In sleep the whole nervous frame is relaxed, while the heart and the lungs seem more forcibly exerted. This fuller circulation produces also a swelling of the muscles as they always find who sleep with ligatures on any part of their body. This increased circulation may also be considered as a kind of exercise, which is continued through the frame; and by this the perspiration becomes more copious, although the appetite for food is entirely taken away. Too much sleep dulls the apprehension, weakens the memory, and unfits the body for labour. On the contrary, sleep too much abridged emaciates the frame, produces melancholy, and consumes the constitution. It requires some care, therefore, to regulate the quantity of sleep, and just to take as much as will completely restore Nature without oppressing it. The poor, as Otway says, sleep little; forced by their situation to lengthen out their labour to their necessities, they have but a short interval for this pleasing and enerving refreshment. I have ever been of opinion that bodily labour demands a less quantity of sleep than mental. Labourers and artizans are generally satisfied with about seven hours; but I have known some scholars who usually slept nine, and perceived their faculties no way impaired by oversleeping.

The famous Philip Barrettiere-who was considered as a prodigy of learning at the age of fourteen-was known to sleep regularly twelve hours in the twenty-four; the extreme activity of his mind when awake in some measure called for an adequate alternation of repose; and I am apt to think that when students stint themselves in this particular they lessen the waking powers of the imagination, and weaken its most strenuous exertions. Animals that seldom think, as was said, can very easily dispense with sleep; and of men, such as think least will probably be satisfied with the smallest share. A life of study, it is well known, unfits the body for receiving this gentle refreshment; the appoaches of sleep are driven off by thinking: when, therefore, it comes at last, we should not be too ready to interrupt its continuance.

Sleep is, indeed, to some a very agreeable period of their existence and it has been a question frequently asked in schools-Which is most happy, the man who was a beggar by night and a king by day, or he who is a beggar by day and a king by night? It is given in favour of the nightly monarch by him who first started the question: "For the dream," says he, "gives the fuli enjoyment of the dignity without its attendant inconveniences; while, on the other hand, the king, who supposes himself degraded, feels all the misery of his fallen fortune without trying to find the comforts of his humble situation. Thus, by day, both states have their peculiar distresses; but by night. the exalted beggar is perfectly blessed, and the king completely miserable." All this, however, is rather fanciful than just; the plea sure dreams can give us seldom reaches to our waking pitch of happiness: the mind often, in the midst of its highest visionary satisfactions, demands of itself whether it does not owe them to a dream, and frequently awakes with the reply.

But it is seldom-except in cases of the highest delight or the most extreme uneasiness-that the mind has power thus to disengage itself from the dominion of fancy. In the ordinary course of its operations it submits to those numberless phantastic images that succeed each other, and which, like many of our waking thoughts, are generally forgotten. Of these, however, if any, by their continuance, affect us strongly, they are then remembered; and there have been some who felt their impressions so strongly as to mistake them for realities, and to rank them among the past actions of their lives. There are others upon whom dreams seem to have a very different effect; and who, without seeming to remember their impressions the next morning, have yet shown by their actions during sleep that they were very

powerfully impelled by their dominion. We have numberless instances of such persons who, while asleep, have performed many of the ordinary duties to which they have been accustomed when waking, and, with a ridiculous industry, have completed by night what they failed doing by day. We are told in the German Ephemerides of a young student who, being enjoined a severe exercise by his tutor, went to bed despairing of accomplishing it. The next morning awaking, to his great surprise he found the task fairly written out, and finished in his own hand-writing. He was at first, as the account has it, induced to ascribe this strange production to the operation of an infernal agent; but his tutor, willing to examine the affair to the bottom, set him another exercise still more severe than the former, and took precautions to observe his conduct the whole night. The young gentleman, upon being so severely tasked, felt the same inquietude that he had done on the former occasion; went to bed gloomy and pensive, pondering on the next day's duty, and, after some time, fell asleep. But shortly after, his tutor, who continued to observe him from a place that was concealed, was surprised to see him get up, and very deliberately go to the table, where he took out pen, ink, and paper, drew himself a chair, and sat very methodically to thinking: it seems that his being asleep only served to strengthen the powers of his imagination; for he very quickly and easily went through the task assigned him, put his chair aside, and then returned to bed to take out the rest of his nap. What credit we are to give to this account I will not pretend to determine; but this may be said, that the book from whence it is taken has some good marks of veracity-for it is very learned and very dull, and is written in a country noted, if not for truth, at least for want of invention.

