A Dictionary of Music and Musicians/Æolian Harp
ÆOLIAN HARP. (Fr. La Harpe Æolienne; Ital. Arpa d' Eolo; Ger. Æolsharfe Windharfe.) The name is from Aeolus the god of the wind. The instrument, of which the inventor is unknown, would appear to owe its origin to the monochord, a string stretched upon two bridges over a soundboard. The string happening to be at a low tension and exposed to a current of air would divide into various aliquot parts according to the varying strength of the current, and thus give the harmonics or overtones we hear in the music of this instrument. Had the principle of the Æolian harp never been discovered, we should in these days of telegraphy have found it out, as it is of frequent occurrence to hear musical sounds from telegraph wires which become audible through the posts which elevate the wires, and assume the function of soundboards. Once recognised on a monochord, it would be a simple process to increase the number of strings, which, tuned in unison, would be differently affected in relation to the current of air by position, and thus give different vibrating segments, forming consonant or dissonant chords as the pressure of wind might determine. That musical sounds could be produced by unaided wind has been long known in the East. According to tradition King David's harp (kinnor) sounded at midnight when suspended over his couch in the north wind; and in an old Hindu poem, quoted by Sir William Jones, the vina, or lute of the country is said to have produced tones, proceeding by musical intervals, by the impulse of the breeze. In the present day the Chinese have kites with vibrating strings, and the Malays have a curious Æolian instrument, a rough bamboo cane of considerable height, perforated with holes and stuck in the ground. This is entirely a wind contrivance, but they have another of split bamboo for strings. (C. Engel, 'Musical Instruments,' 1874, p. 200.) St. Dunstan of Canterbury is said to have hung his harp so that the wind might pass through the strings, causing them to sound, and to have been accused of sorcery in consequence. This was in the 10th century. It was not until the 17th we meet with the Æolian harp itself. Kircher (1602-1680) first wrote about it. He speaks of it in his 'Musurgia Universalis' as being a new instrument and easy to construct, and as being the admiration of every one. He describes the sounds as not resembling those of a stringed or of a wind instrument, but partaking of the qualities of both. This is quite true, and applies to any stretched string the sound of which is made continuous by any other agency than that of a bow, and not dying away as we usually hear the tones of pianofortes, harps, and guitars. Thomson, in the 'Castle of Indolence,' in well-known lines, describes the Æolian harp, but except one phrase, 'such sweet, such sad, such solemn airs divine,' misses the elegiac note that distinguishes the instrument. Matthew Young, bishop of Clonfert, in his 'Enquiry into the Principal Phenomena of Sounds and Musical Strings' (1784), gives full particulars of it, and offers a theory of its generation of sound. It also gained attention in Germany about the same time, through a description of it in the 'Gottingen Pocket Calendar' for 1792. H. C. Koch, a German, appears to have bestowed the most attention upon the effects obtainable by varying the construction and stringing of the Æolian harp; but it is of little importance whether the tone be a little louder or a little softer, the impression to be derived from the instrument is as attainable from one of simple build as from double harps, or from one with weighted (spun) strings added.
An Æolian harp is usually about three feet long, five inches broad, and three inches deep; of pine wood, with beech ends for insertion of the tuning- and hitch-pins, and with two narrow bridges of hard wood over which a dozen catgut strings are stretched. These are tuned in the most exact unison possible, or the beats caused by their difference would be disagreeable. The direction sometimes attached to tune by intervals of fourths and fifths is only misleading. The tension should be low; in other words, the strings be rather slack, the fundamental note not being noticeable when the instrument sounds. There are usually two soundholes in the soundboard. The ends are raised above the strings about an inch, and support another pine board, between which and the soundboard the draught of air is directed. To hear the Æolian harp it should be placed across a window sufficiently opened to admit of its introduction, and situated obliquely to the direction of the wind. The evening time is the best, as the feelings are then more attuned to the chords we are to listen to. The modifications of tone, increasing and decreasing in a manner inimitable by voices or instruments, are perfectly enchanting. An instrument producing chords by the wind alone, without our interference, stimulates the fancy, and is in itself an attractive phenomenon. The sounds are so pure and perfectly in tune, that no tuning we might accomplish could rival it. For we have here not tempered intervals but the natural tones of the strings, the half or octave, the third or interval of the twelfth, and so on, in an arithmetical progression, up to the sixth division, the whole vibrating length being taken as the first—we are listening to full and perfect harmony. But the next, the seventh, still in consonance with the lowest note, in effect not unlike the dull sad minor sixth, but still more mournful, is to our ears transcendental, as our musical system does not know it: and it would be too much out of tune with other intervals consonant to the key-note for admission to our scales. We are impressed with it as by a wail—in the words of Coleridge a 'sweet upbraiding,' ('The Æolian Harp,' Poems, i. 190)—to be followed as the wind-pressure increases by more and more angry notes as we mount to those dissonances in the next higher octave, especially the eleventh and thirteenth overtones that alternate and seem to shriek and howl until the abating gust of wind suffers the lower beautiful harmonies to predominate again. The mind finds in this return a choral echo as of some devotional antiphon, at least this has been the writer's experience, and not the mingling of violins, flutes, harps, and chromatic sequences by which some have described it. The Æolian harp is nature's music; man's music is au art, implying selection. He chooses intervals to construct his scales with, and avoids ratios that do not coincide with his instinctive feeling or intention.