The Date or Calendar Line is a modification of the line of the 180th meridian, and is drawn so as to include islands of any one group, etc, on the same side of the line.
When crossing this line on a westerly (true) course, the date must be advance one day; when crossing it on an easterly (true) course, the date must be put back one day.

Admiralty Hydrographic Department (1921)

In my last post on this topic, I brought the story up to the year 1900, when the International Date Line assumed a simple and elegant shape that was to persist, effectively unchanged, for almost a century—a zig-zag through the Bering Strait and around the Aleutians in the north, and a neat eastward shift around the Chatham Islands and Tonga in the south. But it actually took a while for the standard form of the Date Line to settle down into the shape I mapped out at the end of my previous post. So before I move on to other territories that have moved from one side of the Date Line to the other, I need to deal with the evolution of the shape of these northerly and southerly diversions.

TWO DIVERSIONS—PART 1. CHATHAM ISLANDS

Prior to 1910, the southern diversion around the New Zealand possession of the Chatham Islands followed a variety of curves, passing very close to the Chatham group. You can see an example in the chart from the paper “Where The Day Changes” (A.M.W. Downing. Journal of the British Astronomical Association, 1900), below:

And some more in the plots from a 1921 article produced by the Royal Navy’s Hydrographic Department, which was later reproduces as “Notes On The History Of The Date Or Calendar Line” (New Zealand Journal of Science and Technology, 1930). Here’s a detail from the original 1921 version:

Most early versions of the Date Line curved around very close to the east side of the Chathams. One (the Admiralty version from 1892-1910) seems to slice right through the middle of the group. But there appears to be no evidence that the Chathams ever used any dating system but Asiatic, in synchrony with New Zealand.

In 1910 the Hydrographic Department standardized the shape of the southern diversion, so that its eastern boundary ran along the 172.5ºW meridian. That style was copied by other cartographers, and has persisted to the present day.

TWO DIVERSIONS—PART 2. WRANGEL ISLAND

The northern end of the Date Line also took an unusual and confusing course on some maps, before it finally settled to its current form. For a while, on Royal Navy charts, it was shown following the 180º meridian right through the middle of Wrangel Island, in the high Russian Arctic. Along the whole length of the Date Line, Wrangel was the only piece of land it was depicted as traversing. So what was going on there?

In their book Plotting The Globe, Avraham Ariel and Nora Ariel Berger offer the story of Vilhjalmur Stefansson’s doomed attempt to plant a colony on Wrangel Island in 1921. The Soviet Union, the United States and the United Kingdom all had competing claims to this desolate spot —but Stefansson intended to use his colony to claim the island for Canada. When the Canadian government wisely decline the option, Stefansson decided to claim it for Britain instead. Four out of five of his original “colonists” died—the fifth, an Iñupiat woman known as Ada Blackjack, was rescued in 1923. (The full story of this tragic fiasco is told in Jennifer Niven’s book Ada Blackjack.)

Ariel and Berger offer this episode as an explanation for the Admiralty’s routing of the Date Line through Wrangel, claiming that:

[The British government] did not want to wrangle with the Soviet Union about Wrangel Island. The British Admiralty, however, quickly shifted the date line from its position east of Wrangel Island—which made it completely Russian—to the 180th meridian. The island was sliced into two date zones, as an initial recognition of a British-Canadian claim to at least its eastern part.

After Stefannson’s venture failed, and the Russians established a presence on the island to bolster their own claim:

Reluctantly the Admiralty returned the date line to its pre-1921 position in the Chukchi Sea, well east of the island.

This makes a great story, but Ariel and Berger don’t provide any references to support it, and it actually doesn’t make much sense.

• Military cartographers are well aware of the political implications of their charts, and are unlikely to jump the gun in the way described.
• The Date Line is not a territorial claim—there has, for instance, been a country (Kiribati, see below) that spent more than a decade with the Date Line running right through its middle, and no-one ever suggested that this divided it into two countries.
• No-one (including Stefansson) was ever claiming half the island—everyone wanted the whole of Wrangel. So splitting it down the middle exactly along the 180º meridian corresponded to no-one’s view of the situation.
• Stefansson, never one to underplay his own importance, makes no mention of this Date Line shift in his book, The Adventure of Wrangel Island (1925).

