A Dictionary of Music and Musicians/Beat
BEAT. The movement of the hand or baton by which the rhythm of a piece of music is indicated, and by which a conductor ensures perfect agreement in tempo and accent on the part of the orchestra or chorus; also, by analogy, the different divisions of a bar or measure with respect to their relative accent.
Among the ancients the ordinary method of beating time was by striking the foot upon the ground. The person who exercised this function, corresponding to our modern conductor, was called by the Greeks Coryphaeus (principal), and by the Romans Pedarius or Pedicularius, from the custom of employing the foot to beat with, and it was usual for him to wear sandals of wood or metal, called pedicula or scabella, in order by their percussion to render the rhythm more evident. Sometimes the measure was marked by clapping the hands—in which case the timebeater was called Manuductor; and sometimes by the striking together of oyster-shells, bones, etc.
To our ears this incessant and noisy percussion would be unendurable, and a modern conductor would be severely criticised who could not keep his performers in tune by the noiseless movements of his baton; nevertheless, the improvement is of comparatively recent date, for we find Rousseau in 1768 complaining that the listener at the Paris opera should be 'shocked by the continual and disagreeable noise made by him who beats the measure.'
The method of beating now commonly in use in England, France, and Germany is as follows:—the first note of each bar (which has always the strongest accent) is indicated by a downward movement of the hand or baton, and this part of the bar is therefore usually known as the 'down-beat'; in triple time this is followed by two unaccented beats, which are shown by a movement first to the right and then upwards, unless in scherzos or other movements in rapid time, where it is usual to give merely a down beat at the beginning of the bar. In common time there may be either one or three non-accents, in the first case the simple up-beat suffices, in the latter the beats following the down-beat are to the left, to the right, and then upwards. In all cases the movement immediately preceding the down-beat is an up-beat.
In beating compound time (that is, time in which each beat is made up of three parts) it is customary to give each beat three times in succession, thus in 12-8 time there would be three down, three left, three right, and three up-beats, except in rapid tempo, when the ordinary number of beats will suffice, one beat being equivalent to three notes.
In the greater part of Italy a somewhat different method ot beating is adopted, there being no beats to the right or left; when therefore there are more than two beats in a bar, two down-beats are given in succession, followed in triple time by one and in common time by two up-beats.
In theoretical works, the down-beat or accent, and the up-beat or non-accent, are usually spoken of by their Greek names of thesis and arsis.