In my chapter for manu kake I have cited Buck, which has given us his description of 'the annual Derby'. It is instructive to compare his matter-of-fact version with that in Hancock 3:

"On the south-western tip of Easter Island, at Orongo, up near the ragged edge of the Rano Kau crater, are four small holes very precisely pecked through the bedrock just beside a large Ahu. Since Orongo is known to have been an important ritual centre, these holes attracted the attention of the Norwegian Archaeological Expedition which visited the island in 1955-56. They were studied by Dr Edwin Ferdon. After making detailed observations at the solstices and the equinoxes he concluded: 'it can definitely be stated that the complex of four holes constituted a sun-observation device'.

As well as one Ahu, Orongo also formerly had one Moai, a unique specimen, carved out of basalt, that was removed to the British Museum in 1868. Perched on a headland with a precipitous drop to the ocean on one side and the gigantic, reed-filled crater of Rano Kau on the other, the main remaining feature of the site is a conglomeration of 54 squat oval houses with massively thick walls of horizontal stone slabs and domed corbel-vaulted ceilings.

The ritual that took place in this setting was the annual 'birdman' contest which was held each September - the month of the spring equinox in the southern hemisphere. The origins of this apparently bizarre ceremony are entirely unknown. Its centrepiece was a physical quest for the egg of a sooty tern and specifically for the first tern's egg of the season to be laid on the bird island of Moto-Nui which stands offshore just under a mile to the south-west of the Orongo headland.

The quest was undertaken on behalf of noble patrons by young champions called hopu manu ('servants of the bird') and officiated by the learned keepers of the inscribed Rongorongo tablets. On a signal from these scribes the hopu manu clambered down the cliffs of Orongo and paddled themselves out to the island on small conical reed floats called pora.

The first to return with a sooty tern's egg would then hand it triumphantly to his patron, who would forthwith be declared the 'Tangatu-Manu' - the sacred 'birdman'. He would be honoured as a king throughout the following year, during which he would shave his head and paint it bright red. At the same time a curious petroglyph of a long-beaked bird-headed man would be carved to represent him on the rocks of Orongo."

The 'servants of the bird', hopu manu, is a somewhat misleading translation. The main word is hopu which means 'to bathe':

Hopu

1. To wash oneself, to bathe, 2. Aid, helper, in the following expressions: hopu kupega, those who help the motuha o te hopu kupega in handling the fishing nets; hopu manu, those who served the tagata manu and, upon finding the first manutara egg, took it to Orongo. Vanaga.

Bath; to bathe, to cleanse (hoopu). Pau.: hopu, bath; to bathe. Ta.: hopu, to dive. Churchill.

Mq.: hopu, to embrace, to clasp about the body. Ma.: hopu, to catch, to seize. Churchill.

Tara (in manu tara) probably is related to our tara glyph:

The summary at tara:

 
The standard tara glyph type - without extra signs in form of 'toes', 'deformities' etc - stands at winter solstice and means 'point of return'.
 
The humpback whales coming up from the depths of the sea, surfacing for a moment, then to dive down again, offer a picture of what tara means - one movement (up) will not continue forever. After a while the reversed movement (down) will come.
 
Another picture is the pendulum, where one movement inevitably will come to full stop, then to reverse - a dynamic cyclical pattern.
 
Or like sailing in a canoe when there are moments where the movement must stop in order to tack and continue forward in the opposite direction.

Tara means 'thorn, spike, corner' etc. The new year appears - becomes visible - when the 'canoe' arrives at the southwest corner of the island. That is where Hotu Matua arrived.

Tara

1. Thorn: tara miro. 2. Spur: tara moa. 3. Corner; te tara o te hare, corner of house; tara o te ahu, corner of ahu. Vanaga.

(1. Dollar; moni tara, id.) 2. Thorn, spike, horn; taratara, prickly, rough, full of rocks. P Pau.: taratara, a ray, a beam; tare, a spine, a thorn. Mgv.: tara, spine, thorn, horn, crest, fishbone. Mq.: taá, spine, needle, thorn, sharp point, dart, harpoon; taa, the corner of a house, angle. Ta.: tara, spine, horn, spur, the corner of a house, angle. Sa.: tala, the round end of a house. Ma.: tara, the side wall of a house. 3. To announce, to proclaim, to promulgate, to call, to slander; tatara, to make a genealogy. P Pau.: fakatara, to enjoin. Mq.: taá, to cry, to call. 4. Mgv.: tara, a species of banana. Mq.: taa, a plant, a bird. Ma.: tara, a bird. 5. Ta.: tara, enchantment. Ma.: tara, an incantation. 6. Ta.: tara, to untie. Sa.: tala, id. Ha.: kala, id. Churchill

There he untied (tara) the two canoes from each other

... The two hulls were no longer kept lashed together (i.e., they were separated for the rest of the journey). Hotu called out to the canoe of the queen: 'Steer the canoe to the left side when you sail in. Teke will jump over on board (your) canoe to work his mana when you sail through the fishing grounds!'

