the initial
meridian for longitude.
3. That from this meridian longitude shall be counted in two directions up to 180 degrees, east
longitude being plus and west longitude minus.
4. That the Conference proposes the adoption of a universal day for all purposes for which it may
be found convenient, and which shall not interfere with the use of local or standard time where
desirable.
5. That this universal day is to be a mean solar day; is to begin for all the world at the moment of
mean midnight of the initial meridian, coinciding with the beginning of the civil day and date of
that meridian; and is to be counted from zero up to twenty-four hours.
6. That the Conference expresses the hope that as soon as may be practicable the astronomical and
nautical days will be arranged everywhere to begin at midnight.
7. That the Conference expresses the hope that the technical studies designed to regulate and extend
the application of the decimal system to the division of angular space and of time shall be resumed,
so as to permit the extension of this application to all cases in which it presents real advantages.
1884
INTERNATIONAL MERIDIAN CONFERENCE
• 22 Nations voted for Resolution 2. • San Domingo (now Dominican
Republic) voted against.
• Brazil Abstained.
• France Abstained.
• Denmark were absent.

34. 1884
THE WORLD’S MERIDIANS

35. PRIME MERIDIAN 1884

36. The US and British
railway systems already
used Greenwich as a
prime meridian.
Three quarters of the
world's commerce
depended on British
naval charts.
1884
PRIME MERIDIAN

37. PRIME MERIDIAN

38. PRIME MERIDIAN

39. PRIME MERIDIAN 1884
Great Britain (Greenwich)
Spain
France
Algeria
Mali
Burkina Faso
Togo
Ghana
Antartica (Queen Maud Land)

40. PRIME MERIDIAN

41. PRIME MERIDIAN

42. PRIME MERIDIAN

43. The Prime Meridian of
the world is de
fi
ned by the
Airy Meridian at the RGO.
This meridian is de
fi
ned by
the line of longitude of the
Airy Transit Circle
instrument.
1884
PRIME MERIDIAN
George Biddell Airy
(1801 - 1892)

44. PRIME MERIDIAN 1884
MARS

45. MERIDIANS in GREENWICH
Edmond Halley Meridian
John Flamsteed Meridian

46. MERIDIANS in GREENWICH
IERS Reference Meridian
Prime Meridian 102m

47. MERIDIANS in LONDON
Kew Meridian Prime Meridian
Kings Observatory,
Kew
Royal Observatory,
Greenwich

48. MERIDIANS in LONDON
Kew Meridian
Kings Observatory, Kew

49. TIME ZONES in THEORY

50. TIME ZONES in THEORY

51. TIME ZONES in THEORY

52. TIME ZONES in THEORY

53. TIME ZONES in THEORY

54. TIME ZONES in PRACTICE

55. TIME ZONES in PRACTICE

56. TIME ZONES in PRACTICE
Afghanistan
UTC +4:30
Iran
UTC +3:30
India, Sri Lanka
UTC +5:30
Myanmar, Cocos Islands
UTC +6:30
Venezuela
UTC -4:30
Newfoundland
UTC -3:30
Marquesas Islands
UTC -9:30
Central Australia
UTC +9:30
Lord Howe Island
UTC +10:30
Norfolk Island
UTC +11:30

57. TIME ZONES in PRACTICE
Nepal
UTC +5:45
Chatham Islands
UTC +12:45
Eyre Highway
UTC +8:45

58. TIME ZONES in PRACTICE
Line Islands, Kiribati
UTC +14:00
Tonga, Somoa, Tokelau, Phoenix Islands
UTC +13:00
Monday
UTC +12:00
Sunday
UTC -12:00

59. TIME ZONES in PRACTICE
China
UTC +8:00

60. TIME ZONES in PRACTICE
Syowa
UTC +03:00
Mawson
UTC +05:00
Davis
UTC +07:00
Casey
UTC +08:00
Dumont-d’Urville
UTC +10:00
McMurdo
UTC +12:00
Vostok
UTC +06:00
South Pole
UTC +12:00
Palmer
UTC -03:00
Rather
UTC -03:00
ANTARTICA

61. TIME ZONES in PRACTICE
Syowa
UTC +03:00
Mawson
UTC +05:00
Davis
UTC +07:00
Casey
UTC +08:00
Dumont-d’Urville
UTC +10:00
McMurdo
UTC +12:00
Vostok
UTC +06:00
South Pole
UTC +12:00
Palmer
UTC -03:00
Rather
UTC -03:00
0°
UTC +12:00
180°
UTC +12:00
90°
UTC +06:00
270°
UTC -06:00
Prime meridian
International Date Line
ANTARTICA