And, tellingly, we know for a fact that the Admiralty’s Hydrographic Department was running the Date Line to join the 180º meridian south of Wrangel Island long before Stefansson’s adventure. In 1900, the article “Where The Day Changes” contained a plot of the Date Line according to the Hydrographer of the Navy, Admiral William Wharton—it’s the solid line in the detail below, and it shows the Date Line terminating due south of Wrangel, on the 180º meridian.

(Another cartographer, Benjamin E. Smith, is responsible for the dashed line, which terminates east of Wrangel.)

And “Notes On The History Of The Date Or Calendar Line”, published by the Admiralty Hydrographic Department in November 1921, routes all of its versions of the historical Date Line, from 1892 onwards, straight across Wrangel on the 180º meridian:

Now, Stefansson’s “colony” was established in September 1921, but he kept his territorial aspirations a secret, at first. The fact that he claimed Wrangel for Britain was not revealed until March 1922, in an article in the New York Times*, well after the Hydrographic Department produced the map above. So it’s evident that, whatever the reason for the Admiralty’s routing of the Date Line through Wrangel, it predated Stefansson’s claims, and therefore had nothing to do with them.

What were they up to, then? I think the way Wharton’s line terminates non-commitally south of Wrangel tells us the answer—the Admiralty were trying to avoid even the implication of a territorial claim. Terminating the Date Line on the 180º meridian south of Wrangel was one way of avoiding the issue. If pressed, running the line north along 180º degrees as if Wrangel didn’t exist was another way of doing so—deviating it to the west could be interpreted as supporting a British or American claim; to the east could be interpreted as a vote for the Soviet Union.

Once the British government’s official position was that Wrangel was Russian territory (which was established in 1924), the Admiralty were free to move the Line east of Wrangel to reflect political reality—and it has been there ever since.

Now. On with the story of territories that have changed their calendars and crossed the Date Line.

KWAJALEIN (1969 and 1993)

Kwajalein Atoll is one of the many atolls that make up the Republic of the Marshall Islands. The Marshall Islands came under United States administration at the end of the Second World War, as part of the Trust Territory of the Pacific, and Kwajalein island (the largest island in the atoll) became the site of a large American military base, while the USA used the Marshall Islands as a site for atomic bomb and ballistic missile testing.

And then a curious thing happened in 1969. The Marshall Islands made a slight adjustment in their time zone, from GMT+11 to GMT+12—at midnight on Wednesday, 30 September, the Marshallese put their clocks forward by an hour, to 01:00 on Thursday, 1 October. Except, that is, for the inhabitants of Kwajalein Atoll (predominantly military personnel and support staff), who put their clocks back by 23 hours, to 01:00 on Wednesday, 30 September, thereby repeating a day and shifting across the Date Line to GMT-12. Their clocks remained in synchrony with the rest of the Marshall Islands, but their calendar was now one day behind. This was done so that the Kwajalein military base had the same working week as colleagues on the American side of the Date Line—office hours falling into approximate alignment on five days out of seven instead of just four.

Few cartographers bothered to mark this on the map, but the Date Line had just developed a little isolated loop of American dates, surrounded on all sides by Asiatic calendar.

The Marshalls became self-governing in 1979, and then fully independent in 1986—but the US military base was still there, and Kwajalein Atoll was still a day out of synch with the rest of the country. In 1993, the Marshallese government made a request to the US for Kwajalein to return to the same date as the other Marshall Islands. So Friday, 20 August 1993 was followed by Sunday, 22 August 1993. The residents staged a celebratory two-mile run that started just before midnight on Friday, and so took a whole day to complete—it was called the “Run Around The Clock”. Synchrony with the working week in the rest of the USA was maintained by the sort of solution only the military can impose—the working week on Kwajalein now starts on Tuesday and ends on Saturday, with Sunday and Monday being the official weekend.

