ing through a veil of clouds, and a change even of shape will be thus produced which will impart to the object in question the semblance of a living form. The actual state of the eye itself will also greatly assist in completing such an illusion; for, in consequence of the small degree of light, the pupil expands to nearly the whole width of the iris, in order to collect every ray, and in such a condition it cannot accommodate itself to see near objects distinctly; so that the form of a body actually becomes more shadowy and confused when it comes within the very distance at which we count upon obtaining the best view of it."

"You have certainly explained the reason why bodies seen under a faint illumination may appear distorted and caricatured; indeed, I now remember that Sir Walter Scott, in his 'Pirate,' has given us a very good illustration: for Cleveland, when abandoned on Coffin-bay, is said to have seen many a dim and undefined spectre in the misty dawn. But I am still at a loss to understand how the vision I witnessed in the valley could have been conjured up," said Miss Villers.

"It was the doubtful and flickering light of the clouded moon upon the mass of white sandstone, or, in the words of Milton, that of 'a sable cloud that turned forth her silver lining on the night,"" said Mr Seymour. "It is a great law of the imagination, that a likeness in part tends to become a likeness of the whole. The sandstone presented, in the first instance, a form somewhat resembling the human figure, or some part of it, when your active imagination immediately completed the outline; just in the same way as we trace images in the fire, or castles in the clouds, or grotesque figures of men and animals on damp walls." (51.)

Major Snapwell, who expressed himself much pleased with the conversation, desired to call the attention of his friends to an adventure related in the delightful German romance of 'UNDINE,' which, he said, would confirm all he had heard upon the subject. It was as follows:

"A worthy and pious old fisherman, residing on the borders of a lake, at the foot of a deep forest, through which he had repeatedly passed without interruption, heard, on a certain evening, the very unusual trampling of a mounted steed drawing nearer and nearer, as it appeared to be emerging from the darkness of the wood. The fisherman became alarmed; and what he had fancied in many a stormy night respecting the mysteries of the forest flashed through his mind in a moment. Being thus prepared for any illusion of the senses, he raised his eyes towards the wood, and saw the figure of a man of gigantic stature, and snow-white appearance, nodding his head in a portentous manner? when an interval of reflection and a short prayer so tranquillised his disturbed nerves, that he readily perceived the strange mistake into which his heated imagination had

6

betrayed him; and so affected was he, to use his own words, that he could 'with difficulty refrain from laughing.' The white, nodding figure he had seen became transformed, in the twinkling of an eye, to what in reality it was, a small brook, long and familiarly known to him, which ran foaming from the forest, and discharged itself into the lake."

Mrs Seymour observed that in Goethe's ballad of the "ERL KING," a similar illusion is described-" of which," said she, "I only remember one stanza, but that will be sufficient for the occasion :—

'My father! my father! and saw'st thou not

The Erl King's daughter, near yon dark spot?'
'My son, my son, I see well the gleam,

'Tis the old green willow beside the stream.'

Miss Villers expressed her satisfaction at being thus convinced that all she had seen at the waterfall in the valley was but "a phantasy that had played upon her eyesight;" and having thus disposed of this part of my tale, "I doubt not," she added, "but that you will, with equal truth and satisfaction, explain the circumstance of my name having been so audibly pronounced, and from a spot which made it impossible that it should have come from any human being."

"It was the solitary spirit of the dell," said Mr Seymour, with a smile : 66 a rural spirit who is disposed to become very loquacious whenever the repose of her habitation is disturbed. I can assure you," added he, “that you are not the first person whom her gambols have surprised and terrified in the shades of evening. I presume you have discovered that I allude to that unseen musician of the airЕсно."

"Indeed, Mr Seymour, the sound could not have been the effect of an echo, for I never spoke," replied Miss Villers.

“Very likely ; but I happen to know that Mrs Seymour called you by name at the orchard gate.”

"Nor will that explain it," observed Miss Villers; "for in that case I must certainly have heard her; whereas the sound came in a very different direction, from the inaccessible rocks of sandstone."

Did

"Young lady,” said Mr Seymour, “you must forgive me for telling you that your philosophy is at fault. It is as possible to hear an echo without recognising the direct sound which produced it, as it is for two persons to be so placed as to see each other in a looking-glass, although objects might obstruct the direct view of themselves.* you never walk between an irregular wall and a row of houses, or along a valley intercepted by houses, during the ringing of a peal of bells? Nothing is more common, under such circumstances, than for the sound, instead of arriving at the ear in its true direction, to

* See page 234.

be reflected in one that is opposite to it. Now, before we quit the subject of optical illusion, let me relate an incident which occurred to myself. I presume you are all acquainted with the appearance in the grass, called a Fairy ring?""

"To be sure," said Tom, "a very dark circle of grass, around which there is generally a ring that looks as if the ground had been burnt."

"Very well; and we are now satisfied that this appearance is the consequence of the growth and decay of certain fungi, (52,) although the common people still believe that the ring is produced by the gambols of fairies. Now, then, for my story. It was on a moonlight night, last August, when strolling along a neighbouring meadow, enjoying the beauties of the evening, that I met a young farmer, an intelligent person, although a little inclined to a belief in the marvellous, who, on approaching with a hasty step, thus accosted me :'You have often ridiculed my belief in fairies, and of their being the cause of those rings which go by their name; you may now, if you please, satisfy yourself of their reality, if you will only return with me to the elm-close, which, as you know, abounds with fairy rings. Within the last few minutes I have actually seen them at their gambols under the great elm; they are, Sir, tiny beings, which, as far as I could judge at a distance, cannot be more than a few inches in height; but there they are, frisking away most merrily to tinkling music. Pray, Sir, do let us return, and satisfy yourself as well as me.' You may readily suppose that I lost no time in complying with my friend's request; and, sure enough, there they were."

