extending waves, but of vibrations, which are composed of a motion forwards and backwards: the undulations of the air differ also from those of the water, in not being confined to a plane, but in diverging in all directions from the centre; or, in other words, the aërial undulations are spherical." "It is a very puzzling subject," cried Tom.

"I cannot understand," said Louisa, "how the motion of the air can extend so as to convey sound to a distance, if, as you say, the air moves backwards as well as forwards."

"I see your difficulty, and will endeavour to remove it : attend to me. The first set of undulations which are produced immediately around the sonorous body, by pressing against the contiguous air, condense it. The condensed air, though impelled forward by the pressure, reacts on the first set of undulations, driving them back again. The second set, which have been put in action, in their turn, communicate their motion, and are themselves driven back by reaction. Thus there is a succession of waves in the air, corresponding with the succession of waves in the water."

"Now I understand why sound requires some time to travel from a distant object to the ear, as you explained to us upon a former occasion,' " said Louisa.

"But you have not yet told us what renders a body sonorous," observed Tom.

"Its elasticity: a ball of damp clay, which does not possess this property, will produce no other sound when struck, but that which arises from the condensation of the small portion of air between the clay and the hammer which strikes it. A hollow ball of brass will produce more sound, because it is elastic; but still very little effect will arise from this, since a ball is the worst shape for admitting of vibration, on account of its forming an arch or dome, in every direction, so that one part stiffens and sustains the other: but if such a ball be divided, and the edge of one half of it struck, a loud, clear, and distinct tone will be produced; because a hemisphere will admit of the exertion of elasticity, or of momentary change of figure, which is conducive to the perfection of sound; and accord

* See page 37.

T

ingly the bells used for clocks, and for musical purposes, have generally such a figure."

"I see, clearly," said Louisa, "that it is the vibration of a sonorous body that communicates the necessary motions to the air; and I suppose that a body vibrates in proportion to its elasticity."

"Certainly it does: but to render this subject still more intelligible, I have prepared a diagram."

Mr. Seymour then exhibited a figure, of which the annexed is a copy, and proceeded to explain it in the following

manner :

B

*

"You are well aware that an elastic body, after having been struck, not only returns to its former situation, but, having acquired momentum by its velocity, like the pendulum or swing, springs out on the opposite side. If, then, I draw the string A B, which is made fast at both ends, to c, it will not only return to its original position, but proceed onwards to D. This is the first vibration, at the end of which it will retain sufficient velocity to bring it to E, and back again to F, which constitutes its second vibration, the third vibration will carry it only to u and H and so on, till the resistance of the air destroys its motion."

"That is exactly like the swing or pendulum," said Tom. "As you are struck with the resemblance, take care and preserve the remembrance of it; for I shall hereafter have occasion to revert to it."

"As I now understand how sound is produced and carried to a distance, I should much like to learn the cause of dif ferent tones," said Louisa.

"Fond as you are of music, my dear Louisa, I am not surprised at the wish you have just expressed to become acquainted with the nature of musical sounds; I shall, See page 158 et seq.

therefore, endeavour to convey, in as simple a manner as possible, the theory which has been proposed for their explanation. I think you will immediately perceive that, if the aërial waves, which I have endeavoured to describe, should be irregular, or run into each other, there must arise a confusion of sounds; thus discords may be readily imagined to be produced whenever a second vibration shall commence before the first is finished, so as to meet it halfway on its return, and interrupt it in its course. In like manner may we conceive the general nature of those arrangements upon which unison and concord depend; where the vibrations are performed in equal times, the same tone is produced by both, and they are said to be in unison; but concord, as you well know, is not confined to unison, for two different tones harmonize in a variety of cases. If, for example, the particles of one sonorous body vibrate in double the time of another, the second vibration of the latter will strike the ear at the same instant as the first vibration of the former; and this is the 'concord of an octave.' When the vibrations are as 2 to 3, the coincidence will be at every third vibration of the quickest, which, therefore, is the next degree of perfection, and is called a 'diapente,' or 'fifth,' while the vibration of 3 to 4 will produce the diatessaron,' or 'fourth;' but this and the next which follow in order are not so agreeable to the judicious ear, and are therefore called 'imperfect concords;' while discord is produced by the vibrations confusedly interfering with each other."

Louisa here inquired whether the difference in the acuteness of a sound did not depend upon the nature of the vibrations; and her father, in reply, stated that it depended entirely upon the degree of quickness with which the vibrations were performed: the slower the vibration, the graver the tone; the quicker, the more acute.*

"But, if I strike any one note of the instrument repeatedly, whether quickly or slowly, it always gives the same tone," observed Louisa.

"To understand that fact," replied her father, "you

* The number of vibrations made by the wings of insects, as before stated, has been ingeniously deduced from the tone which they produce.

must remember that the vibrations of bodies are regulated by laws very similar to those of the pendulum; consequently the duration of the vibrations of strings or chords depends upon their length and thickness; for if two strings of equal magnitude, but with their lengths as 2 to 1, be equally stretched, their vibrations will be in the same ratio; therefore, the shortest will make two vibrations, while the longest makes one; but the vibrations of the same string will always be the same whether it be struck quickly or slowly, upon the principle of the isochronous property of the pendulum, already described. It is also worthy of remark that however much the sound-vibrations may vary in quickness, or pitch, they travel forward at the same rate of progression ; for in a ring of bells, the sound of every tone is heard at two or three miles' distance, in the same order that the bells are struck; and so it is with music, distance may render it fainter, but it does not alter the tune."

Let us now take leave of this subject, for I am quite sure that my young friends have already received more than they can profitably carry away," said the vicar.

"I submit, my good sir; and in return for my compliance, use your influence with Miss Villers, and induce her to favour us with a practical illustration of our subject upon the pianoforte."

"Most cheerfully; but my intercession is quite unnecessary, for I am sure that our fair friend is no disciple of Tigellius."*

"I am ever ready, sir, to comply with the wishes of those I respect. I consider the caprice which our sex too often displays upon these occasions, as not only a breach of good taste, but an evidence of unpardonable vanity."

* Horat. Sat. lib. i. sat. 3.

A LEARNED DISCUSSION, TOUCHING THE SUPERIOR POWERS OF ANCIENT, COMPARED WITH MODERN MUSIC.-MR. SEYMOUR COMBATS THE PREJUDICES OF THE VICAR, AND SUPPORTS THE CLAIMS OF MODERN MUSIC. -THE IMPORTANCE OF NATIONAL AIRS AND BALLADS.-DIBDIN'S SONGS, AND MONK LEWIS'S BALLADS.-POETRY THE SISTER OF MUSIC.THE SIRENS OF HOMER.-THE MAGIC OF MUSIC, A GAME HERE DESCRIBED FOR THE FIRST TIME. THE VICAR'S PERFORMANCE.-ADVENTURES BY MOONLIGHT.-SPIRITS OF THE VALLEY, AND A SPECTRE AT THE WATERFALL. GOOD NIGHT.

AFTER the several conversations related in the foregoing pages, the reader will not be surprised to find that the opinion of the vicar regarding the superior attainments of Miss Villers, had daily acquired an increasing ascendancy; and had that lady been free and disengaged, and could "dear Mr. Twaddleton" have obtained a slice of one of those Scandinavian apples to which Mr. Seymour had lately alluded, we are by no means sure, in spite of his bachelor tendencies, that the current of his admiration might not have murmured in a softer channel:-but that is beside our present purpose. We only desire to impress upon our readers the high amount of respect he entertained for her abilities and judgment; and it was under such a conviction that he was induced to submit a question which gave rise to the learned discussion we are now about to relate.