Since the Marshall Islands were part of the Spanish possessions that shifted from the east to the west side of the Date Line in the nineteenth century, Kwajalein is the only territory in the world to have crossed the Date Line three times.

EASTERN KIRIBATI (1994)

Kiribati is pronounced “Kiribas” (the letter t is pronounced “s” in Gilbertese, and a final i is silent). It’s an island nation that straddles the 180º meridian, composed of the Gilbert Islands (west of the meridian, and once owned by the UK), and the Phoenix and Line Islands (east of the meridian, once claimed by both the UK and USA). The Gilberts used to keep Asiatic dates, while the Phoenix and Line Islands observed American dates. When the Gilberts became independent in 1979, the USA signed over the Phoenix and (most of) the Line Islands to this newly formed Republic of Kiribati (“Kiribas” being as close as it’s possible to get to saying “Gilberts” in Gilbertese).

So, this new country had the Date Line running right through its middle. The working week east of the Date Line did not match the working week in the Gilberts, the main population centre. So after putting up with this ridiculous situation for more than a decade, Kiribati adjusted itself so as to observe the same date throughout its territory—eastern Kiribati moved straight from Saturday, 31 December 1994 to Monday, 2 January 1995. (Pause for the obligatory joke: Haven’t we all had a Hogmanay like that?) The neat and minimalist International Date Line that had lasted almost a century suddenly developed a huge eastward panhandle as it routed itself around the Line Islands and their eccentric GMT+14 time zone.

While you might think this was all fine and sensible, it provoked an outcry, simply because of its timing. The new millennium was looming, and a (fairly minor) tourist demand had been created to offer a view of the first sunrise of the year 2000 (since everyone had decided that 2000 was the year the new millennium began, despite the cries of the purists). Kiribati had just shoved the Date Line so far towards the rising sun that it now owned the territory on which that sunrise was going to happen (if we ignore Antarctica). Uninhabited Caroline Island, in the extreme south-east of the Line Islands, was accordingly renamed Millennium Island.

At this remove, it’s difficult to credit the fuss that was made about a perfectly reasonable date adjustment. Pitt Island, one of the Chatham Islands (see above), had previously been the place that would greet the millennial sunrise, by virtue of being tucked up against the southern deviation in the Date Line. But neither the Chathams nor the Line Islands are particularly accessible, and both lack the facilities to support any major influx of sunrise tourists. So there wasn’t some huge financial implication underlying all this. And yet appeals were made to the United Nations (who said, in effect, “Nothing to do with us”) and the Greenwich Observatory (who said, in effect, “Well, that’s interesting, but nothing to do with us”).

Bizarrely, long after the event, Ariel and Berger devote a large part of a chapter in Plotting The Globe (2006) to exercising their outrage against Kiribati—expressions like “tricksters”, “chutzpah or desperation” and “has shown the world how the International Date Line can be prostituted” seem just a little overwrought, don’t they? They conclude that:

The international community has not taken the Kiribati adjustment seriously. World atlases still ignore Kiribati and show the International Date Line in that republic’s vicinity as it has been for the past century—a straight line congruent with 180º meridian.

I don’t know how many atlases they checked before they made this claim, but my Encyclopædia Britannica World Atlas from 2005 (the year before Plotting The Globe was published) certainly has the Kirbati deviation neatly plotted, as do most atlases published since.

SAMOA and TOKELAU (2011)

We left the Kingdom of Samoa, back in my previous post on this topic, having crossed the Date Line from west to east in order to improve trade relationships with the USA, and for its troubles having subsequently been divided up between Germany and the USA. From the start of the First World War, German Samoa passed into the hands of New Zealand, as the Western Samoa Trust Territory, and then became independent, as Western Samoa, in 1962. And then, in 1997, Western Samoa changed its name to just plain Samoa, much to the annoyance of American Samoa (still US territory), who felt that their neighbour wasn’t entitled to the full, unadorned title that had once applied to the original kingdom.

