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Contents:
-
The
circumnavigator’s paradox
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The
discovery of the date line
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Some
17th-century
proposals for a date line
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The
course of the date line before the Philippine adjustment
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The
Philippine adjustment of 1844/45
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The
Alaska adjustment of 1867 and the Samoa adjustment of 1892
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The
date line before and after the International Meridian Conference (1884)
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The
Kiribati adjustment of 1994/95
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The
location of the IDL according to the Pacific Islands Pilot
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The
location of the IDL according to some major 20th-century
atlases
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References
The
circumnavigator’s paradox
What
appears to be the earliest reference to the circumnavigator’s paradox is found in
the works of the Syrian prince and geographer-historian Ismail ibn Ali ibn Mahmud
ibn Muhammad ibn Taqi ad-Din Umar ibn Shahanshah ibn Ayyub al Malik al Muayyad Imad
ad-Din Abu l-Fida (1273 - 1331). In his Taqwin al-Buldan (The ??? of the Lands),
Abu l-Fida described how a traveller, depending on his dircetion of travel, would
either lose or gain a day at the completion of his circumnavigation [Rudolf Wolf, Handbuch
der Astronomie, Ihrer Geschichte und Literatur (Zurich, 1890), vol 1, pp. 465-466;].
Another
early reference to the circumnavigator’s paradox is found in the works of the French
scholar Nicole Oresme (c. 1325 - 1382). In his Traitié de lespere (which
was also translated into Latin as the Tractatus sperae), Oresme presented a
remarkable circling of the Earth by two imaginary travellers Jehan and Pierre (Johannes
and Petrus in the Latin version) who set out to journey around the world along the
equator in opposite directions at a speed of 30 degrees of longitude per 24-hour day.
Jehan, travelling in a westward direction, would claim at the completion of his journey
that it took him only eleven days and nights while
Pierre
, travelling in an eastward direction, maintained that it lasted thirteen days and
nights. A third man, Robert, who had remained at the starting point, would however
point out that only twelve days and nights had elapsed since both travellers had set
out.
Oresme
repeated this argument in his Quaestiones supra speram, a series of clarifications
of questions based on the popular cosmographical treatise De sphaera by Sacrobosco,
in which he renamed his travellers Plato and Socrates and the control Petrus and allowed
both travellers a more leasurely pace of 14.4 degrees of longitude per 24-hour day.
At the return of the philosophers at the starting point, Plato (the westward traveller)
would have logged twenty-four days, Socrates (the eastward traveller) no less than
twenty-six days, while Petrus saw the sun rise and set only twenty-five times.
Around
1377 Oresme wrote his Traitié du ciel et du monde, a French translation and
commentary of Aristotle’s De caelo et mundo, in which he again discussed the
circumnavigator’s paradox. Here the westward traveller is simply named A, the eastward
traveller B and the control C. Each of both travellers is now assumed to cover 40
degrees of longitude per 24-hour day; A counting eight days for his circumnavigation,
B ten days, while C only marks nine days on his calendar.
In
order to resolve the circumnavigator’s paradox for future travellers, Oresme concluded
his discussion of the imaginary journeys of Plato and Socrates in the Quaestiones
supra speram with the observation:
‘From
this it follows that if this [equatorial] zone were everywhere habitable, one ought
to assign a definite place where a change of the name of the day would be made, for
otherwise Socrates would have two names for the same day and the other [Plato] would
have the same name for two days.’
The
discovery of the date line
It
was Antonio Pigafetta (c. 1490 - c. 1535), the Italian chronicler of
the first circumnavigation of the world by the Portuguese explorer and navigator Ferdinand
Magellan (c. 1480 - 1521), who first mentioned a peculiar incident that had
occurred during the voyage: somewhere a whole day had apparently been lost. When Pigafetta,
one of the eighteen survivors of the original 270-odd crew members who had set out
from the Spanish port of San Lúcar de Barrameda in September 1519, nearly three years
later sighted the Cape Verde Islands.
