The frame of a lyre consists of a hollow body or sound-chest. From this sound-chest are raised two arms, which are sometimes hollow, and are bent both outward and forward. They are connected near the top by a crossbar or yoke . Another crossbar, fixed on the sound-chest, forms the bridge which transmits the vibrations of the strings. The deepest note was the farthest from the player; but, as the strings did not differ much in length, more weight may have been gained for the deeper notes by thicker strings, as in the violin and similar modern instruments, or they were turned with slacker tension. The strings were of gut. They were stretched between the yoke and bridge, or to a tailpiece below the bridge. There were two ways of tuning: one was to fasten the strings to pegs which might be turned; the other was to change the place of the string upon the crossbar; probably both expedients were simultaneously employed.
The number of strings varied at different epochs, and possibly in different localities - four, seven and ten having been favourite numbers. They were used without a finger-board, no Greek description or representation having ever been met with that can be construed as referring to one. Nor was a bow possible, the flat sound-board being an insuperable impediment. The plectrum, however, was in constant use. It was held in the right hand to set the upper strings in vibration; at other times it hung from the lyre by a ribbon. The fingers of the left hand touched the lower strings.
There is no evidence as to what the stringing of the Greek lyre was in the heroic age. Plutarch says that Olympus and Terpander used but three strings to accompany their recitation. As the four strings led to seven and eight by doubling the tetrachord, so the trichord is connected with the hexachord or six-stringed lyre depicted on so many archaic Greek vases. We cannot insist on the accuracy of this representation, the vase painters being little mindful of the complete expression of details; yet we may suppose their tendency would be rather to imitate than to invent a number. It was their constant practice to represent the strings as being damped by the fingers of the left hand of the player, after having been struck by the plectrum which he held in the right hand. Before Greek civilization had assumed its historic form, there was likely to have been great freedom and independence of different localities in the matter of lyre stringing, which is corroborated by the antique use of the chromatic (half-tone) and enharmonic (quarter-tone) tunings pointing to an early exuberance, and perhaps also to an Asiatic bias towards refinements of intonation.
Edited and wikified from a 1911 encyclopedia