Harmonium

HARMONIUM, a wind, keyboard instrument, otherwise a small organ without pipes, furnished with free reeds. Both the harmonium and its later development, the American organ, are known as free-reed instruments, the musical tones being produced by tongues of brass, technically termed "vibrators." The vibrator is fixed over an oblong, rectangular frame, through which it swings freely backwards and forwards like a pendulum while vibrating, whereas the beating reeds (similar to those of the clarinet family), used in church organs, cover the entire orifice, beating against the sides at each vibration. A reed or vibrator, set in periodic motion by impact of a current of air, produces a corresponding succession of air puffs, the rapidity of which determines the pitch of the musical note. There is an essential difference between the har monium and the American organ in the direction of this current; in the former the wind apparatus forces the current upwards, and in the latter sucks it downwards, whence it becomes desirable to separate in description these varieties of free-reed instruments.

Harmonium.

This has a keyboard of five octaves compass when complete, and a simple action controlling the valves, etc. The necessary pressure of wind is generated by bellows worked by the feet of the performer upon foot-boards or treadles. The air is thus forced up the wind-trunks into an air-chamber called the wind-chest, the pressure of it being equalized by a reservoir, which receives the excess of wind through an aperture, and permits escape, when above a certain pressure, by a discharge valve or pallet. The aperture admitting air to the reservoir may be closed by a drawstop named "expression." The air being thus cut off, the performer depends for his supply entirely upon the manage ment of the bellows worked by the treadles, whereby he regulates the compression of the wind. The character of the resulting tone is then entirely changed from a mechanical response to the player's touch to an expressive one, varying in correspondence with the increase or diminution of sound through the greater or less pres sure of wind to which the reeds may be submitted. The drawstops bearing the names cif the different registers in imitation of the organ, admit, when drawn, the wind from the wind-chest to the corresponding reed compartments, shutting them off when closed.

American Organ.

This acts by wind exhaustion. A vacuum is practically created in the air-chamber by the exhausting power of the footboards, and a current of air thus drawn downwards passes through any reeds that are left open, setting them in vibra tion. Valves in the board above the air-chamber give communica tion to reeds made more slender than those of the harmonium and more or less bent, while the frames in which they are fixed are also differently shaped, being hollowed rather in spoon fashion.

The channels, • the resonators above the reeds, are not varied in size or shape as in the harmo nium ; they exactly correspond with the reeds, and are collec tively known as the "tubeboard." The American organ has a softer tone than the harmonium. The "automatic swell" in the instru ments of Mason and Hamlin (of Boston, U.S.A.), is a contrivance which assists expression. Another very clever improvement intro duced by these makers, who were the originators of the instru ment itself, is the "vox humana," effected by a fan, made to re volve rapidly by a wind pressure; its rotation, disturbing the air near the reeds, causes interferences of vibration that produce a tremulous effect, not unlike the beatings heard from combined voices, whence the name.

History.

The start in the instrument's invention was due to Prof. Christian Gottlieb Kratzenstein of Copenhagen, who having had the opportunity of examining a Chinese cheng sent to his native city, invented about 1779, a small pneumatic organ fitted with free reeds which appears to have been the first instrument of its kind.

During the first half of the 19th century numerous efforts in France and Germany, and subsequently in England, were made to produce new keyboard instruments with free reeds, the most notable of these being the physharmonica of Anton Hackel, in vented in Vienna in 1818, which, improved and enlarged, has re tained its hold on the German people. The modern physharmonica is a harmonium without stops or percussion action; it does not theref ore speak readily or clearly. It has a range of five or six octaves. Other instruments of similar type are the French melo phone and the English seraphine, a keyboard harmonica with bellows but no channels for the tongues, for which a patent was granted to Myers and Storer in 1839 ; the aeoline or aelodicon of Eschenbach ; the melodicon of Dietz; the melodica of Rieffelson; the apollonicon; the new cheng of Reichstein; the terpodion of Buschmann, etc. But none of these has survived.