The
story of the lost day experienced by Magellan’s crew was also transmitted in a different
version by Pietro Martire d’Anghiera (1457 - 1526) in the 5th decade
of his De Orbe Novo (1530). This passage was translated by Richard Eden in The
Decades of the Newe Worlde or West India (1555) as:
‘And
amonge other notable thynges by hym [Peter Martyr] wrytten as touchynge that vyage,
this is one, that the Spaniards hauynge sayled abowt three yeares and one moneth,
and the most of them noytynge the dayes, day by day (as is the manner of all them
that sayles by the Ocean), they found when they were returned to Spayne, that they
had lost one day. So that at theyr arryuall at the porte of Siuile beinge the seventh
day of September, was by theyr accompt but the sixth day. And where as Don Peter Martyr
declared the strange effects of this thynge to a certeyne excellente man [Gaspari
Contarini of Venice (1483 - 1542)] who for his singular lernynge was greatly aduanced
to honoure in his common welthe and made Themperours ambassadore, this woorthy gentelman
who was also a greate Philosopher and Astronomer, answered that it coulde not otherwyse
chaunce unto them hauynge sayled three years continually, euer folowynge the soonne
towards the West. And sayde furthermore that they of owlde tyme obserued that all
suche as sayled behind the soonne towards the West, dyd greatly lenghten the day.’
Peter
Martyr’s lengthy discussions with Gaspari Contarini on this topic were summed up as:
‘Being
much disquieted and touched with that case, I conferred with Gaspari Contarini (a
man not meanly instructed in all kinds of literature), who was then ambassador with
the Emperor for his famous
commonwealth
of
Venice
. Whereby we know (discussing the matter with divers arguments) that this strange
report, never heard before, might very well be after this manner: This Castilian ship
set sail from the Islands of Gorgades [Cape Verde Islands] towards the west, which
way also the sun goeth. Thence it came to pass that having followed the sun, they
had every day longer according to the quantity of the way they made, wherefore having
perfited [encompassed] the circle, which the sun performeth in twenty-four hours towards
the west, it consumed and spent one whole day, therefore it had fewer days by one
than they who have that space of time kept one certain place of abode. But if the
Portugal fleet, which saileth toward the east, should return again unto the Gorgades,
continuing their course unto the east by this way and navigation, now first found
and discovered to mortal men, no man would doubt, seeing they should have shorter
days, having perfited the circle, but that twenty-four whole hours should remain unto
them over and above, and so one whole day, wherefore they should reckon more by one.
And so if either fleet, to wit, the Castilian and the Portugal, had set sail the same
day from the Gorgades, and the Castilian had sailed toward the west and the Portugal
had toward the east, turning stern to stern, and had returned to the Gorgades by these
divers ways in the same space of time and at the same moment, if that day had been
Thursday to the Gorgades, it had been Wednesday to the Castilian, to whom a whole
day was consumed into longer days. But to the
Portugal
, to whom by shortening of the days one day remained over and above, the same day
would be Friday. Let philosophers more deeply discuss this matter, we yield these
reasons for the present.’
Nearly
sixty years later, the same phenomenon was observed by the crew members of the fleet
of the English explorer Francis Drake (c. 1545 - 1596), when in September 1580
they arrived back again in
Plymouth
after a long westward voyage around the world that had started in late 1577.
‘The
22 day [of September] we were in the height of the Canaries. And the 26 of Sept. (which
was Monday in the iust and ordinary reckoning of those that had stayed at home in
one place or countrie, but in our computation was the Lords day or Sonday) we safely
with ioyfull minds and thankfull hearts to God, arrived at Plimoth, the place
of our first setting forth, after we had spent 2 yeares 10 moneths and some few odde
daies beside, in seeing the wonders of the Lord in the deep, in discouering so many
admirable things, in going through with so many strange aduentures, in escaping out
of so many dangers, and ouercomming so many difficulties in this our encompassing
of this neather globe, and passing round about the world, which we haue related.’