So the Samoa that now shifted back across the Date Line from east to west is actually only about half of the Samoa that originally shifted from west to east in 1892. The shift was again calculated to shift into alignment with the dates used by its main trading partners, which were now Australia and New Zealand. (In 2009, Samoa had made a shift from driving on the right to driving on the left—again, reflecting its ties to Australia and New Zealand, and falling into line with the practice of many of its island neighbours.)

The change took place at midnight on Thursday, 29 December 2011, which was followed by Saturday, 31 December.

The New Zealand dependency of Tokelau, three atolls with a total of just 1500 inhabitants, which lie immediately north of Samoa, elected to make the same calendrical switch on the same day. Tokelau’s transport hub is the island of Apia, in Samoa, and its administration is from New Zealand, so the shift made a lot of sense.

Interestingly, the Samoa-Tokelau Mission of the Seventh Day Adventist Church has refused to acknowledge the date change. This means that while Christian churches in Samoa and Tokelau are holding their Sunday services, Adventist churches are simultaneously observing their Saturday Sabbath—a situation that is probably unique in the world.

And that’s the story. So far.

* The article appeared on the front page of the New York Times of 20 March 1922:

STEFANSSON CLAIMS WRANGELL [sic] ISLAND FOR GREAT BRITAIN
The Expedition He Sent Out Last Fall Has Established Possession, Says Explorer.
TIMED TO FORESTALL JAPAN
Any Previous Claims of America or Britain Had Lapsed, He Holds.
NOW OFFERED TO CANADA
Stefansson Denies That Russia, to Whom the Island Is Allotted on Maps, Has Any Right to It.

The British flag has been raised by a party sent out by Vilhjalmur Stefansson on Wrangell Island, one of the most important islands in the Arctic region, because strategically it dominates Northeastern Siberia. The explorer now admits that when the little vanguard of his fifth and latest expedition, including citizens of the United States, landed on Wrangell Island, on Sept. 21 last, its mission was political as well as scientific.

Constrained by extreme necessity, we decided on touching at the Cape Verde Islands, and on Wednesday the 9th of July, we touched at one of those islands named St. James’s. […] In order to see whether we had kept an exact account of the days, we charged those who went ashore to ask what day of the week it was, and they were told by the Portuguese inhabitants of the island that it was Thursday, which was a great cause of wondering to us, since with us it was only Wednesday. We could not persuade ourselves that we were mistaken; and I was more surprised than the others, since having always been in good health, I had every day, without intermission, written down the day that was current.

Antonio Pigafetta, The First Voyage Round The World (c.1550)

Pigafetta sailed with Magellan’s small fleet, and was one of the few survivors who completed the circumnavigation. He recorded his experience in Italian (Relazione del primo viaggio intorno al mondo), and what he originally wrote has been pieced together from various surviving copies.

So he was one of the very first people to encounter a commonplace reality of modern long-distance travel. In the absence of an International Date Line (or even a general understanding of why a Date Line might be required), he found that his carefully recorded sequence of days and nights as experienced aboard ship had fallen out of synchrony with the days and nights of those who had stayed at home.

It works like this:
For a mythical observer sitting on the surface of the sun and watching the Earth revolve, we all of us go around the Earth once per day, carried around on its surface as it rotates from west to east. But anyone who travels across the surface of the Earth, making a circumnavigation from east to west, undoes one of the Earth’s rotations, and experiences one less day and night than those who stay at home. (This is why Pigafetta thought it was Wednesday when the Cape Verdeans thought it was Thursday.) Anyone who circumnavigates from west to east adds a rotation to the Earth’s natural period, experiences one more day and night, and comes back with their calendar a day ahead of those at home. (This famously supplied the twist at the end of Jules Verne’s novel, Around The World In Eighty Days.)

