page_title: Decipherment of rongorongo
section_title: Barthel
hierarchical_section_title: Decipherment of rongorongo / Barthel
caption_attribution_description: The calendar on rongorongo tablet C Mamari
context_page_description: There have been numerous attempts to decipher the rongorongo script of Easter Island since its discovery in the late nineteenth century. As with most undeciphered scripts, many of the proposals have been fanciful. Apart from a portion of one tablet which has been shown to deal with a lunar calendar, none of the texts are understood, and even the calendar cannot actually be read. It is not known if rongorongo directly represents the Rapa Nui language – that is, if it is a true writing system – and oral accounts report that experts in one category of tablet were unable to read other tablets, suggesting either that rongorongo is not a unified system, or that it is proto-writing that requires the reader to already know the text.
context_section_description: German ethnologist Thomas Barthel, who first published the rongorongo corpus, identified three lines on the recto (side a) of tablet C, also known as Mamari, as a lunar calendar. Guy proposed that it was more precisely an astronomical rule for whether one or two intercalary nights should be inserted into the 28-night Rapanui month to keep it in sync with the phases of the moon, and if one night, whether this should come before or after the full moon. Berthin and Berthin propose that it is the text which follows the identified calendar that shows where the intercalary nights should appear. The Mamari calendar is the only example of rongorongo whose function is currently accepted as being understood, though it cannot actually be read.
  In Guy's interpretation, the core of the calendar is a series of 29 left-side crescents ("☾", colored red on the photo of the table at right) on either side of the full moon, , a pictogram of te nuahine kā ꞌumu ꞌa rangi kotekote 'the old woman lighting an earth oven in the kotekote sky'—the Man in the Moon of Oceanic mythology. These correspond to the 28 basic and two intercalary nights of the old Rapa Nui lunar calendar.
  These thirty nights, starting with the new moon, are divided into eight groups by a "heralding sequence" of four glyphs (above, and colored purple on the tablet at right) which ends in the pictogram of a fish on a line (yellow). The heralding sequences each contain two right-side lunar crescents ("☽"). In all four heralding sequences preceding the full moon the fish is head up; in all four following it the fish is head down, suggesting the waxing and waning of the moon. The way the crescents are grouped together reflects the patterns of names in the old calendar. The two ☾ crescents at the end of the calendar, introduced with an expanded heralding sequence, represent the two intercalary nights held in reserve. The eleventh crescent, with the bulge, is where one of those nights is found in Thomson's and Métraux's records.
  Guy notes that the further the Moon is from the Earth in its eccentric orbit, the slower it moves, and the more likely the need to resort to an intercalary night to keep the calendar in sync with its phases. He hypothesizes that the "heralding sequences" are instructions to observe the apparent diameter of the Moon, and that the half-size superscripted crescents (orange) preceding the sixth night before and sixth night after the full moon represent the small apparent diameter at apogee which triggers intercalation. (The first small crescent corresponds to the position of hotu in Thomson and Métraux.)
  Seven of the calendrical crescents (red) are accompanied by other glyphs (green). Guy suggests syllabic readings for some of these, based on possible rebuses and correspondences with the names of the nights in the old calendar. The two sequences of six and five nights without such accompanying glyphs (beginning of line 7, and transition of lines 7–8) correspond to the two groups of six and five numbered kokore nights, which do not have individual names.
caption: The Mamari calendar starts midway through recto line 6 (bottom center, upside down) and continues to the start of line 9 (top left). Two glyphs are not visible at the start of 7; these complete the heralding sequence at the end of line 6 (ellipsis). Multiple beaded variants of double and triple lozenges (glyph 2 glyph 2 abacus-like "accounting sets") follow the identified calendar.
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