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Page 242
Ptolemy then proposes an ingenious combination of the Helikon principle with the eight-stringed kanon, enabling all the notes of the octave in any tuning to be sounded and, moreover, to be transposed wholesale to a higher pitch. It involves adjusting the distances between the strings so that they make the desired interval-ratios, as measured from a point out to the side, and stopping them by means of a long diagonal bridge pivoted at that point (Fig. 8.4). The stopped lengths, since they mark off equal triangles, stand in the same ratios to one another as the base lines, and are reduced proportionately as the bridge swings down.57
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FIG. 8.4. 
Ptolemy's adaptation of the Helikon
Rhythm
The aulete or citharist of the Archaic and Classical periods knew various nomoi appropriate to the accompaniment of different forms of song, dance, and recitation. Each nomos-name must have implied a particular rhythm or sequence of rhythms; and certain of the names either referred directly to rhythm or at a secondary stage came to serve as the names of rhythms.58 Thus there was a rudimen-
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5757 Harm. 2.2 p. 46.4ff.; Barker, GMW ii. 319-22.
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58Elegoi, Iamboi, Trochaic, Enoplian; cf. p. 216. Other rhythmic terms such as dactyl, anapaest, paeon, also probably originated as types of dance, etc.

 
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