If we’re to keep everything straight, there needs to be a disjunction between time zones; a line at which we wind the calendar forward by a day when moving west, and turn it back by a day when moving east. And that’s the International Date Line, which runs down the middle of the Pacific, separating later dates in the west (“Asiatic” dates) from earlier dates in the east (“American” dates).

Interestingly, this International Date Line is nowhere defined in international law—you can’t look up a list of its precise coordinates.  In international waters, the nautical date line is well-defined—it follows the 180º meridian across the Pacific, and ships on the high seas will adjust their calendars as they cross that line. But in territorial waters, every sovereign territory chooses its own date, according to what’s most convenient. Since a number of countries in the Pacific lie directly on or close to the 180º meridian, the International Date Line must zig-zag back and forth around their territorial waters, according to which date they’re keeping. Cartographers plot a Date Line by choosing the most economical set of line segments they can find that keeps countries with Asiatic dates separate from those with American dates, and the precise choice of lines varies from one map-maker to the next.

From time to time, countries and territories have chosen to change the date they’re using, and the International Date Line then has to be flipped from one side of them to the other. And that’s what this post is about.

The Western calendar arrived in the Pacific aboard European ships. Some, mainly Spanish, arrived from the east (American) side of the ocean, and some arrived from the west (Asiatic) side. Those ships coming from the west had adjusted their clocks forwards as they sailed eastwards; those from the east had adjusted their clocks backwards as they sailed westwards—with the result that Asiatic and American time extended in a piecemeal fashion into the Pacific, and met up with their calendars a day out of synchrony. The date a territory first used depended on whether its first encounter with the Western calendar had come from the east or the west; the date it finally adopted depended on the dates its neighbours and trading partners were using. The following is a chronological list of those territories that started out with one date, and subsequently shifted to another.

PITCAIRN (between 1808-1814)

Pitcairn Island was colonized by mutineers from Captain William Bligh’s Bounty, along with their (not necessarily willing) Tahitian companions. The Bounty had entered the Pacific from the Asiatic side. The mutiny took place in the waters around what is now Tonga, after which the mutineers sailed their ship a long way east to Pitcairn, where they arrived in 1790. Their little colony was not discovered until 1808, when they were visited by the American sealing ship Topaz, which arrived from the American side of the Pacific. The next outsiders to visit the island arrived in 1814, aboard the British frigates Briton and Tagus. And this is when it gets interesting. In his narrative of the visit, Captain Philip Pipon of the Tagus records encountering the first-born son of the mutineer Fletcher Christian, whose name he gives as Thursday October Christian, named for the day and month of his birth. Whereas Marine Lieutenant John Shillibeer of the Briton, in his book A Narrative of the Briton’s Voyage to Pitcairn’s Island, describes meeting the same man, but gives his name as Friday Fletcher October Christian.

Thursday October Christian is certainly the name by which Fletcher Christian’s son was subsequently known. Did Shillibeer just make a mistake? This seems unlikely, since he spent a lot of time in Christian’s company, asking him questions and even making a drawing of him, which is reproduced in his book. So the man seems to have been called Friday, but to have adopted the name Thursday for use in later life. Which would make sense if the mutineers had carried their dates to Pitcairn from the west, and then subsequently found out from the American ship Topaz that their calendar seemed to be a day out of alignment. In which case Christian would have been born on Friday, 29 October 1790 by the Bounty’s calendar, but on Thursday, 28 October by the Topaz’s calendar. Pitcairn certainly now keeps the American dates appropriate for its position well east of the 180º meridian, but the story of Friday/Thursday Christian seems to suggest that it once used Asiatic dates, and made a change some time between the visit of the Topaz and the visit of the Tagus and Briton.

