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Posts Tagged ‘Great Barrier Reef

Joshua Slocum in Google Earth: Thursday Island to Christmas Island

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

A few days after the celebrations on Thursday Island to mark Queen Victoria’s diamond jubilee, Slocum sets sail. He heads westward, out into the Arafura Sea, passing Booby Island on the way. He has seen the island before, about 30 years back, but then he was in a fever (possibly contracted in Batavia for his ship, the Soushay, was Sydney-bound from that port), and it was only through an act of will that he dragged himself on deck to see it.

While the sea is relatively shallow he sees many sea snakes writhing and tumbling in the waves and, because the waning Moon leaves the nights dark, he is treated to a fiery display of phosphorescence¹:

It was my good fortune to enter the [Arafura] sea on the last quarter of the moon, the advantage being that in the dark nights I witnessed the phosphorescent light effect at night in its greatest splendour. The sea, where the sloop disturbed it, seemed all ablaze, so that by its light I could see the smallest articles on deck, and her wake was a path of fire.

The weather is serene and the trade winds favourable. Slocum takes this northerly route in order to enjoy these conditions; he has no desire to go around the Cape of Good Hope before the middle of the southern summer and he finds that this plan gives him the time to loiter among the islands along the way.

Even so, as an inveterate sailing ship master he wants to get the best speed out of his vessel. For whatever reason he is dissatisfied with the Spray‘s pace and to remedy this he sets his flying-jib as a spinnaker², using as a pole “the stoutest bamboo that Mrs. Stevenson had given me at Samoa.”

As in the Pacific, the Spray holds her course with remarkable accuracy and for days on end he finds the latitude at noon to be 10° 25’S.

By 02Jul1897 Slocum sees the island of Timor to the north; the next day he passes close by Dana Island off the western end of Timor and smells the fragrances wafted offshore by a breeze. He has crossed the Timor Sea and he enters the Indian Ocean heading for Christmas Island about 1,000 miles distant, arriving eight days later on 11Jul1897.


The section of Joshua Slocum’s journey reported here concludes Chapter XV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. Using  TourMaker I simulated the phosphorescence that Slocum saw by stretching out a white strip to keep pace with the Spray.

2. I needed to create another model to show the flying-jib set as a spinnaker. While I was about it I swung out the mainsail boom to give a goose-wing effect.

Copyright © Colin Hazlehurst, 2012

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Joshua Slocum in Google Earth: Cooktown to Thursday Island

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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Slocum sails from Cooktown on 06Jun1897 and by the evening of the 7th the Spray is at anchor near the Claremont Islands. Apart from in harbour at Port Denison and Cooktown, this is the only time Slocum anchors in the Barrier Reef Channel. By the next evening he wishes it isn’t. The Spray is sailing into the night at full speed ahead and passes the light-ship at the southern end of ‘m’ reef.¹ He expects there to be a beacon light at the north point; if there is one he doesn’t see it and the Spray strikes the reef. The next swell carrier her safely over but not before Slocum sees the ugly sharp coral rocks and realises just how lucky he is.

Keeping further out to sea now, heeding the advice to keep clear of the residents of Cape Grenville,  Slocum passes outside all of the islands including Home Island off the tip of the cape itself. He squares away westward in the direction of Sunday Island and shortens sail as he passes it; he doesn’t want to reach Bird Island before daylight — that island group is low-lying and surrounded by navigational hazards. On the morning of the 9th Bird Island is only 2.5 miles ahead, so he was lucky again that the current carrying him along was not stronger.

He spends the rest of the day sailing from Bird Island to Cape York, navigating Albany Pass, between mainland Australia and York Island, “as the sun drew low in the west over the hills of Australia.”

He anchors in a cove near the Tawara, an American built and skippered pear-fisher. Next day, he spends a pleasant few hours with the crew of Tawara and with the Jardine family from nearby Somerset. It turns out that Mrs. Jardine is cousin to Faamu-Sami, princess of Samoa and daughter of King Malietoa, who had visited the Spray at Apia.