62. TIME ZONES in PRACTICE
Troll
UTC +00:00 Syowa
UTC +03:00
Mawson
UTC +05:00
Davis
UTC +07:00
Casey
UTC +08:00
Dumont-d’Urville
UTC +10:00
McMurdo
UTC +12:00
Vostok
UTC +06:00
South Pole
UTC +12:00
Palmer
UTC -03:00
Rather
UTC -03:00
0°
UTC +12:00
180°
UTC +12:00
Prime meridian
International Date Line
ANTARTICA

63. TIME ZONES in PRACTICE
“One last quirk about South Pole
time. All the electric clocks are
usually wrong.
Something about the generators
running at 60.1hertz or something
makes all of the clocks run fast.
So every couple of days, we have
to go around and set them back 5
minutes or so.”
- Susan Smith
Troll
UTC +00:00 Syowa
UTC +03:00
Mawson
UTC +05:00
Davis
UTC +07:00
Casey
UTC +08:00
Dumont-d’Urville
UTC +10:00
McMurdo
UTC +12:00
Vostok
UTC +06:00
South Pole
UTC +12:00
Palmer
UTC -03:00
Rather
UTC -03:00
0°
UTC +12:00
180°
UTC +12:00
Prime meridian
International Date Line
ANTARTICA

64. DAYLIGHT SAVING TIME

65. DAYLIGHT

66. DAYLIGHT

67. DAYLIGHT

68. DAYLIGHT
6:00

69. DAYLIGHT SAVING TIME
6:00
Daylight Saving Time

70. DAYLIGHT SAVING TIME
Benjamin Franklin
(1705 - 1790)
1784

71. DAYLIGHT SAVING TIME
Benjamin Franklin
(1705 - 1790)
1784
• A tax of one gold coin per window
with shutters.
• Guards posted in wax and tallow
chandlers, and a maximum of one
pound of candles per week, per family.
• Guards posted to stop all coaches
after sunset (except those of
physicians, surgeons, and midwives).
• Ring church bells at sunrise. If that is
not su
ffi
cient, let cannon be
fi
red in
every street.
BEN FRANKLIN’S PROPOSAL

72. DAYLIGHT SAVING TIME 1895
George Hudson
(1867 - 1946)
• A two hour time shift in the Summer.
George Hudson, a New Zealand Post
O
ffi
ce clerk and amateur entomologist,
made a proposal to the Wellington
Philosophical Society for a two hour
time shift in the summer, to have
more daylight for hunting insects.
GEORGE HUDSON’S PROPOSAL

73. DAYLIGHT SAVING TIME 1907
William Willett
1856 -1915
WILLIAM WILLETT’S PROPOSAL
• Four short Sundays in April.
• Four long Sundays in September.
William Willett, a successful London
builder petitioned parliament for a gradual
clock shift during the summer to avoid
what he called, “The Waste Of Daylight”.

74. DAYLIGHT SAVING TIME 1907
PROPOSED BENEFITS:
• More time to exercise in the open air.
• Increase the usefulness of parks.
• Increased opportunities for ri
fl
e practice
• Reduced cost of lighting (oil, electric,
candles)
• Less coal burning would reduce air pollution.
• Reduced eye strain
WILLIAM WILLETT’S PROPOSAL

75. DAYLIGHT SAVING TIME 1907
FOR:
• 285 members of the House of Commons.
• 59 members of the House of Lords.
• 685 city, town and district councils.
• 59 Trade unions.
• Notable supporters included Herbert Asquith, Winston
Churchill, Sir Arthur Conan Doyle.
AGAINST:
• Nature magazine
• Farmers
WILLIAM WILLETT’S PROPOSAL

76. DAYLIGHT SAVING TIME 1908
Fort William, Ontario 1865

77. DAYLIGHT SAVING TIME 1916
The
fi
rst country to introduce
Daylight Saving Time was
Germany during World War One.
The wished to save coal.
Kaiser Wilhelm II
(1888 - 1918)

