There is a singular similarity to be observed between this heel-tapping and the complicated drum-tapping of the African negroes of certain tribes. In his book "Afro-American Folksongs" H. E. Krehbiel thus describes the musical accompaniment of the dances in the Dahoman Village at the World's Columbian Exposition in Chicago: "These dances were accompanied by choral song and the rhythmical and harmonious beating of drums and bells, the song being in unison. The harmony was a tonic major triad broken up rhythmically in a most intricate and amazingly ingenious manner. The instruments were tuned with excellent justness. The fundamental tone came from a drum made of a hollowed log about three feet long with a single head, played by one who seemed to be the leader of the band, though there was no giving of signals. This drum was beaten with the palms of the hands. A variety of smaller drums, some with one, some with two heads, were beaten variously with sticks and fingers. The bells, four in number, were of iron and were held mouth upward and struck with sticks. The players showed the most remarkable rhythmical sense and skill that ever came under my notice. Berlioz in his supremest effort with his army of drummers produced nothing to compare in artistic interest with the harmonious drumming of these savages. The fundamental effect was a combination of double and triple time, the former kept by the singers, the latter by the drummers, but it is impossible to convey the idea of the wealth of detail achieved by the drummers by means of exchange of the rhythms, syncopation of both simultaneously, and dynamic devices. Only by making a score of the music could this have been done. I attempted to make such a score by enlisting the help of the late John C. Filmore, experienced in Indian music, but we were thwarted by the players who, evidently divining our purpose when we took out our notebooks, mischievously changed their manner of playing as soon as we touched pencil to paper."