Chapter XLIX: æolian Harps, and How to Make Them

The simplest pattern of Æolian harp is that which fits into any ordinary window frame. A box of thin straight-grained, well-planed deal is glued together, having a length equal to that of the width of the window for which it is destined, a depth of four or five inches, and a breadth of five or six inches. The wood of which it is made is carefully planed on both sides, and is not over an eighth of an inch in thickness, and the joints are as true and clean as it is possible to make them. The more carefully this box is made the better will be the tone of the instrument.

The bridges in all Æolian harps are of some hard wood, such as oak, box, or elm, and are glued on to the face of the sounding-case. They are about half an inch high and a quarter of an inch thick. The strings are of catgut tightened by pegs screwed into the edges of the case, which are occasionally strengthened for the purpose by a thin fillet of beech. The strings are tuned in unison. Three inches above them is placed a thin board, supported on four pegs, one at each corner of the case. The harp is rested on the bottom of the window frame, and the sash is brought down on the upper board. The air passes in and out between it and the sounding-box, and the strings being set in vibration give off that soft, melodious murmur which, in a more subdued tone, is heard near telegraph posts when the wires are shaken by the wind.

This is the ordinary Æolian harp, but in this country and on the Continent there are many more complicated forms of the instrument in existence. The Æolians of the four Strasburg Cathedral towers, for instance, are well known to tourists. At the castle of Baden Baden also the harps are a great attraction, and we here give a sketch of one of the loudest of these celebrated instruments.

It is set well back in the gallery, and the window opening is gradually contracted by the curious shed, of which one side is removed to show the construction, the air passing out through the grating, which is only slightly wider than the harp. Of the harp itself we give the plan and section, and to avoid fractions we retain its original measurement in mètres and centimètres--sixty-one centimètres being as nearly as possible two feet, and a mètre being a hundred centimètres, or thirty-nine inches and three-eighths.

It will be noticed that this pattern of the instrument has strings on both sides, and that the inner edge of the box is fitted with narrow sound-holes. The front of the box is of thin wood steamed into shape, and fitted round the curved ends as carefully as the sides are built into the back and belly of a violin.

In Kircher’s harp, the older form, the screen fits into a window, the instrument is hung on an iron rod, and has a great many strings stretched over broad sound-holes. The case is freely perforated, and is hung so as to half overlap the aperture which gives admittance to the air.

Kircher for a long time had the credit of being the inventor of the Æolian harp, but it is of much earlier date. It is, in truth, a very obvious contrivance, easily made, and not susceptible of much improvement. In our last figure we give its latest form, which differs from the others only in the arrangement of the screens. These are devised to throw a strong draught on to the strings, without having to be fitted into a window frame; but in this, as in all the other forms of the wind harp, it requires a pretty strong breeze to bring out its full tone.