Upon the same principle does the resonance, or reciprocated vibrations of columns of air, depend. We are much indebted to Mr. Wheatstone for our knowledge of this branch of acoustics; he has shown that, if a tuning-fork or a bell be sounded before a tube inclosing a column of air of the necessary length, the original sound will be augmented by the rich resonance of that air; and that the sounds of tuning-forks, if held before the cavity of the mouth, may be reciprocated most intensely by adjusting the alterable volume of air contained within it to the pitch of the instrument; by placing, for instance, the tongue, &c. in the position for the nasal continuous sound of ng (in song), and then altering the aperture of the lips, until the loudest sound was obtained, he readily accomplished his object.
If two vibrating tuning-forks, differing in pitch, be held over a closed tube, furnished with a moveable piston, either sound may be made to predominate, by so altering the piston as to obtain the exact column of air which will reciprocate the required sound. The same result may be obtained by selecting two bottles (which may be tuned with water) each corresponding to the sound of a different tuning fork; on bringing both tuning-forks to the mouth of each bottle alternately, that sound only will be heard, in each case, which is reciprocated by the unisonant bottle; or, in other words, by that bottle which contains a column of air susceptible of vibrating in unison with the fork.
Among the Javanese instruments brought to England by the late Sir Stamford Raffles, there is one called the gender, in which the resonances of columns of air are employed to augment, we might almost say to render audible, the sounds of vibrating metallic plates. Under each of these plates is placed an upright bamboo, containing a column of air of the proper length to reciprocate the lowest sound of such plate. If the aperture of the bamboo be covered with pasteboard, and its corresponding plate be struck, a number of acute sounds only (depending on the more numerous subdivisions of the plate) will be heard; but, on removing the pasteboard, an additional deep rich tone is produced by the resonance of the column of air within the tube.
It is only by a knowledge of this principle that the theory of the Guimbarde, or Jew’s harp, can be well understood.
Note 49, p. [300].--The Jew’s harp.
The Memoires of Madame de Genlis first made known the astonishing powers of a poor German soldier on the Jew’s harp. This musician was in the service of Frederick the Great, and finding himself one night on duty under the windows of the king, played the Jew’s harp with so much skill, that Frederick, who was a great amateur of music, thought he heard a distinct orchestra. Surprised on learning that such an effect could be produced by a single man with two Jew’s harps, he ordered him into his presence; the soldier refused, alleging that he could only be relieved by his colonel; and that, if he obeyed, the king would punish him the next day for having failed to do his duty. Being presented the following morning to Frederick, he was heard with admiration, and received his discharge and fifty dollars. This artist, whose name Madame de Genlis does not mention, is called Koch; he has not any knowledge of music, but owes his success entirely to a natural taste. He has made his fortune by travelling about, and performing in public and private; and is now living retired at Vienna, at the advanced age of more than eighty years. He used two Jew’s harps at once, in the same manner as the peasants of the Tyrol; and produced, without doubt, the harmony of two notes struck at the same moment, which was considered by the musically-curious as somewhat extraordinary, when the limited powers of the instrument were remembered. It was Koch’s custom to require that all the lights should be extinguished, in order that the illusion produced by his playing might be increased.
It was reserved, however, for Mr. Eulenstein to acquire a musical reputation from the Jew’s harp. After ten years of close application and study, this young artist has attained a perfect mastery over this untractable instrument. In giving some account of the Jew’s harp, considered as a medium for musical sounds, we shall only present the result of his discoveries. This little instrument, taken singly, gives whatever grave sound you may wish to produce, as a third, a fifth, or an octave. If the grave tonic is not heard in the bass Jew’s harp, it must be attributed not to the defectiveness of the instrument, but to the player. In examining this result, you cannot help remarking the order and unity established by nature in harmonical bodies, which places music in the rank of exact sciences. The Jew’s harp has three different tones; the bass tones of the first octave bear some resemblance to those of the flute and clarionet; those of the middle and high to the vox humana of some organs; lastly, the harmonical sounds are exactly like those of the harmonica. It is conceived that this diversity of tones affords already a great variety in the execution, which is always looked upon as being feeble and trifling, on account of the smallness of the instrument. It was not thought possible to derive much pleasure from any attempt which could be made to conquer the difficulties of so limited an instrument; because, in the extent of these octaves, there were a number of spaces which could not be filled up by the talent of the player; besides, the most simple modulation became impossible. Mr. Eulenstein has remedied that inconvenience, by joining sixteen Jew’s harps, which he tunes by placing smaller or greater quantities of sealing-wax at the extremity of the tongue. Each harp then sounds one of the notes of the gamut, diatonic or chromatic; and the performer can fill all the intervals, and pass all the tones, by changing the harp. That these mutations may not interrupt the measure, one harp must always be kept in advance, in the same manner as a good reader advances the eye, not upon the word which he pronounces, but upon that which follows.
Note 50, p. [316].--Verbal telegraph.
This project has lately been revived; in a late number of the Revue Encyclopédique there is a proposal to communicate verbal intelligence, in a few moments, to vast distances; and this not by symbols, as in the Telegraph, but in distinct articulate sounds uttered by the human voice. The plan is said to have originated with an Englishman, Mr. Dick, according to whose experiments the human voice may be made intelligible at the distance of twenty-five or thirty miles. It has been stated, in [Note 44], that the celebrated Biot had ascertained that sound travels more than ten times quicker when transmitted by solid bodies, or through tubes, than when it passes through the open air; at the distance of more than half a mile the low voice of a man was distinctly heard. Father Kircher relates in some of his works, that the labourers employed in the subterranean aqueducts of Rome heard each other at the distance of several miles. The note which follows was published in the early edition of this work, before the subject attracted any notice, or any railroad had been completed. It is therefore reprinted without alteration.
Note 51, p. [316].--Electrical telegraph.