From this cove, Slocum makes the short trip into the Torres Strait across to Thursday Island. He finds that celebrations are planned for Queen Victoria’s diamond jubilee on 22Jun1897, and doesn’t need much persuading to extend his visit here.


The section of Joshua Slocum’s journey reported here continues Chapter XV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. On the evening of 08Jun1897, the Spray struck a reef and luckily there was enough water for the next swell to carry her over it. Slocum identifies this as ‘M Reef’; however, a search of the web delivers no information about the location of this hazard. I didn’t want to use a random reef in the animation so I had to dig further until I found an online version of a chart compiled from mid-19th century surveys by the Great Britain Hydrographic Department. The chart is made available by the National Library of Australia.

British Hydrographic Department chart showing the reefs of the Barrier Reef Channel

By close examination of the chart, I was able to find the identification letters of the significant reefs that skirt the Barrier Reef Channel. I couldn’t find all of them but at least it was clear which is ‘m’ reef.

To help anybody else who is looking for reefs in the Barrier Reef Channel using their identification letter, I have plotted them in Google Earth and kept their labels visible throughout the animation.

2. This chapter of Slocum’s book is one in which a lot of ground is covered with relatively few words. I like the animation of the model Spray to coincide with the narrative so, at times, it is necessary to move the model to a new location without accompanying voice-over. This can seem like an awkward silence and to overcome it I use two techniques:

  • The background sound effect of water lapping against the hull; if nothing else this helps to distract sufferers of tinnitus from their condition, and it does seem to work.
  • Using the ‘Show’ directive of TourMaker, I pop up labels that identify significant landmarks like capes, islands, and bays.

3. I am using an unabridged version of Sailing Alone Around the World. There are a few places where I have chosen not to speak the words that Slocum wrote as they are offensive to the modern ear. This chapter includes one such passage in which he describes the appearance of the men and women who travelled over to Thursday Island for the jubilee celebrations.

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: Whitsunday Passage to Cooktown

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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Captain Cook, taking Endeavour through Whitsunday Passage (named by him because 03Jun1770 was Whit Sunday), sailed through the night and arrived the following morning at: “a lofty promontory that I named Cape Gloucester”.

Joshua Slocum, a few days short of 127 years later, passes here on 26May1897. His charts show more accurately than Cook’s survey that the promontory is actually detached from the mainland and is now called Gloucester Island. The Spray hauls into the bay to the west of the island and anchors at Port Denison, close to the small town of Bowen.

Bowen at that time has a population of around 1,000; large enough to support a keen audience for Slocum’s story.

By 31May1897, the Spray, has carried Slocum safely through 350 miles of the Great Barrier Reef. Without anchoring anywhere, Slocum sails past many of the other capes, bays, and islands named by Cook:

  • Cape Upstart
  • Cape Cleveland
  • Cleveland Bay
  • Cape Richards
  • Rockingham Bay
  • Cape Grafton
  • Fitzroy Island
  • Cape Tribulation (“for here all my troubles began”)

Cook also named the Endeavour River, for it was here that H.M.Bark Endeavour was beached for repairs after she had struck a reef just north of Cape Tribulation (the reef was named unsurprisingly Endeavour Reef).

Cooktown was certainly in existence before the gold rush of the 1870s, when the settlement grew rapidly as a supply port, because Slocum reports visiting on the steamship Soushay in 1866; he didn’t see much of it at that time because he was ill with a fever.

The “lecture tour” continues when a meeting is arranged in the Presbyterian church and Slocum delivers his “story of the sea.”


The section of Joshua Slocum’s journey reported here opens Chapter XV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: South Solitary Island to Whitsunday Passage

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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After exchanging signals at South Solitary Island, Slocum continues north and on 19May1897 sails past Point Danger, named by Captain Cook after his encounter with shoals and strong currents there.