Teke jumped on board the second canoe, (that) of the queen. The king's canoe sailed to the right, the queen's to the left. Honga worked his mana in the fishing grounds. (List of five fishing grounds that belong to Hotu and Honga.) Teke worked his mana in the fishing grounds to the left side. (List of nine fishing grounds that belong to Hotu and Teke.)

The men on board the royal canoe looked out from Varinga Te Toremo (the northeastern cape of the Poike peninsula). Then they saw the canoe of the queen, the canoe of Ava Rei Pua, as it reached Papa Te Kena (on the northern shore, east of Hanga Oteo). Honga came and gazed in the direction below (i.e., toward the west). He called out to the noteworthy ruler (? ariki motongi) Hotu: 'There is the canoe of the queen! It will be the first one to land!' ...

Hotu Matua went one way and his queen the other way. Together they encompassed the whole island. They were no longer united, they were untied. In between them the land appeared. It is the old myth about Ragi and Papa being separated to let in the light.

The geography of the island has Nga Kope Ririva located at the southwest corner. That is the direction of the setting sun, his way to the Underworld. When he returns again it is from the same direction. He does not appear at the horizon in the east. This seems to mean Nga Kope Ririva is referring to the yearly return of the sun king to the island, not to his return as a baby in the far away northeast.

Though, to break the shell of an egg the little one inside also needs a tara - an eggtoth:

Everything is interconnected in the old world of magic. There was no shortsighted analytic view of the world, images are wholes and should be perceived as such.

This ancient marvellous world view was basically the same all over the world. It was so important for survival that it accompanied man wherever he went. It was like the fire.

So far we have only had glimpses of it. We need to tie them together and therefore we must here also repeat a story about Raven:

... In the morning of the world, there was nothing but water. The Loon was calling, and the old man who at that time bore the Raven's name, Nangkilstlas, asked her why. 'The gods are homeless', the Loon replied. 'I'll see to it', said the old man, without moving from the fire in his house on the floor of the sea.

Then as the old man continued to lie by his fire, the Raven flew over the sea. The clouds broke. He flew upward, drove his beak into the sky and scrambled over the rim to the upper world. There he discovered a town, and in one of the houses a woman had just given birth. The Raven stole the skin and form of the newborn child. Then he began to cry for solid food, but he was offered only mother's milk. That night, he passed through the town stealing an eye from each inhabitant. Back in his foster parents' house, he roasted the eyes in the coals and ate them, laughing. Then he returned to his cradle, full and warm.

He had not seen the old woman watching him from the corner - the one who never slept and who never moved because she was stone from the waist down. Next morning, amid the wailing that engulfed the town, she told what she had seen. The one-eyed people of the sky dressed in their dancing clothes, paddled the child out to mid-heaven in their canoe and pitched him over the side. He turned round and round to the right as he fell from the sky back to the water. Still in his cradle, he floated on the sea. Then he bumped against something solid. 'Your illustrious grandfather asks you in', said a voice. The Raven saw nothing. He heard the same voice again, and then again, but still he saw nothing but water. Then he peered through the hole in his marten-skin blanket. Beside him was a grebe.

'Your illustrious grandfather asks you in', said the grebe and dived. Level with the waves beside him, the Raven discovered the top of a housepole made of stone. He untied himself from his cradle and climbed down the pole to the lowermost figure. Hala qaattsi ttakkin-gha, a voice said: 'Come inside, my grandson.' Behind the fire, at the rear of the house, was an old man white as a gull. 'I have something to lend you', said the old man. 'I have something to tell you as well. Dii hau dang iiji: I am you.'

Slender bluegreen things with wings were moving between the screens at the back of the house. Waa'asing dang iiji, said the old man again: 'That also is you.' The old man gave the Raven two small sticks, like gambling sticks, one black, one multicoloured. He gave him instructions to bite them apart in a certain way and told him to spit the pieces at one another on the surface of the sea. The Raven climbed back up the pole, where he promptly did things backwards, just to see if something interesting would occur, and the pieces bounced apart. It may well be some bits were lost. But when he gathered  what he could and tried again - and this time followed the instructions he had been given - the pieces stuck and rumpled and grew to become the mainland and Haida Gwaii ...

These gambling sticks which had to be bit apart, then to sail on the surface of the sea, resemble (not by accident) the two parts of the double-canoe of Hotu Matua. The black stick is the stick of night and the multicoloured one is the stick of day.

But for the Haida Gwaii the story was told from the other direction: Land grew because the pieces stuck together, tied instead of untied. I think the opposite Easter Island version is an adaptation to local 'geography'.

In ancient Egypt the uniting of the two parts of 'land' was illustrated thus:

Wilkinson says that the coloured sign means 'uniting', sema. On top is Ramses III and he as king is uniting upper and lower Egypt. Horus (left) should be the day (the upper part) and Seth the night, the lower part close to the sea.

The word sema is related to hemi (in hemisphere), to demi (in demigod), to semi (in semicircle), and also to words with the first vowel as a instead of e:

"... Skr. sāmi, and OS. sām-, OHG. sāmi-, OE. sām- (as in sambærned half-burnt, samcwic 'half-alive', half-dead, samsoden partly cooked ..." (English Etymology)