The ridiculous history of Arlotto is well known, who has had a volume written containing a narrative of the actions of his life, not one of which was performed while he was awake. He was an Italian Franciscan friar, extremely rigid in his manners, and remarkably devout and learned in his daily conversation. By night, however, and during his sleep, he played a very different character from what he did by day, and was often detected in very atrocious crimes. He was at one time detected in actually attempting a rape, and did not awake till the next morning, when he was surprised to find himself in the hands of justice. His brothers of the convent often watched him while he went very deliberately into the chapel, and there attempted to commit sacrilege. They sometimes permitted him to carry the chalice and the vestments away into his own chamber, and the next morning amused themselves at the poor man's consternation for what he had done. But of all his sleeping transgressions, that was the most ridiculous in which he was called to pray for the soul of a person departed. Arlotto, after having devoutly performed his duty, retired to a chamber which was shown him to rest; but there he had no sooner fallen asleep, than he began to reflect that the dead body had got a ring upon one of the fingers, which might be useful to him; accordingly, with a pious resolution of stealing it, he went down, undressed as he was, into a room full of women, and, with great composure, endeavoured to seize the ring. The consequence was that he was taken before the Inquisition for witchcraft; and the poor creature had like to have been condemned, till his peculiar character accidently came to be known; however, he was ordered to remain for the rest of life in his own convent, and upon no account whatsoever to stir abroad.

What are we to say of such actions as these, or how account for this operation of the mind in dreaming? It would seem that the imagination by day as well as by night is always employed, and that often against our wills it intrudes where it is least commanded or desired. While awake and in health this busy principle

cannot much delude us; it may build castles in the air, and raise a thousand phantoms before us; but we have every one of the senses alive to bear testimony to its falsehood. Our eyes show us that the prospect is not present; our hearing and our touch depose against its reality; and our taste and smelling are equally vigilant in detecting the impostor. Reason, therefore, at once gives judgment upon the cause; and the vagrant intruder, Imagination, is imprisoned or banished from the mind. But in sleep it is otherwise; having, as much as possible, put our senses from their duty-having closed the eyes from seeing, and the ears, taste, and smelling from their peculiar functions, and having diminished even the touch itself by all the arts of softness-the ima gination is then left to riot at large, and to lead the un derstanding without an opposer. Every incursive idea then becomes a reality; and the mind, not having one power that can prove the illusion, takes them for truths. As in madness, the senses, from struggling with the imagination, are at length forced to submit, so in sleep they seem for a while soothed into the like submission; the smallest violence exerted upon any one of them, however, rouses all the rest in their mutual defence; and the imagination, that had for a while told its thousand falsehoods, is totally driven away, or only permitted to pass under the custody of such as are every moment ready to detect its imposition.

CHAP. VII.

OF SEEING.

Having mentioned the senses as correcting the errors of the imagination, and as forcing it in some measure to bring us just information, it will naturally follow that we should examine the nature of those senses themselves; we shall thus be enabled to see how far they also impose on us, and how far they contribute to correct each other. Let it be observed, however, that in this we are neither giving a treatise of optics or phonics, but a history of our own perceptions; and to those we chiefly confine ourselves.

The eyes very soon begin to be formed in the human embryo, and in the chicken also. Of all the parts which the animal has double the eyes are produced the soonest, and appear the most prominent. It is true, indeed, that in viviparous animals, and particularly in man, they are not so large in proportion at first as in the oviparous kinds; nevertheless, they are more speedily developed when they begin to appear than any other parts of the body. It is the same with the organ of bearing; the little bones that compose the internal parts of the ear are entirely formed before the other bones, though much larger, have acquired any part of their growth or solidity-hence it appears that those parts of the body which are furnished with the greatest quantity of the nerves are the first in forming. Thus the brain and the spinal-marrow are the first seen begun in the embryo; and in general it may be said, that wherever the nerves go or send their branches in great numbers, there the parts are soonest begun, and the most completely finished.

If we examine the eyes of a child some hours, or even some days, after its birth, it will be easily discerned that it as yet makes no use of them. The humours of the organ not having acquired a sufficient consistence, the rays of light strike but confusedly upon the retina, or expansion of the nerves at the back of the eye. It is not till about a month after they are born that children fix them upon subjects, for before that time they turn them indiscriminately everywhere, without appearing to be affected by any. At six or seven weeks old they plainly discover a choice in the obiects of their attention;

they fix their eyes upon the most brilliant colours, and seen peculiarly desirous of turning them towards the light. Hitherto, however, they only seem to fortify the organ for seeing distinctly; but they have still many illusions to correct.

The first great error in vision is that the eye inverts every object; and it in reality appears to the child, until the touch has served to undeceive it, turned upside down. A second error in vision is, that every object appears double. The same object forms itself distinctly upon each eye, and is consequently seen twice. This error, also, can only be corrected by the touch; and although in reality every object we see appears inverted and double, yet the judgment and habit have so often corrected the sense that we no longer submit to its imposition, but see every object in its just position the very instant it appears. Were we, therefore, deprived of feeling, our eyes would not only misrepresent the situation, but also the number of all things round us.