PHILIPPINES (1844)

The Philippines, despite their position very close to the Asian side of the Pacific, had their main calendrical contact with Spanish ships arriving from the Americas, with the result that the Philippines were, for three centuries, the tip of a peninsula of American dates which extended west into regions that otherwise observed Asiatic dates. Nineteenth-century maps show the Date Line with a huge westward bulge, encompassing not only the Philippines but other Spanish possessions in that part of the Pacific—the Marianas, the Carolines, the Marshalls and Palau. Here’s an illustration from Meyers Konversations-Lexicon, a German-language encyclopaedia, for instance.

But the Date Line in this map is inaccurately placed at Alaska (see next entry), and locates many islands farther south, like Fiji and the Cook Islands, on the wrong side of the line. So it’s more of an artist’s impression than an accurate depiction.

By the nineteenth century, Latin America was becoming independent from Spain, while Philippine connections with Asia and Australia were increasing. So at midnight on Monday, 30 December 1844, the Philippines flipped to an Asiatic calendar, by simply omitting 31 December entirely, and beginning the New Year in synchrony with neighbouring territories on Wednesday, 1 January 1845. Documentation seems to be lacking, but it seems likely that the Marianas, Carolines, Marshalls and Palau (which were governed from the Philippines) made the transition on the same date, allowing the Date Line to spring almost entirely back to the middle of the Pacific.

ALASKA (1867)

Alaska was owned by Russia until the Alaska Purchase of 1867, when the United States acquired the territory for $7,2000,000. Up to that time Alaska had been using Asiatic dates, to match Russia, with the Date Line running along the border between Alaska and Canada. To shift the Date Line westwards, into the Bering Strait, Alaska needed to repeat a day, bringing it into synchrony with American dates. But it was more complicated than that—Russia and Alaska were still using the old Julian calendar, whereas the USA (and most of the rest of the world) had moved on to the Gregorian calendar.* By the nineteenth century, the Gregorian calendar was 12 days ahead of the Julian.

So at midnight on Friday, 6 October 1867 (Julian calendar, Asiatic date), Alaska prepared to have another Friday, 6 October (Julian calendar, American date), but transformed into Friday, 18 October (Gregorian calendar, American date). This combined shift, with a duplicate weekday but a different date, appears to be unique in the annals of Date Line crossings.

With the shift of Pitcairn, the Philippines and Alaska to geographically appropriate dates, it began to look possible to run the Date Line fairly neatly through the middle of the Pacific, without too many zig-zags. The idea was clearly voiced at the International Meridian Conference of 1884, by one of the British representatives, Lieutenant-General Richard Strachey:

I think that if the world were to adopt the meridian of Greenwich as the origin of longitude, the natural thing for it to do would be to have the international day, the universal day, begin from the 180th meridian from Greenwich—that is, to coincide with the Greenwich civil day. That meridian passes, as I said before, outside of New Zealand, and outside of the Fijee Islands; it goes over only a very small portion of inhabited country. It appears to me, therefore, that inasmuch as there must be an absolute break or discontinuity in time in passing round the earth—a break of twenty-four hours—it is much more convenient that this break should take place in the uninhabited part of the earth than in the very centre of civilization.

The Meridian Conference firmly established the Greenwich meridian as the zero for longitude, but never got around to doing anything about formally defining the Date Line. But more calendrical adjustment was about to happen in the Pacific.

SAMOA (1892)

During the nineteenth century, the Kingdom of Samoa was keeping Asiatic dates, which had been established by missionaries originating in Australia. Britain, Germany and the USA were tussling for influence in the region. In 1892, the Americans managed to persuade King Malietoa Laupepa that increasing trade from San Francisco would be well served if Samoa shifted to the American side of the Date Line. And in any case, Samoa’s longitude of 172ºW put it on the American side of the critical 180º meridian. So Samoa shifted from Asiatic to American dates by having two American Independence Days in succession, repeating Monday, 4 July 1892.
But the story wasn’t over for Samoa, yet. In 1899, shortly after Malietoa Laupepa’s death, Germany and the USA divided up the Kingdom of Samoa between themselves, with Germany claiming the western islands (German Samoa) and America the eastern (American Samoa). That division into two colonial territories would become relevant later.