“What, the fairies!" exclaimed Louisa, in astonishment.

"Have patience, my dear, and you shall hear. I confess," continued Mr Seymour, "that, at the first glance, I was almost startled into a belief in the reality of my friend's assertion; but, on approaching, the Fairy Queen and her court were changed into a circle of fungi, to which the shadowy play of the leaves of the neighbouring tree had, in the light of the moon, given the appearance of a fantastic motion, while their waving and rustling sounds mimicked wild music, The illusion, I will admit, was well calculated to impose upon the credulous countryman."

"So then," exclaimed the vicar, whimsically quoting the words of Falstaff, "these were not fairies! I was three or four times in the thought they were not fairies.'"*

"Well," said Louisa, "I suppose your young farmer was now satisfied."

"Not at all," answered her father, "he still maintained that he had seen the fairies, observing that it was a common trick with them,

* Merry Wives of Windsor.

when watched, to turn themselves all at once into flowers, such as lilies, tulips, and the like."

"Or to take shelter in the purple bell of the foxglove,"* suggested

the major.

The young party were much amused by this anecdote, and the vicar took the opportunity to explain, on natural principles, several superstitious appearances recorded in ancient legends.

Mr Seymour now proposed to dedicate an hour to the explanation of the several toys which owe their action to atmospheric vibration; "I shall then," said he, addressing Miss Villers, "be at your service to interrogate the spirit of the valley; and the children, whom I intend to accompany us, will be thus better prepared to comprehend the theory of the echo.

"Musical instruments, amongst which I include the toys to which I have alluded, may be classed under three heads:-stringed instruments, such as the harp, violin, &c.; wind instruments, as the flute and trumpet; and instruments of percussion, as the tabor and drum.” "And which kind do you consider the most ancient?" asked Miss Villers.

"Wind instruments, madam, most unquestionably," cried Mr Twaddleton. "Diodorus ascribed their invention to the accidental notice of the whistling of the wind in the reeds on the banks of the Nile; and the poet Lucretius maintained a similar opinion."

66 I really, my dear Sir, cannot see any good reason for giving this preference, in point of antiquity, to wind instruments," said Mr Seymour. "The lyre, or harp, is, surely, as ancient as any instrument on record. The mythologist ascribes the idea of producing sound by the vibration of a string to Apollo; which is said by Censorinus to have suggested itself to him, on his hearing the twang of the bow of his sister Diana. With respect to instruments of percussion, it may be reasonably supposed that the sonorous ringing of hollow bodies, when struck, must have very soon suggested their invention to mankind; but I really consider any research into a question of such obscurity as uninteresting as it must be hopeless; let us rather devote our attention to the philosophy of these instruments. I have stated that they may be referred to three principal classes; but I must at the same time observe that, in some cases, the vibrations of solid bodies are made to co-operate with those of a given portion of air; for example, trumpets and various horns may be said to be mixed wind instruments, since their sound is produced by the joint vibrations of the air and a solid body: and in certain stringed

instruments, as in the violin, the immediate effect of the strings is increased by means of a sounding-board, which appears to be agitated by their motion, and to act more powerfully on the air than the strings could have done alone."

"I apprehend that this mixture must obtain more or less in all instruments," said the vicar.

"Not at all. The flute, flageolet, humming-top, and the cavity of the mouth in whistling, may be considered as simple wind instruments, in which the quality of the sound is alone determined by the vibrations of the air. I have already explained the manner in which the oscillations of a string excite aërial undulations, and thus produce sound; and you have seen that the nature of these sounds is determined by the length and thickness of such strings: the theory equally applies to wind instruments, in which case a column of air corresponds with the string, the volume and length of which determine the sound. In the harp, the strings are constructed of different lengths and dimensions; and so, in the Syrinx, or Pan's pipes, is the volume of air adjusted to the respective notes by the size and length of the reeds; but, in the violin, the lengths of the strings are altered at pleasure by pressing them down on the finger-board; and, in like manner, the effective length of the flute is changed by the opening or shutting the holes made at proper distances in them; the opening of a hole at any part being the same in effect as if the pipe were cut off a little beyond it."

Mr Seymour and the vicar then entered into a long discussion, with which it is not our intention to swell our history, or to exhaust the patience of the reader; we shall, however, with his permission, collect from the mass some of the more interesting facts, and present them in as condensed a form as may be consistent with perspicuity. In speaking of the Jew's harp, a little instrument with which every schoolboy is well acquainted, the vicar stated that its origin was lost in the long lapse of time; but that it was in very common use throughout Europe, and more especially in the Netherlands and the Tyrol, where it was the delight of the peasants and their families. He also said that it was known in Asia, and that the Greeks of Smyrna called it, in imitation of its sound, biambo.* The name by which it is now known, he observed, was evidently derived from the Jews, who were formerly the great vendors of it, and of other toys, throughout Europe, although he stated that his friend Mr Prybabel was of opinion that it was a corruption of jaw's harp. Mr Seymour described its construction, and the theory of its action. It is com

* In "The Notes of a Tour among the | the Spaniards, and that no young galIndian Tribes of Southern Chili," by lant is considered fully equipped to lay Edmund Ruel Smith, we are informed siege to a lady's heart, if unprovided that the Jew's harp is as national with with that instrument, dangling by a those barbarians, as the guitar is with string of beads from his neck.