On the 20th, the Spray rounds Sandy Cape, a significant point that marks the beginning of the Great Barrier Reef. The light on Sandy Cape is visible for 27 miles and his next way point is the Lady Elliot Island light. This is important to find because Slocum is heading into a dangerous region shoals and reefs and all the charts in the world are of little use if you don’t know where you are. Lady Elliot Island is about 45 miles from Sandy Cape but it seems to take an endless time to cover that distance. Slocum concludes he is pushing against a strong current.

The Spray had sailed for hours in suspense, evidently stemming a current. Almost mad with doubt, I grasped the helm to throw her head off shore, when blazing out of the sea was the light ahead. “Excalibur” cried “all hands,” and rejoiced, and sailed on.

So he finds the light on Lady Elliot Island¹ and passes into the serene, but still risky, waters inside the Great Barrier Reef and is protected from the worst of the Pacific Ocean’s waves. Progress is good and the Spray averages 4.6knots over the next four days:

On the 24th of May, the sloop, having made one hundred and ten miles a day from Danger Point, now entered Whitsunday Pass, and that night sailed through among the islands. When the sun rose next morning I looked back and regretted having gone by while it was dark, for the scenery far astern was varied and charming.


The section of Joshua Slocum’s journey reported here concludes Chapter XIV of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

Notes

1. The  technical challenge in this part of the presentation was to simulate the light from the Lady Elliot Island lighthouse. I wanted to create a beam of white light that rotates about the location of the lighthouse; furthermore, I wanted it to have the same characteristic as the current light, which is described on charts as: Fl.W. 7.5s. This code means that the light is white and flashes every 7.5 seconds.

To achieve this I needed two things:

  • A model to animate.
  • A TourMaker directive to generate the animation.

I created the beam of light by drawing a cone in Google Sketchup and colouring it white. The cone was about a mile long, oriented along the green axis, which is north when the model is exported to Google Earth, and its apex was placed about 100 feet above the origin.

In the KML file for this leg of Slocum’s journey, I added the model as a Placemark, positioning it at the latitude and longitude of the Lady Elliot Island lighthouse (at the south end of the island). I set the visibility of the Placemark initially to zero (invisible), because I wanted to ‘turn on’ the light at the instant in the narrative that Slocum sees it.

To simulate a rotating beam I would need to animate the model by changing its orientation. By placing the origin of the model at the position of the lighthouse, a change in its orientation would have the desired effect of a light sweeping round.

I measured the angle subtended by the model and found that the edges of the cone were 15° apart. To achieve a smooth rotation, I would want each new orientation of the model to be no more than 15° away from the last one. I also knew that the beam should sweep through 360° in 7.5 seconds, in other words its angular velocity should be 360/7.5 degrees per second, which  comes out at 48° per second.

I used this information to determine how many orientation changes per second would be required to generate a smooth animation at the required rotation rate. Quite simply, if each animation step rotates the model by 15° and we need to rotate the model at 48° per second, then we need 48/15 animation steps per second (3.2), so the duration of each animation step should be 1/3.2 seconds (0.312s).

All of this is easy to code, taking only a few hours of development and testing. To control this behaviour, I added a ‘Rotate’ directive to TourMaker, and its parameters identify which model to animate, the duration of the animation, the angular velocity required, and the delay until the animation should start. This last parameter allowed me to switch on the beam as the narration reads:

Almost mad with doubt, I grasped the helm to throw her head off shore, when blazing out of the sea was the light ahead

The animation starts at the word ‘blazing’; the Placemark is made visible, the light sweeps around for 30 seconds and the Placemark is then made invisible.

Copyright © Colin Hazlehurst, 2012

Joshua Slocum in Google Earth: Waterloo Bay, St. Kilda and Launceston

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Follow Joshua Slocum’s Sailing Alone Around the World at: http://www.hazelhurst.net/Slocum

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Joshua Slocum shelters for three days in Waterloo Bay on Wilson’s Promontory in the company of a few whaling boats. Then, in more moderate weather, he sails to Melbourne and picks up a tow at the entrance to Port Phillip Bay. On Christmas Day, 1896, the Spray is anchored in the Yarra River (which he calls the Yarrow), but Slocum soon moves to St. Kilda.

