For the sake of completeness, it is necessary to speak briefly about some inventions made in con nection with the pianoforte. There is a device for increasing the volume of tone. This is the (voila), attachment, an arrangement by means of which a current of air is directed against the strings, reinforcing the vibrations and thus caus ing a eonsideralde increase in the volume and duration of the tone. In 1891 Dr. Eisenmann, of Berlin, invented the electric piano. Besides the ordinary hammer-action this instrument has an electro-magnet attached to each string. By press ing down the keys an electric circuit is closed, and the action of the electromagnets causes a steady vibration of the strings. When the elec tric action is employed alone. the tone of the piano closely resembles that of the' stringed in struments. By means of a special pedal any tone or ehord can be sustained at will even after the fingers have left the keys. The electric action or the hammer-action may be employed each sep arately, or both may be combined. Many in genious devices have been invented by which the piano can he played automatically, the most suc cessful of which is perhaps the pianola. The great advantage of this invention is the control which the player can exercise over expressive in terpretation by means of fine dynamic shading and modifications of tempo. But, like all me chanical contrivances, it has its shortcomings, as the inability to bring out a melody in the mid dle voices. The idea of dumb keyboards is quite old. The digitorium or dumb piano is a port able box having five keys supported on springs.
The use of it has always been strongly con demned by good musicians. In 1883 Mr. Virgil of New York invented the Virgil practice charier, which is now extensively used and has several points of excellence. It has a complete keyboard. Each key when pressed down gives an audible click. There is a mechanism by means of which the player is enabled to cause a second click upon the release of a key. This is of great advantage in the practice of a legato touch. The performer need only see to it that the two clicks, the one produced by the release of a key, the other by the depression of the next key, coincide exactly. By means of a mechanical adjustment the action can be regulated at will from the very lightest pianoforte touch ,(2 ounces) up to 20 ounces. If used with judgment this is an excellent device for acquiring strength of the fingers. For exer cises of a purely technical nature, the clavier is a valuable help. Some standard works dealing with the history of the pianoforte are: Rimbault, History of the Pianoforte (London, 1860) ; Paul, Geschichte des Klaviers (Leipzig, 1868) ; Gon tershausen, Der Klavierbau (Frankfort, 1870) ; Ponsicchi, Il pianoforte, sua origine e sviluppn (Florence, 1876) ; Bliithner and Gretsehel, Lehr buch des Pianofortebaues (Weimar, 1886) ; Spill ane, History of the American Pianoforte (New York, 1890) ; Hipkins, The Pianoforte (London, 1896) ; Die, A History of the Pianoforte and Pianoforte Players, trans. from the German (London, 1899). See HARPSICHORD; MONOCHORD: PANTALEON; SPINET; VIRGINAL.