In
1594 the Venetian trader Francesco Carletti (1574 - 1636) set out on a remarkable
circumnavigation of the world in westward direction that lasted until the year 1606
and which he described in his Ragionamenti
del
mio viaggio intorno al mondo. Travelling without great haste via the Spanish dominions,
crossing the isthmus of Panama and stopping over at
Manila
, he booked a passage for the Japanese
port
of
Nagasaki
in 1597. Upon his arrival there he observed:
‘And
we found a difference in reckoning the days between us, who had come from the city
of
Manila
, and the Portuguese who had come from that of
Macao
, an
island
of
China
. These Portuguese, having left
Lisbon
and navigated constantly eastward, had reached
Japan
as the furthest point of their journeying. During their voyage, the sun having risen
for them constantly earlier, they had gained twelve hours of a natural day. We, on
the contrary, having left the
port
of
Sanlucar de Barrameda
in
Spain
and navigated steadily westward and having lost daylight constantly because the sun
kept rising later, had lost twelve hours. So when we discussed it with them, we found
that we had reached a difference of one day. And when they said it was Sunday, we
counted up to Saturday. Had I pursued my voyage around the entire world without having
met those Portuguese, by the time of my arrival in
Europe
, whence I first had departed, I should have lost exactly a whole day of twenty-four
hours.
For
I, having moved constantly from the east toward the west, changing meridians and therefore
making the day later for myself, would have encountered this difference of one day
as caused, as I have said, by the later or earlier rising and setting of the sun in
the diverse meridians, which continue changing daily for those who navigate toward
the east and toward the west. And it is true that in the Philippine Islands on that
same day when the Spaniards and their Church are celebrating Holy Saturday, those
who are in
Japan
- that is, the Portuguese and their Church - are eating meat, because for them it
is the day of the Resurrection. So that if they were moving swiftly enough to reach
Manila the next day, as is said to have happened to some navigators, they would celebrate
the same Easter or other solemnity twice. And if they were to arrive on the day when
those people celebrate the feast, it would befall them to return on Holy Saturday.
On the other hand, if those from
Manila
should set out on the day when they solemnize Christmas and reach the
island
of
Macao
, where the Portuguese are, they would find those others at the second feast of Saint
Stephen, and would thus celebrate one and another solemnity on the same day. And if
they were able to arrive on the day before Christmas by their count, they would be
able to eat meat without having fasted on the preceding day.
And
this suffices for knowledge of that occurrence, perhaps not better understood earlier
because the world had not been circumnavigated in olden times as it now is travelled
around by value and virtue of the two crowns of Castile and Portugal, who have showed
the way, the former navigating toward the east and reaching China and Japan, the other
toward the west and reaching these Philippine Islands, about one thousand mikes from
the island of Macao in China, the residence of the Portuguese. Together, those two
crowns have come to make a circle around the whole world ...’
Dutch
circumnavigators of the world also had similar experiences. When Isaac le Maire (??
- 1624), after an arduous voyage around the southern tip of South America (named Cape
Horn after the port of departure
Hoorn
), finally reached the
port
of
Batavia
on Java in November 1616, he noted in his journal:
‘This
[the confiscation of his ship and cargo by the authorities of the Dutch East India
Company] was done on Munday the first day of November, after our reckoning, but
upon a Tuesday the second of November by our Countrimens reckoning there. The reason
of the difference of time fell out thus – as we sayled westward from our own Countrey,
and had with the Sun compassed the Globe of the World, we had one night, or Sun-setting
less then they. [...] That weeke we lost the Tuesday, leaping from Munday to Wednesday,
and so had one weeke of six dayes.’
Some
17th-century proposals for a date line
In
1612 the French historian Nicholas Bergier (1567 - 1623) published a work entitled Archemeron
[Le point du jour], ou traicté du commencement des jours et de l’endroit où il est
étably sur la terre in which he proposed to adopt the meridian opposite to the
prime meridian of the renowned Flemish-German cartographer Gerard Mercator as a suitable
date line.
Apparently
unaware of Bergier’s earlier proposal, the Louvain humanist and scholar Erik de Put
(Erycius Puteanus, 1574 - 1646) published a work in 1632 in which he argued for the
adoption of a prime meridian running through Rome, which, in honour of the ruling
Pope Urban VIII, he proposed to name the Circulus Urbanianus. The meridian opposite
to that of
Rome
he named the Linea Archemerina and marked the line where the calendar date changed.