78. DAYLIGHT SAVING TIME 1916
Great Britain and the US
introduced Summer Time
soon after.

79. GREAT BRITAIN
During World War Two,
Great Britain was on
Double Summer Time
(i.e. European Summer time)
1941-1944

80. GREAT BRITAIN
2016
RGO Spring Forward exhibition
marks 100 years of British
Summer Time
2016

81. AUSTRALIA
No DST
2022

82. CANADA
No DST
2022

83. USA
No DST
2022

84. USA
No DST
2022

85. USA
No DST
2022

86. USA
• The Sunshine Protection Act passed
the US Senate in March 2022. The bill
has still to pass the House and be signed
into law by the President.
• This act aims to put US on permanent
DST from Nov 2023.
• The US tried permanent DST in 1974 and
rejected it. Popularity for permanent DST
went from 79% in 1973 to 42% in 1974
2022

87. EUROPE
• European Union voted in 2018 to
stop observing DST
• Both the EU and UK observed
DST in 2022
2018

88. DAYLIGHT SAVING TIME
• Good for the economy.
• Some reduction in crime.
(robberies reduced by 7%)
• Saves Energy.
• Changing manual clocks is
inconvenient
The shift to and from DST has been
likened to Jet Lag and linked to
increased rates of:
• Heart Attack (+25%)
• Vehicle Accidents (+17%).
• Workplace Accidents (+6%)
PROS CONS

89. COMPUTERS

90. COMPUTERS

91. TIME ZONE DATABASE
Time Zone Database
also known as:
• tz database
• tzdb
• zoneinfo database
• IANA Time Zone Database
• Olson database
• If your smartphone (Android or
iOS), laptop, server, or IoT
device runs a Unix/Linux based
Operating System, then it
almost certainly contains a
copy of the the TZ Database.

92. TIME ZONE DATABASE
What is the TZDB?
The database contains code and
data that represent the history of
local time for many representative
locations around the globe.
It is updated periodically to re
fl
ect
changes made by political bodies
to time zone boundaries, UTC
o
ff
sets, and daylight-saving rules.
1986

93. TIME ZONE DATABASE
• TZDB is an open source project run entirely by volunteers.
• Arthur David Olson has since retired. The current primary
coordinator is Paul Eggert, who has contributed to the
project since 1992.
2022

94. TIME ZONE DATABASE
An email to the TZ mailing list:
# From Heba Hamad (2022-03-10):
# summer time will begin in Palestine from Sunday 03-27-2022, 00:00 AM.
# Rule
NAME
FROM
TO
-
IN
ON
AT
SAVE
LETTER/S
Rule Palestine
2020
2021
-
Mar
Sat>=24
0:00
1:00
S
Rule Palestine
2020
only
-
Oct
24
1:00
0
-
Rule Palestine
2021
max
-
Oct
Fri>=23
1:00
0
-
Rule Palestine
2022
max
-
Mar
Sun>=25
0:00
1:00
S
Can quickly become a patch in the TZ Database:
2022

95. TIME ZONE DATABASE
# From Heba Hamad (2022-03-10):
# summer time will begin in Palestine from Sunday
03-27-2022, 00:00 AM.
# Rule
NAME FROM TO - IN ON AT SAVE
LETTER/S
Rule Palestine
2020
2021
-
Mar
Sat>=24 0:00
1:00 S
Rule Palestine
2020
only
-
Oct
24. 1:00
0 -
Rule Palestine
2021
max
-
Oct
Fri>=23 1:00 0 -
Rule Palestine
2022
max
-
Mar
Sun>=25 0:00 1:00 S
The source
fi
les contain a wealth of commentary that
provides useful context for the data.
The Zones and Rules are human readable,
even before they are compiled by the zic compiler.
2022

96. TIME ZONE DATABASE
• The TZ Database is a critical
part of the internet.
• The project was sued in 2011 by
Astrolabe Inc (makers of
Astrology software). The case
was dropped after support from
the EFF.
• A rift between maintainers
almost forked the project in
2021.
2022

98. THANK YOU
• Maintainers of tz@iana.org
• Wikimedia Commons
• UK Ordinance Survey
• Royal Greenwich Observatory
• Ted Grajeda @FreeVectorMaps
• Randall Munroe
John Dalziel
|
|
@crashposition
@computusengine
crashposition.com
computus.org
Happy Birthday Poppy x

99. BOOK RECOMMENDATIONS

100. LEAP SECONDS UPDATE
• Current models predict a negative Leap Second, but
probably not for a few years.
• November 15-18, 2022
BIPM General Conference on Weights and Measures
will discuss a resolution that would remove the
requirement to introduce new leap seconds.