Music for dances is furnished by an orchestra consisting of four men, three with copper gongs (_gangsas_), and one with a drum. The gongs are tambourine shape, with sides about an inch and a half high. They are placed against the thighs of the players who kneel on the ground, and are beaten with a stick and the palm of the hand or by the hands alone. [249] They doubtless came into this region through trade, but at a time so remote that their origin is now credited to the spirits. The drum (_tambor_) is made of a short section of a tree hollowed out. The ends are covered with cow's hide or pig's skin. CHAPTER XII MUSIC _Introduction_.--That the songs might be delivered as nearly as possible at the same pitch which the singers used when making the records, investigation was made as to the usual speed used by manufacturers while recording. It was found to be 160 revolutions per minute. Accordingly the phonograph was carefully set at this speed during transcription. In determining the keys in which to transcribe the various songs, the pitch-pipe used was that of the "International," which was adopted at the Vienna Congress in Nov. 1887. This congress established c2 = 522 double vibrations per second. All the records proved to be a shade flat by this standard, but were found to be almost exactly in accord with an instrument of fixed pitch, which in turn was found to be approximately eleven beats at variance with the pitch-pipe on c2. Assuming that the recording and transcribing speeds of the machines were the same, this would place the original singing almost exactly in accord with the old "philosophical standard of pitch" which places c2 at 512 double vibrations per second. Though the singing was not always in perfect accord with the notes set down in transcriptions, with the exception of those very marked departures especially indicated in the music, the variations were so slight that, so far as true intonation goes, the performances were fully up to the standard of those of the average natural singer. Special ear tubes were used while transcribing the records, and resort made to a special device wherewith any order of whole, or even part measures could be consecutively played. Thus it was possible to closely compare parts which were similar in either words or music. In some of the records two or more voices can be distinguished singing in unison. Such unisons are shown in the transcription by single notes. No attempt has been made to indicate the several voices. But when such single notes are shown accompanied by the word "solo," it is to be understood that all of the performers have dropped out but one, probably the leader. When the voices split up into parts, it is so notated in the music.