Puteanus
pointed out that in order to be useful a date line should pass only over water without
crossing any land and he conceded that his date line would have to make an eastward
excursion at the latitude of New Albion in order to satisfy this condition.
His
proposal was vigorously attacked by Giacomo Micalori (1570 - 1645), a professor of
theology and philosophy at Urbino, who described it as mancus, supervacaneus, imaginarius
et, ut omnia dicerentur, nullus [???]. Puteanus countered the objections from the
fool from Urbino in a work published in the following year that in turn was criticised
by Micalori in 1635. Though Puteanus received support from his friend Godfrey Wendelinus
and others, his proposal found little favour among cartographers with the exception
of his friend Michel-Florent van Langren (1598 - 1675), who around 1645 (or later)
published a 52½-cm terrestrial globe that depicted his meridians.
The
course of the date line before the Philippine adjustment
Early
19th-century
charts and globes never seem to have depicted the course of the date line across the
surface of the Pacific but in 1830 the German astronomer Heinrich Wilhelm Matthias
Olbers (1758 - 1840) gave the following verbal description of its approximate position:
‘Beyläufig
wird sie jetzt, vom Südpol kommend, östlich von Neuseeland und Neuholland [Australia]
entfernt bleiben, sich dann zwischen den Carolinen und Neuguinea hindurch nach Westen
biegen, die Philippinen und Marianen einschliessen, südöstlich von den Japanischen
und Kurilischen Inseln, und südlich von den Aleuten nach der Nordwestküste von America
streichen; diese Küste zwischen den Niederlassungen der Anglo-Amerikaner und der Russen
durchschneiden, und nicht weit östlich von diesen Russischen Colonien nach dem Nordpol
laufen. Dies ist ungefähr die jetzige Richtung und Figur der Linie, auf der derselbe
Tag zugleich anfängt und aufhört. Westwärts von dieser Linie zählt man als Datum und
Wochentag einen Tag mehr, als ostwärts.’
In
1830 the German sea-captain G. Wilcke from Stettin in Prussia (now Szczecin in Poland)
published a pamphlet entitled Abhandlung ueber die Annahme eines allgemeinen Kalendermeridians in
which he proposed to adopt the meridian passing through the middle of the Bering Strait
(which he determined to be 169º 01' West of Greenwich) as a suitable date line. Wilcke’s
proposal was reviewed for the Astronomische Nachrichten by Olbers, and although
he granted that the author showed good sense in choosing a meridian that passed mostly
over water and bisected only a few island groups, he was of the opinion that a fixed
date line was only of limited use and would be difficult to implement in an age when
one could not even agree on the choice of a common prime meridian.
The
Philippine adjustment of 1844/45
When
the British ex-buccaneer, sea-captain and explorer William Dampier (1651 - 1715),
during his travels across the globe from 1679 to 1691, weighed anchor after his stop-over
on the island of Mindanao in the Philippines in January 1687, he noted in his journal:
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‘It
was during our stay at
Mindanao
, that we were first made sensible of the change of time, in the
course
of our Voyage. For having travelled so far Westward, keeping the same Course with
the
Sun,
we must consequently have gained something insensibly in the length of the particular
Days,
but
have lost in the tale, the bulk, or number of the Days or Hours. According to the
different
Longitudes
of
England
and
Mindanao
, this Isle being West from the Lizzard, by common
Computation,
about 210 Degrees, the difference of time at our Arrival at
Mindanao
ought to be
about
14 Hours: And so much we should have anticipated our reckoning, having gained it by
bearing
the
Sun company. Now the natural Day in each particular place must be consonant to itself:
But this
going
about with, or against the Sun’s course, will of necessity make a difference in the
Calculation
of
the civil Day between any two places.
Accordingly,
at
Mindanao
, and all other places in the East-Indies, we found them reckoning a Day
before
us, both Natives and Europeans; for the Europeans coming eastward by
the
Cape of Good Hope
,
in
a Course contrary to the Sun and us, where-ever we met they were a full Day before
us in their
Accounts.
