Page 90 - J. C. Turner "History and Science of Knots"
P. 90

The Peruvian  Quipu                     79

       of  both kinds were found on ancient specimens.  Those of  the first kind  were
       found only in the North of  the country; those of  the second kind  only in the
       South.  Hence it was probably  a matter of  tradition which  method was used,
       and every quipu keeper used only one of  them.
           There was no special sign to indicate an 'empty'  digit, like our 0 in  101
       for example.  The positions were  carefully  aligned from cord to cord, so that
       a  space without  knots  could  be  associated  unambiguously with  its position.
       There remains ambiguity in the cases of small quipus where a position is empty
       on every pendant cord. In these cases, which probably occurred rather seldom,
       the length of  the spaces might have been considered.  Fig. 6 shows a schematic
       example.
       The Number Zero
       Although  there  was  no  special sign  for  zero,  we  can  assume  that  the  Incas
       had  the  concept  of  nothingness  in  their  number  system.  They  represented
       zero by  a  cord without  knots.  We  can conclude this because  the colour code
       allowed meaningless cords to be omitted, as the following example illustrates.
       Imagine  a  quipu designed  for recording  the number  of  sandals owned by  the
       people of  a village.  Each pendant  group represents a family, with the number
       of  the men's  sandals  on  the first  cord, the women's  on  the second  and  the
       children's  on the third.  The second categorization can be reinforced  by  using
       colours,  for  example  green  cords  for  men,  yellow  cords  for  women  and  red
       cords for children.  If  a family does not have any children, the red cord can be
       omitted without ambiguity.  A red cord without knots would mean that there
       are children in the family, but they do not own any sandals.
           As  cords  without  knots,  and  also  repeated  colour  patterns  with  single
       cords omitted, occur frequently on ancient quipus, we  have to assume that it
       was on purpose;  and this is the most likely explanation.  We  also know  that
       another ancient American  culture, the Mayas, had the number  zero, and it is
       possible  that the Incas took it over from them.


       The Contents
       This section deals with  the types  of  information  that Incas stored  on  their
       quipus.  These include statistical data and astronomical observations; possibly
       non-numerical  data were also recorded, using number codes.
       Statistics
        The chroniclers describe the use of  quipus for recording  statistical numbers.
       There  was  a  regular  census,  as  we  know  from  Garcilasso.  Every  year  the
       population  figures were recorded, divided  into provinces, villages, sex, age in
       decade intervals, and groups of unmarried, married, and widowers. There were
       also regular  statistical reports on resources like agricultural produce, herds of
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