1.
Cultural Heritage Dates
Understanding the provenance of an artwork.
David Newbury
@workergnome

2.
What is Art Tracks?
Art Tracks is a research project
at the Carnegie Museum of Art.

3.
What is Art Tracks?
Art Tracks is a research project
at the Carnegie Museum of Art.
We're digitizing the history of ownership of art.

4.
Oldest item
Vase
MESOPOTAMIAN, SUSA
(C. 3000 BCE-2000 BCE)
painted earthenware
Walter Read Hovey Collection

5.
Newest item
My Heart Is Not Here My Heart's
in The Highlands Chasing The Deers
Rokni Haerizadeh
(2013)
gesso, ink, and watercolor on printed paper
The Henry L. Hillman Fund

6.
Museums are full of art.
Art is culture.
Art is also stuff.

7.
Stuff has a history.
— Created by an artist
— Sold to collectors
— Given to children
— Sold at auctions
Eventually,
it ends up at a museum.

8.
The record of this is called
Provenance.

9.
Provenance is a chain of ownership.
Every time a painting changes hands,
it's a new link in that chain.

10.
Water Lilies (Nymphéas)
Claude Oscar Monet [1840-1926]; Estate of Claude
Oscar Monet; Michel Monet, son of the artist, Sorel
Moussel, Dept. Eure et Loire, 1926 until 1950; Walter P.
Chrysler, Jr. [1908-1988], New York, NY, 1950 until 1962;
purchased by Museum, April 1962.

11.
What Data?

12.
The Person
Name
Birth
Death
Location
Portrait of Isabella de' Cosimo I de Medici
C. 1570-1574
Alessandro Allori
oil on canvas (transferred from panel)
Gift of Mrs. Paul B. Ernst

13.
The Transfer
Acquisition Method
Direct Transfer
Auction
Harry Shokler
1942
silkscreen on paper
Leisser Art Fund

14.
Metadata
Stock numbers
Footnotes
Primary ownership
Footed bowl
C. 1925
OTTO LINDIG (GERMAN, 1895–1966)
earthenware
Gift of Barry Friedman, Ltd.

15.
Dates
Acquisition
Deacquisition
Persimmon (Kaki)
MAKI HAKU (JAPANESE, 1924–2000)
woodcut with embossing on paper
Bequest of Dr. James B. Austin

16.
Dates are not a thing
A date is a string representation
of a particular moment of time.
...At a particular location.
...On earth.

17.
Easy Date Problems:
12/4/2014:
December 4th or April 12th?
Depends on your national standard. Don't do this.
ISO 8601 is what you want.
2014-12-04T00:00:00

18.
Medium Date Problems:
2014-12-04T00:00:00:
December 4th or December 3rd?
Depends on your location. Use UTC.
Time zones matter.
2014-12-04T00:00:00Z

19.
Hard Date Problems:
October 6th, 1582
Exists in England.
Doesn't exist in Italy.
Date.new(1582,10,5)
# ArgumentError: invalid date
Date.new(1582,10,14,Date::ENGLAND)
# <Date: 1582-10-14 ((2299170j,0s,0n),+0s,2361222j)>
fantastic trolling opportunity here for tests.

20.
Harder Date Problems:
What year comes before 1 AD?
— 0 AD?
— 1 BCE?
St. George and the Dragon
YUGOSLAVIAN
C. 1500
oil on panel
Gift of Dr. Walter Read Hovey

21.
Choosing an Epoch

22.
Unix Time
Seconds since 0h Jan 1, 1970
DateTime.new(2014,12,4,20,0,0).to_time.to_i
# => 1417723200
Valid between December 13, 1901 and 19 January 2038.

23.
Gregorian
The way you learned dates in school
valid since Oct 15, 1582
DateTime.new(2014,12,4,20,0,0).to_s
# => "2014-12-04T20:00:00+00:00"

24.
Julian Day
The way Ruby represents dates
days since 12h Jan 1, 4713 BC
DateTime.new(2014,12,4,20,0,0).jd
# => 2456996

25.
Heliocentric Julian Day
The current day.
On the sun.

26.
Barycentric Julian Day
The current day.
At the center of the solar system.

27.
Dates in Ruby
Mug
TOBIAS BAUER (GERMAN)
1695-1705
blown, gold-ruby glass w/silver-gilt mounts
DuPuy Fund

28.
Time
— Based on (and implemented in) C
— Counts seconds from Unix Epoch
— Compatible with Unix and other languages
— Fast