He catches a shark and puts it on display, along with the 26 cubs born by Caesarean section. He charges sixpence per visitor, having set up this enterprise to cover the cost of port charges incurred here. Apart from at Pernambuco (Recife) in Brazil, where he has some history with the regime, these are the only other fees he has to pay on the whole voyage.

News comes in of unusually large amounts of Antarctic ice drifting northwards, bringing with it much stormy weather. Slocum’s plans change again. Rather than head west to battle around Cape Leeuwin he opts to spend time in Tasmania while the season’s change enough to make an easy passage through the Torres Strait; in other words, he intends to sail up the east coast of Australia inside the Great Barrier Reef, where, reaching warmer waters, he would sail round Cape York and into the Indian Ocean.

He sails from St. Kilda on 24Jan1897 and in strong and favourable winds it’s only a two-hour trip across to Tasmania. He reaches the mouth of the Tamar River and follows its meanderings up to Launceston which is about 30 miles inland. The Spray is grounded, on account of arriving at the top of an exceptionally high tide and she eventually has to be dug out:

The Spray was berthed on the beach at a small jetty at Launceston while the tide driven in by the gale that brought her up the river was unusually high; and she lay there hard and fast, with not enough water around her at any time after to wet one’s feet till she was ready to sail; then, to float her, the ground was dug from under her keel.

In this snug place I left her in the charge of three children, while I made journeys among the hills and rested my bones for the coming voyage, on the moss-covered rocks at the gorge hard by, and among the ferns I found wherever I went.


The section of Joshua Slocum’s journey reported here concludes Chapter XIII of Sailing Alone Around the World, and this post is a trailer for the adventure that I am retelling in Google Earth at:  http://www.hazelhurst.net/Slocum

To ‘sail’ the 3D model of the Spray up the Tamar to Launceston is not something I would have attempted without the use of the TourMaker tool. The model has to follow the meandering of the river and to be scaled appropriately, and this would have been very laborious to create using hand-written <gx:tour> directives.

Using TourMaker, I was able to create a series of Placemarks, positioned along the course of the river, and generate the tour automatically. Now, of course, I will need to get the Spray down the river again, but using the same Placemarks in reverse order, this should be quite straightforward.

Copyright © Colin Hazlehurst, 2012

You might also enjoy Cook’s first voyage round the world at: http://www.hazelhurst.net/Cook

Captain Cook in Google Earth: Fevers and Fluxes

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His Majesty’s Bark Endeavour arrived in Batavia, Java, on 10th October, 1771. At this point in the voyage, more than 3 years after setting sail from Plymouth, the ship was in a very poor state and in need of a major refit. John Satterly, the ship’s carpenter provided Lieutenant Cook with a description of her defects, the majority of the damage being inflicted when Endeavour ran aground on a reef off Australia:

The ship very leaky (as she makes from 12 to 6 inches water per hour) occasioned by her main Kiel being wounded in many places and the Scarfe of her Stem being very open. The false Kiel gone beyond the Midships from Forward and perhaps further, as I had no opportunity of seeing for the water when hauled ashore for repair. Wounded on her Starboard side under the Main Chains, where I imagine is the greatest leaks (but could not come at it for the water).

By contrast, the men in were in good condition. The diet of his crew was constantly on Cook’s mind and he made every effort to procure fresh produce whenever possible. His journal entry for 15Oct1771 reads:

Monday, 15th. Fresh Sea and land breezes and fair weather. I had forgot to mention that upon our arrival here I had not one man upon the sick list; Lieut. Hicks, Mr. Green, and Tupia were the only people that had any complaints occasioned by a long continuance at Sea.

This was a great success considering the hardships, both physical and psychological, the men had endured. However, a mere 3 weeks after returning to ‘civilisation’ from the privations that attended their voyage of discovery the picture was very different. On Wednesday, 07Oct1771 Cook wrote:

Wednesday, 7th. Employ’d getting ready to heave down in the P.M. We had the misfortune to lose Mr. Monkhouse, the Surgeon, who died at Batavia of a Fever after a short illness, of which disease, and others, several of our people are daily taken ill, which will make his loss be the more severely felt; he was succeeded by Mr. Perry, his mate, who is equally as well skilled in his profession.