So among the Indian Mahometans here, their Friday, the Day of their
Sultan’s going to
their
Mosques, was Thursday with us; though it were Friday also with those
who came eastward
from
Europe
. Yet at the
Ladrone
Islands
, we found the Spaniards of
Guam
keeping the same
Computation
with our selves; the reason of which I take to be, that they settled that Colony by
a
Course
westward from
Spain
: the Spaniards going first to
America
, and thence to the Ladrones
and
Philippines
.’
As
explained by William Dampier, the erratic course of the date line across the waters
of
the
Pacific
Ocean
was the result of the way that the Pacific region had been explored and
colonised
by the various European powers during the 16th and
the 17th century.
In 1493 Pope
Alexander
VI issued a bull in which the meridian line located 100 leagues west of the
Cape
Verde
Islands
would divide the spheres of influence
of the Spanish crown (westwards of
the
demarcation line) and the Portuguese crown (eastwards of the same line). The
demarcation
line was moved to 370 leagues west of the
Cape Verde
Islands
in the following
year
by the Treaty of Tordesillas, sanctioned by Pope Julius II in 1506.
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European
explorers who
approached the
Pacific Ocean by
sailing to the
east such as the
Portuguese, and
in their wake
the Dutch, the
English and the
French,
naturally kept
their ship’s
journals and
diaries
according to the
day count of
their home land
and this was of
course also
adopted by the
colonists who
settled along
the Asian
perimeter of the
Pacific Ocean.
However,
the colonisation of the Pacific Ocean by the Spanish occurred from the opposite direction
and more specifiically from the Spanish possessions in
America
. The Philippine archipelago was discovered in March 1521 by Ferdinand Magellan and
Spanish dominion over the islands was first firmly established in 1565 by Miguel López
de Legazpi (c. 1510 - 1572), the conquistador and first Spanish governor general
of the
Philippines
. He had been equipped with five ships by Luis de Velasco, the viceroy of New Spain,
and left
Acapulco
in 1564. In April 1565 he reached Cebu, one of the southern islands of the archipelago,
and founded the first Spanish settlement on the site of modern
Cebu
City
. In 1570 he sent an expedition to the northern
island
of
Luzon
and in the next year he founded the city of
Manila
, which became the capital of the new Spanish colony and
Spain
’s major trading port in
East
Asia
.
Most
of the shipping from the
Philippines
to
Spain
went over the Pacific Ocean to the Mexican
port
of
Acapulco
, was transported over land to the
port
of
Veracruz
, and then shipped to
Spain
. In order that the Spanish ships crossing the Pacific Ocean between the Philippines
and the Spanish America’s would not have to adjust the dates in their journals whenever
they sighted land, the Philippines observed the same day count as that of the Spanish
America’s.
The
Philippine tradition of counting the days according to the American reckoning could
sometimes fool the unwary traveller. In 1590 the Spanish historian José de Acosta
described the following in his Historia Natural & Moral de las
Indias
:
‘It
happened to Father Alonse Sanches [...], that parting from the Philippines, he arrived
at Macao, the second day of Maie, according to their computation, and going to say
the Masse of S. Athanasius, he found they did celebrate the feast of the invention
of the Holy Crosse, for that they did then reckon the third of Maie.’
During
the early 1840’s the commercial interests of the Philippine Islands turned more and
more away from the Spanish America’s (which for a large part had severed their relations
with the mother land Spain) and trading with the Chinese mainland (engendered by the
ignominious but lucrative Opium Wars), the Malay peninsula, the Dutch East Indies
and Australia became increasingly important.
In
order to facilitate communication and trading with its western and southern neighbours,
the secular and religious authorities of the
Philippines
agreed that it would be advantageous to abolish the American day reckoning and adopt
the Asian day reckoning.
This
was achieved in 1844 when Narciso Claveria, the governor general of the
Philippines
, issued a proclamation announcing that Monday, 30 December 1844, was to be immediately
followed by Wednesday, 1 January 1845.
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