29.
Date && DateTime
— Written in Ruby
— Counts days from Julian Epoch
— Slower

30.
Internal Implementation
if you #inspect a DateTime:
DateTime.new(2014,12,4,20,0,0).inspect
# <DateTime: 2014-12-04T20:00:00+00:00 ((2456996j,72000s,0n),+0s,2299161j)>

31.
DateTime: 2014-12-04T20:00:00+00:00 ((2456996j,72000s,0n),+0s,2299161j)
2014-12-04T20:00:00+00:00
the current time in ISO 8601.

32.
DateTime: 2014-12-04T20:00:00+00:00 ((2456996j,72000s,0n),+0s,2299161j)
2456996j The number of days since the Julian Epoch
+
72000s some number of seconds
+
0n some number of nanoseconds

33.
DateTime: 2014-12-04T20:00:00+00:00 ((2456996j,72000s,0n), +0s ,2299161j)
+0s
The offset in seconds from UTC time

34.
DateTime: 2014-12-04T20:00:00+00:00 ((2456996j,72000s,0n),+0s, 2299161j )
2299161j
The day of the Gregorian Reform.

35.
Imprecise Data.
Computers hate imprecision.
Apr. 27, 1978
ON KAWARA (JAPANESE, 1932–2014)
1978
Liquitex on canvas
A. W. Mellon Acquisition Endowment Fund and Carnegie
International Acquisition Fund

36.
Precision
— January 1, 1900
— January 1900
— 1900
— the 1900s
— the 20th Century
What is the difference?

37.
date_time_precision gem
https://github.com/Spokeo/date_time_precision
Extends Ruby Date, Time, and DateTime to include
the notion of date precision.

38.
require 'date_time_precision
year = DateTime.new(1990)
=> #<DateTime: 1990-01-01T00:00:00+00:00 ((2447893j,0s,0n),+0s,2299161j)>
year.precision
=> 1 # or DateTimePrecision::YEAR
year.day?
=> false
year.year?
=> true

39.
Persists via copy
new_year = year
=> #<DateTime: 1990-01-01T00:00:00+00:00 ((2447893j,0s,0n),+0s,2299161j)>
new_year.precision
=> 1

40.
Needed to handle DECADE && CENTURY precision
year = DateTime.new(1755)
year.decade
=> 1750
century = year
century.precision = DateTimePrecision::CENTURY
year.century
=> 1700

41.
Custom Extensions for Date#earliest && Date#latest
year = Date.new(1755)
year.earliest
=> Wed, 01 Jan 1755
year.latest
=> Wed, 31 Dec 1755
century = Date.new(1800)
century.precision = DateTimePrecision::CENTURY
century.earliest
=> Wed, 01 Jan 1800
century.latest
=> Sun, 31 Dec 1899

42.
Ontologies
Modeling the data.

43.
...
What is the CIDOC CRM
The CIDOC Conceptual Reference Model (CRM)
provides definitions and a formal structure for
describing the implicit and explicit concepts and
relationships used in cultural heritage documentation.
— http://www.cidoc-crm.org

44.
A Timeline represents the
entire history of ownership of a single work.

45.
A Period is a single period in time
representing an single owner of a work.

46.
Beginnings & Endings

47.
George, 1950; Mary 1965.

48.
George, by 1960 until sometime after 1962; Mary, in 1970.

49.
John Doe, 1995

50.
John Doe, by 1995

51.
John Doe, after 1995

52.
John Doe, until 1995

53.
John Doe, until at least 1995

54.
John Doe, until sometime before 1995

55.
John Doe, in 1960

56.
John Doe, 1950 until 2000

57.
require 'museum_provenance'
text = "sold December 1936 to Robert Doe, Pittsburgh"
period = MuseumProvenance::Period.new()
puts period.parse_time_string(text)
# => sold to Robert Doe, Pittsburgh
puts period.beginning.to_s
# => December 1936
puts period.beginning.earliest
# => 1936-12-01
puts period.beginning.latest
# => 1936-12-31
puts period.ending.to_s
# => nil

58.
Why all this work?

59.
Nazi War Crimes.

60.
Thank You.
https://github.com/cmoa/museum_provenance
David Newbury
@workergnome