A great source of information about Rongorongo is the web site www.rongorongo.org
Rapanui "signatures" (from Fischer).
"Dans toutes les cases on trouve des tablettes de bois ou des bâtons couverts de plusieurs espèces de caractères hiéroglyphiques: ce sont des figures d'animaux inconnues dans l'île, que les indigènes tracent au moyen de pierres tranchantes. Chaque figure a son nom; mais le peu de cas qu'ils font de ces tablettes m'incline à penser que ces caractères, restes d'une écriture primitive, sont pour eux maintenant un usage qu'ils conservent sans en chercher le sens."
Here an example of Jaussen's catalog (see http://www.netaxs.com/~trance/frame.html
According to Thomson, Ure Vaeiko sang a procreation hymn Atua Mata-Riri when shown a picture of the Small Washington Tablet (though Fischer disagrees); and another text, Apai, when shown a picture of table Keiti.
The text of Atua Mata-Riri is apparently a creation myth of the form "X mated with Y and produced Z".
(Guy argues Atua Mata Riri might just be a "spelling bee")
(Fischer, p 458: "Thomson (1981) or his editor at the Smithsonian, mistakenly called [this tablet] `Atua Matariri' after the first name of Ure Va'e Iko's procreation chant that was sung to the photograph of one of Bishop Jaussen's tablets, not to this one")
For some examples see: http://compling.ai.uiuc.edu/rws/ror/.
Prayers to the Gods. Institute of Archaeology, University of California, Los Angeles, Monumenta Archaeologica 17. Page 71.
The symbol on line 3 seems to correspond to two symbols on lines 4 and 6: it seems to consist of a fusion of the two glyphs representing the bird-headed figure, and the lens-shaped glyph with the two raised arms. It also seems as if the fused glyph is to be read upwords (i.e. upwards catenation in the terminology of Sproat 2000). (Jacques Guy. 1982. "Fused glyphs in the Easter Island script." Journal of the Polynesian Society. 91:445-447)
(From: Andrew Robinson, 1995. The Story of Writing. London, Thames and Hudson. page 147)
Thus:
is supposed to be
rangi "send, visit", decomposed as: MOTION (lefthand
symbol of a running figure), with rangi, meaning "sky", but
used here for its phonetic value.
Barthel provided the first catalog of the tablets and a catalog of the glyphset as well as a corpus based on etchings. But it is claimed that about 7-10% of Barthel's tracings are errorful. On top of this, his coding system (as any coding system) is a judgment call, and the system is "lossy".
Barthel's coding system is based, somewhat algorithmically, on the form of the characters. See: http://www.rongorongo.org/corpus/codes.html. The Cercle d'Études sur l'Île de Pâques et la Polyné'sie has extended Barthel's system.
There has also been dissatisfaction with his glyphset, with many people arguing that he made too many distinctions.
The main problem with Barthel's approach is that he relied on the assumption that Metoro's chantings were a key to the decipherment.
The Santiago staff is the only text where there are apparent text
divisions. Fischer analyzes the groups on the staff as representing
the type of procreational text sung by Ure Va'e Iko in his Atua
Mata Riri. Thus he proposes that
be translated as "Te manu mau
ki 'ai ki roto ki te ika, [ka pû] te ra'â", "all the birds
copulated with the fish and there issued forth the sun". He argues
that the grabbing hand on the bird represents the word mau
'all' (ma'u = 'grab' in Old Rapanui, hence a rebus).
Crucial in Fischer's decipherment is the presence of the phallus-like appendage apparently representing "copulate". But he then goes on to suggest that a number of other phallus-less texts also represent procreation chants. (There is a phallus-less sequence BIRD-FISH-SUN on the tablet Échancrée.)
Fischer has been roundly criticized by Jacques Guy. See, http://www.rongorongo.org/rosetta/i2.html and elsewhere. Indeed there are a number of problems with Fischer's analysis:
Pozdniakov, Konstantin. 1996. "Les bases du déchiffrement de l'écriture de l'île de Pâques". Journal de la Societé des Océanistes, 103(2), pages, 289--303.
There is just one teensy little problem with these analyses: neither Macri nor Pozdniakov have published their decomposition, so until they do, there is little reason why one should accept their claims to have found a decomposition.
Pozdniakov does a little better than Macri. He at least does some statistical analysis that purports to show that the statistical distribution of his decomposed syllable set correlates with the distribution of syllables in the Rapanui language, for example, using the text Apai as the source of the linguistic syllable distribution. This results in a plot like the following, where the two curves are claimed to be "pratiquement identiques".
But Pozdniakov would appear to have merely re-discovered Zipf's law (well, not quite since the populations of syllables are too small for the curves to be truly Zipfian). Using this argument I can show that the letters (upper and lower case, including punctuation) in the first 12,000 words of the English version of Genesis encode Rapanui.
In any case, if Pozdniakov is right he ought to be able to take his reduced glyph set, use the frequencies to match them one-for-one with the syllables, and then proceed to translate. The fact that this hasn't happened would seem to suggest that things cannot be so simple.
The ethnographer Alfred Métraux proposed that Rongorongo is a mnemonic device rather than a way of representing the Rapanui language directly, though he later backed away from that belief, due to Barthel's work. (But then Barthel's decipherment attempts were never successful.)
One possible model is the script of the Naxi (Sino-Tibetan), a minority people of China.
Naxi Dongba texts have only recently been translated, in this case with the help of living Dongba experts. For the most part the script does not represent language in the normal sense that a writing system does: rather, "several characters may tell a complete story, and sometimes, a character in one script might not have the same meaning in another script." (see http://fpeng.peopledaily.com.cn/200001/24/eng20000124R121.html). In other words, a significant function of Dongba script is to provide mnemonic cues to texts that the reader knows.
If Rongorongo is like Dongba, then the hopes of ever deciphering significant portions of it are slim indeed. Previous attempts to decipher Dongba without the help of native experts failed.