And another 3 weeks after this:

Wednesday, 26th. The number of Sick on board at this time amounts to 40 or upwards, and the rest of the Ship’s Company are in a weakly condition, having been every one sick except the Sailmaker, and old Man about 70 or 80 years of age. But notwithstanding this general sickness, we lost but 7 men in the whole: the Surgeon, 3 Seamen, Mr. Green’s servant, and Tupia and his servant, both of which fell a sacrifice to this unwholesome climate before they had reached the object of their wishes.

You have to feel for these men; they had rounded Cape Horn against wind and tide; they had taken their ship across the Pacific to Tahiti to observe the transit of Venus, then turned south to face more violent storms in search of a suspected southern continent; they had circumnavigated both North Island and South Island of New Zealand again with heavy swells and storm force winds; they sailed the whole of the east coast of Australia, sounding with a lead most of the way; they survived the grounding of the ship on the Great Barrier Reef when only their efforts at pump and windlass saved them; they proved there was a passage between Australia and New Guinea; and with a ship that was battered and worm-eaten they had limped to Batavia.

These giants of adventure were laid low by the microscopic organisms of dysentery: viruses, bacteria, protozoans, and parasites of various types. Too little was known of the mechanisms of dysentery and the preventive measures against it and they paid the price. The illness had no respect for rank; Mr. Monkhouse, the ship’s surgeon, Charles Green, the astronomer from the Royal Society, and Sydney Parkinson, natural history painter in the retinue of Joseph Banks, all eventually succumbed to the ‘flux’; and the disease ran through all other ranks including: the boatswain, the carpenter, the sailmaker, and a whole swathe of marines and seamen.

Cook completed his description of Batavia with the following text:

Batavia is certainly a place that Europeans need not covet to go to; but if necessity obliges them, they will do well to make their stay as short as possible, otherwise they will soon feel the effects of the unwholesome air of Batavia, which I firmly believe is the Death of more Europeans than any other place upon the Globe of the same extent. Such, at least, is my opinion of it, which is founded on facts. We came in here with as healthy a Ship’s Company as need go to Sea, and after a stay of not quite 3 months left it in condition of a Hospital Ship, besides the loss of 7 men; and yet all the Dutch Captains I had an opportunity to converse with said that we had been very lucky, and wondered that we had not lost half our people in that time.

What happened next is portrayed in a Google Earth presentation which plots Endeavour’s track after leaving Batavia. She was bound for England by way of the Cape of Good Hope. Not long after passing through the Straits of Sunda and while heading out into the Indian Ocean towards the trade winds, the men began to die. In the next 34 days there were 23 deaths. How very disheartening that must have been for the man who had kept scurvy at bay for 3 years and more.

Clearly, a bracing sea cruise is not the cure for dysentery. Cook felt that matters improved once they reached the trade winds, but the two screenshots above show the trail of death right across the Indian Ocean until Endeavour was to the south of Madagascar. Cook recorded the last deaths as follows:

Wednesday, 27th (February, 1771). Ditto Gales and Cloudy. In the A.M. died of the Flux Henry Jeffs, Emanuel Parreyra, and Peter Morgan, Seamen, the last came sick on board at Batavia, of which he never recover’d, and the other 2 had long been past all hopes of recovery, so that the death of these 3 men in one day did not in the least alarm us. On the contrary, we are in hopes that they will be the last that will fall a sacrifice to this fatal disorder, for such as are now ill of it are in a fair way of recovering.

To view the presentation described above, go to http://www.hazelhurst.net/Cook/ and select ‘Batavia to Cape of Good Hope’ in the menu system; then click on ‘Fevers and Fluxes’.

