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tion was assigned to the gods. Some say it was discovered by Mercury, while others attribute it to Apollo, or Orpheus. Most writers, however, consider Mercury to have the highest title to the honour. Apollodorus gives a pretty fable, to account for the invention of the lyre: the waters of the Nile, when they overflowed their banks, threw a turtle on the shore, which died, and was not swept away by the retiring flood. Exposed to the atmosphere, the animal substance was soon decomposed, and nothing was left but the shell and the tense fibres. The Egyptian Mercury, when walking by the shore, observed and examined the remains of the animal, and immediately afterwards constructed the lyre in imitation of what he had seen.

Although the ancients had many stringed instruments, more than we are acquainted with, there are only two representations of instruments with necks-one on the obelisk at Rome, and one in the sepulchral grotto in the city of Tarquina. The allusions to musical instruments are frequent in the Greek and Roman writers; but they do not generally give a description of them. Little dependence can, on the other hand, be placed upon the various representations in ancient sculpture, for none but the most simple instruments are introduced..

CHAPTER VI.

VIBRATING PLATES AND BARS.

ALL solids, when in a state of vibration, give out sounds. The pitch of these sounds depends on the frequency of the vibrations; and their quality and strength are governed by the nature of the vibrating body, the extent of the undulations, and other mechanical circumstances.

In the last chapter, we have considered the vibration of one class of solids, namely, strings. The motion in these bodies is produced by an external tension ; but in plates, bars, bells, and vessels of various kinds, the vibrations result from their own elasticity. When speaking of strings, we took occasion to describe the nature of longitudinal vibrations, not so much because it was a subject strictly belonging to that part of our inquiry, but because it assisted our investigations. Referring again to the character of the vibrations produced in solids, it will be remembered that an undulation may be propagated through them in the same manner as in an elastic fluid, and obeys the same laws; or they may be struck in the direction of their length, and the vibration is then said to be longitudinal. The nature of these longitudinal vibrations may be still further illustrated by a description of the euphone.

The euphone is an instrument invented by Dr. Chladni. This philosopher, when examining the nature of sonorous

bodies, imagined the possibility of producing musical sounds by rubbing glass tubes longitudinally. "I was quite aware," he says, "that tones could not be obtained by merely rubbing glass tubes, and it therefore became a question of great difficulty to determine the manner in which the instrument should be constructed." For more than eighteen months his mind seems to have been engrossed with the idea of producing a new instrument; yet the difficulties which stood in his way were augmented rather than diminished. The manner in which he at last obtained his object is remarkable, but is related by himself, and may therefore be repeated. In the summer of 1789, he returned home in the evening, exhausted with walking, and fell asleep in his chair, but had scarcely closed his eyes when the arrangement which he had been so long seeking was presented to his mind. He immediately started up, recovering all his enthusiasm, and after a few experiments, convinced himself that his object had been attained. In March of the following year, he had completed his instrument, and was able to play upon it a few simple tunes. In every respect it answered his expectations, but in its construction was so deficient in strength that it was constantly needing repair, and to have conveyed it a mile, he says, would have almost totally destroyed it.

The euphone, a name which signifies an instrument that has a pleasant sound, consists of forty-one fixed and parallel cylinders of glass, of equal length and thickness. They were at first, for want of better materials, constructed of thermometer tubes, the whole and half tones being distinguished by a coating of sealing-wax on the under side. Tubes of different colours are now employed for the same purpose. The euphone,

COMPARISON OF THE EUPHONE AND HARMONICA.

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in its external appearance, resembles a small writing-desk, which, when opened, presents a series of glass tubes, about the thickness of a quill, and about sixteen inches long. In the back part of the instrument, there is a perpendicular sounding-board, into which the tubes are fixed. When used, the tubes are wetted with a sponge, and stroked in the direction of their length with wet fingers, so that the intensity of the tone may be varied by a greater or less pressure.

From the pains which the Doctor has taken to compare his own instrument with the harmonica, it would appear that some persons in his own day considered it as only a modification of that instrument. He has given seven reasons why an unprejudiced person should prefer the euphone.

1. It is less complex in its construction, and requires neither turning nor stamping, but merely the motion of the fingers.

2. The tone is given out as soon as touched, and the full power of the instrument may be obtained; whereas in the harmonica the intensity of the tones must increase gradually.

3. It has more distinctness in quick passages, as the tones do not resound for so long a time.

4. The unison is more perfect than in the harmonica, for in that instrument it is difficult to obtain glasses which in every part shall give tones with mathematical exactness. The euphone, however, he acknowledges, is as difficult to tune as the harmonica.

5. It does not affect the nerves of the performer, for he scarcely feels the slightest agitation in the fingers; but when playing the harmonica, particularly the concords of low notes, the vibrations are felt throughout the whole system.

6. The expense of the instrument is less than the harmonica.

7. When any portion of the instrument is broken, it is easily repaired, and at a small expense.

These are Chladni's reasons for recommending the euphone in preference to the harmonica. Whether he has been guided by the prejudice which an inventor naturally feels for his own instrument, we cannot pretend to state, as we have not hitherto met with an opportunity of examining its claims to attention.

Sir John Herschel still further explains the construction of this instrument, in the following passage: “The longitudinal vibrations of a rod of glass, excited by rubbing it with a wet cloth, may also be used to excite vibrations in a given point of a solid perpendicular to its surface, by applying its end to it, or cementing it to the solid by mastic. In this way Chladni applied it to draw forth the sounds of glass vessels, (which, when hemispherical, and of sufficient size and even thickness, are remarkably rich and melodious,) in an instrument which he called the euphone, exhibited by him in Paris and Brussels. The principle of this instrument was at the same time concealed; but the enigma was subsequently solved by M. Blanc, who on his part made the same remark, and applied it to a similar purpose." The euphone, therefore, although producing sounds by longitudinal vibrations, is also an illustration of the manner in which vibrations are communicated-a subject to be hereafter considered.

Although musical sounds are sometimes obtained from solids by longitudinal vibrations, the most common method of producing undulations is by forcibly disturbing the exter

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