ACTION (Fr. Le Mécaniqne; Ital. Mecanica; Ger. Mechanismus, Mechanik), the mechanical contrivance by means of which the impulse of the player's finger is transmitted to the strings of a pianoforte, to the metal tongue (free reed) of a harmonium, or by the finger or foot to the column of air in an organ-pipe. In the harp the action, governed by the player's foot upon the pedals, effects a change of key of a semitone or whole tone at will. In the pianoforte the action assumes special importance from the capability this instrument has to express gradations of tone; and as the player's performance can never be quite consciously controlled—more or less of it being automatic—we are, through the faithful correspondence of the action with the touch, placed in direct relation with the very individuality of the player. It is this blending of conscious and unconscious expression of which the pianoforte action is the medium that produces upon us the artistic impression. There have been important variations in the construction of pianoforte actions that have had even geographical definition, as the English, the German action, or have been named from structural difference, as the grasshopper, the check, the repetition action. In the organ and harmonium, as in the old harpsichord and spinet, the action bears a less important part, since the degree of loudness or softness of tone in those instruments is not affected by the touch. For history and description of the different actions see Clavichord, Harmonium, Harp, Harpsichord, Organ, and Pianoforte.