Copyright © Colin Hazlehurst, 2012

Captain Cook in Google Earth: Cape York to the Indonesian seas

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The channel next to the mainland was blocked by shoals and rocks (22Aug1770)

The channel next to the mainland was blocked by shoals and rocks (22Aug1770)

Even before reaching the western edge of Cape York it was clear that there was a passage to the south-west between the mainland and some islands. Cook instructed the smaller boats to sound the first channel between the mainland and the first island. They found this to be blocked by rocks and shoals, so Cook gave the signal for them to try the next channel. Here they found not less than 5 fathoms and they sailed through to anchor a few miles beyond the entrance to the channel.

Entrance to Endeavour Strait (22Aug1770)

Entrance to Endeavour Strait (22Aug1770)

Cook looked between the mainland to the south-west and Cape Cornwall on Prince of Wales Island:

Between these 2 points we could see  no land, so that we were in great hopes that we had at last found out a passage into the Indian seas; but in order to be better informed I landed with a party of men…upon the island which lies at the south-east point of the passage…after landing I went upon the highest hill which, however was of no great height, yet no less than twice or thrice the height of the ship’s mastheads; but I could see from it no land between south-west and west-south-west…

Possession Island

Possession Island

There is ambiguity on the internet concerning the island on which Cook landed. Look at this snapshot:

Will the real Possession Island please make itself known?

Will the real Possession Island please make itself known?

Wikipedia (places named by James Cook) goes for the island at the north-east end of the passage; surely that can’t be right. There are certainly some errors in Cook’s journal, but would he go to the island that was lower than the one next to it and further away from the direction he wanted to look?

The Google Earth Borders and Labels layer plumps for a patch of very low lying reef; certainly that is wrong.

I  chose for the tour the island that is actually at the south-east end of the entrance to Endeavour Strait and is actually high enough, at 70 metres, to be ‘no less than twice or thrice the height of the ship’s mastheads’.

There was no land to the south-west

There was no land to the south-west

Even from this vantage point Cook was still objective to the point of reticence:

Having satisfied myself of the great probability of a passage thro’ which I intended to go with the ship, and therefore may land no more upon this eastern coast of New Holland…I now once more hoisted English colours, and in the name of His Majesty King George The Third took possession of the whole eastern coast.

we fired 3 volleys of small arms which were answered by the like number from the ship

we fired 3 volleys of small arms which were answered by the like number from the ship

The following day, Endeavour sailed the length of Endeavour Strait and steered north-west for the small island which Cook named Booby Island (no prizes for guessing why). On entering Torres Strait, Cook noticed the swell from the south-west. This convinced him that there was no land in that direction for some distance and therefore:

…we had got to the westward extremity of Carpentaria, or the northern extremity of New Holland, and had now and open sea to the westward; which gave me no small satisfaction, not only because the danger and fatigues of the voyage was drawing near to an end, but by being able to prove that New Holland and New Guinea are two separate lands or islands, which until this day hath been a doubtful point among geographers.


Today, I added this leg of Cook’s exploration of the Australian coast to my Google Earth tour which presents his first voyage round the world. This leg completes my documentation of Cook’s exploration of Australia, from Point Hicks in the south to Cape York in the north.

Along the way Endeavour made an extended visit to Botany Bay, ran aground on a reef, was repaired in Endeavour river, passed outside the reef through Cook’s passage near Lizard Island, only to be nearly smashed to pieces on its outer edge a few days later. The ship was saved by being able to re-enter the reef system through Providential Channel.

Through perseverance and cautious navigation, Endeavour rounded Cape York less than a week later. Cook landed on Possession Island, from the summit of which he began to believe that he had found a passage between New Holland and New Guinea.

Copyright © Colin Hazlehurst, 2012
Images of Earth © Google and others

If you would like to follow Cook’s voyage, you will need to install the latest version of Google Earth on your computer; then go to the Captain Cook blog  and click on the links on the right-hand side of the page, under the ‘Google Earth’ heading. After the animation is loaded in Google Earth, you need to expand an entry in the Table of Contents. You will see a ‘Play’ icon which you double-click to start the animation. Don’t forget to enable your speakers to hear the spoken journal.

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