COOK ISLANDS (1899)

The Cook Islands got their calendar from Australian missionaries, too, and so ran on Asiatic dates. But at 160ºW, even farther east than Samoa, they were a long way into the American side of the Pacific, and they decided to shift their calendar to match that of their neighbouring territories. They made the change by repeating Monday, 25 December 1899. According to James Michener, the Cook Islanders enjoyed their two Christmases so much that they announced they would have made the transition years previously, if only someone had come up with this brilliant plan earlier.

“MORRELL ISLAND” AND “BYERS ISLAND” (1900)

These two islands were part of a vast archipelago, stretching from Hawaii to Japan, which appeared in early eighteenth-century charts. It was sometimes labelled the Anson Archipelago, and is distinguished by the fact that it was almost entirely imaginary or fictitious—very few of its islands actually existed, although all had been reported by more-or-less reputable mariners, sometimes on more than one occasion. But later in the century a lot of them were turning up absent when their location was revisited. So Captain Frederick Evans, newly appointed to the post of Hydrographer of the Royal Navy in 1875, went over the Pacific chart with a fine-tooth comb, and deleted no fewer than 123 of these islands (although a few had to be subsequently reinstated). Morrell and Byers Islands survived, temporarily, although marked “doubtful”. (In fact, almost everything about them seems to have been doubtful, from their existence and position to their correct names—Morrell also appears as Morell or Merrel, and Byers as Byers’s, Byers’, Byer’s, Byer and even Patrocinio.^†)

Their existence (or otherwise) was significant to the position of the International Date Line because they lay just off the western end of the Hawaiian island chain, were both claimed by Hawaii, and were both plotted just on the western side of the 180º meridian —174.5ºE and 176ºE, respectively. So the Date Line took a little jog westwards between 24ºN and 36ºN, to keep these two non-existent islands in the same American date zone as Hawaii. But as dubiety about their existence increase, cartographers began to straighten out the Date Line in that vicinity. This was a slow and piece-meal process—the islands were gone from some charts by 1903, but were still marked in J.G. Bartholomew’s Times Survey Atlas Of The World as late as 1922.

The Date Line shift associated with the vanishing of these islands is usually dated to 1910, based on a typewritten memorandum circulated by the Royal Navy Hydrographic Department in 1921,  which was reproduced in the New Zealand Journal of Science and Technology in 1930 as “Notes on the History of the Date Or Calendar Line“. This shows the course of the Date Line, as plotted by the Hydrographic Department over the course of the years, and the Morrell and Byers diversion is marked as persisting until 1910. (My picture below comes from a scan of the original, hand-illustrated Hydrographic Department document, which is clearer than the scanned version of the 1930 publication in my link above.)

But I’ve chosen 1900 as my cut-off date for Morrell and Byers because of an article about the International Date Line that appeared in the Journal of the British Astronomical Association in February 1900, written by A.M.W. Downing and entitled “Where the Day Changes“. It shows several plots of the Date Line, including one provided by Admiral William Wharton (Frederick Evans’s successor as Hydrographer of the Navy) which draws a straight line right past the fabled locations of Morrell and Byers. So it seems the Hydrographic Department had given up on that particular  Date Line diversion a little earlier than they subsequently recalled.

And of course it’s also a nice round number on which to pause this exposition. I’ll bring the story up to the present day in another post.

The story so far (click for an enlargement):

* If you want to know more about the Julian/Gregorian calendar shift, see my post about February 30th.
^† But we know that Morrell Island was named for its “discoverer”, Captain Benjamin Morrell, and (from Morrell’s memoir of his voyages), that Byers Island was named for James Byers, one of the owners of Morrell’s ship, Wasp. (Morrell used the form Byers’s Island.) Patrocinio is another illusory island, reported in the same vicinity by the Spanish Captain Zipiani in 1799. When Patrocinio could not subsequently be found at the coordinates Zipiani had set down for it, it was suggested that his was probably an earlier report of the island Morrell had named after Byers.