To beat the Allegro in four gives it precision but takes away from the light and graceful airiness of the figure by giving undue prominence to the third beat. In any 4/4 or 4/8 gesture the third beat is apt to get almost as strong an accent as the first.
The Allegro Vivace of Mozart’s “Jupiter Symphony” is also taken alla breve instead of in four beats as marked. A number of present day conductors are taking the March in the “Pathetique Symphony” of Tschaikowski in alla breve time with very marked success.
On the other hand there are types of compositions that need the greater energizing power of the four beats. Percy Grainger’s “Molly on the Shore”[2] is a good example of one of these. He requests the conductor to keep four equally accented beats hammering away throughout the whole piece.
[2] Copyright 1911, by G. Schirmer, Inc. N. Y.
In conducting fast moving tempos one-in-a-bar, the conductor will soon notice the individual bars grouping themselves together in phrases and periods, and it is most helpful to the musicians if some slight indication of the groupings be given in conducting. In fast one-in-a-bar movements four single measures often become one large measure of four beats, and if the beginning and termination of this measure group is indicated by a slightly larger beat, the musical composition becomes more intelligible to the player and listener.
Thus the beginning of Beethoven’s Fifth Symphony