To convince us that we see objects inverted, we have only to observe the manner in which images are represented coming through a small hole in a dark room. If such a small hole be made in a dark room, so that no light can come in but through it, all the objects without will be painted on the wall behind, but in an inverted position, and their heads downwards; for as all the rays which pass from the different parts of the objects without cannot enter the hole in the same extent which they had in leaving the object, since, if so, they would require the aperture to be as large as the object; and as each part and every point of the object sends forth the image of itself on every side, and the rays which form these images pass from all points of the object as from so many centres, so such only can pass through the small aperture as come in opposite directions. Thus the little aperture becomes a centre for the entire object, through which the rays from the upper parts as well as from the lower parts of it pass in converging directions; and consequently they must cross each other in the central point, and thus paint the objects behind upon the wall in an inverted position. It is in like manner easy to conceive that we see all objects double, whatever our present sensations may tell us to the contrary; for, to convince us of this, we have only to compare the situation of any one object on shutting one eye, and then compare the same situation by shutting the other. If, for instance, we hold up a finger and shut the right eye, we shall find it hide a certain part of the room; if again reshutting the other eye, we shall find that part of the room visible, and the finger seeming to cover a part of the room that had been visible before. If we open both eyes, however, the part covered will appear to lie between the two extremes. But the truth is, we see the object our finger had covered, one image of it to the right and the other to the left, but from habit suppose that we see but one image placed upon both our sense of feeling having corrected the errors of sight. And thus, also, if instead of two eyes we had two hundred, we should fancy the objects increased in proportion, until one sense had corrected the errors of another.

The having two eyes might thus be said to be rather an inconvenience than a benefit, since one eye would answer the purposes of sight as well, and be less liable to illusion. But it is otherwise; two eyes greatly contribute, if not to distinct, at least to extensive vision. When an object is placed at a moderate distance, by the means of both eyes we see a larger share of it than we possibly could with one-the right eye seeing a greater portion of its right side, and the left eye of its corres pondent side. Thus both eyes in some measure see round the object; and it is this that gives it in nature that bold relievo or swelling with which they appear, and which no painting, how exquisite soever, can attain to. The painter must be contented with shading on a flat surface,

but the eyes in observing Nature do not behold the shading only, but a part of the figure also lies behind these very shadings, which gives it that swelling which painters so ardently desire, but can never fully imitate. There is another defect which either of the eyes, taken singly, would have, but which is corrected by having the organ double. In either eye there is a point which has no vison whatsoever; so that if one of them only is employed in seeing, there is a part of the object to which it is always totally blind. This is that part of the optic nerve where its vein and artery run; which being insensible, that point of the object that is painted there must continue unseen. To be convinced of this, we have only to try a very easy experiment. If we take three black patches and stick them upon a white wall, about a foot distant from each other, each about as high as the eye that is to observe them; then retiring six or seven feet back, and shutting one eye, by trying for some time, we shall find that while we distinctly behold the black spots that are to the right and left, that which is in the middle remains totally unseen; or, in other words, when we bring that part of the eye where the optic artery runs to fall upon the object, it will then become invisible. This defect, however, in either eye is always corrected by both, since the part of the object that is unseen by one will be very distinctly perceived by the other.

Besides the former defects, we can have no idea of distances from the sight without the help of touch. Naturally every object we see appears to be within our eyes; and a child who has as yet made but little use of the sense of feeling must suppose that everything it sees makes a part of itself. Such objects are only seen more or less bulky as they approach or recede from its eyes; so that a fly that is near will appear larger than an ox at a distance. It is experience alone that can rectify this mistake; and a long acquaintance with the real size of every object quickly assures us of the distance at which it is seen. The last man in a file of soldiers appears in reality much less, perhaps ten times more diminutive, than the man next to us; however, we do not perceive this difference, but continue to think him of equal stature; for the numbers we have seen thus lessened by distance, and have found by repeated experience to be of the natural size, when we come closer instantly corrects the sense, and every object is perceived with nearly its natural proportion. But it is otherwise if we observe objects in such situations as we have not had sufficient experience to correct the errors of the eye; if, for instance, we look at men from the top of a high steeple, they in that case appear very much diminished, as we have not had a habit of correcting the sense in that position.

Although a small degree of reflection will serve to convince us of the truth of these positions, it may not be amiss to strengthen them by an authority which cannot be disputed. Mr. Cheselden having couched a boy of thirteen of a cataract who had hitherto been blind, and thus at once having restored him to sight, curiously marked the progress of his mind upon that occasion. This youth, though he had been till then incapable of seeing, yet was not totally blind, but could tell day from night, as persons in his situation always may. He could also, with a strong light, distinguish black from white, and either from the vivid colour of scarlet; how ever, he saw nothing of the form of bodies; and with out a bright light not even colours themselves. He was at first couched only in one of his eyes; and when he saw for the first time, he was so far from judging of distances, that he supposed his eyes touched every object that he saw, in the same manner as his hands might be said to feel them. The objects that were most agreeable to him were such as were of plain surfaces and regular figures; though he could as yet make no judgment whatever of their different forms, nor give a rea

son why one pleased him more than another. Although he could form some idea of colours during his state of blindness, yet that was not sufficient to direct him at present; and he could scarcely be persuaded that the colours he now saw were the same with those he had formerly conceived such erroneous ideas of. He delighted most in green; but black objects, as if giving him an idea of his former blindness, he regarded with horror. He had, as was said, no idea of forms, and was unable to distinguish one object from another, though never so different. When those things were shown him which he had been formerly familiarized to by his feelings, he beheld them with earnestness, in order to remember them a second time; but, as he had too many to recollect at once, he forgot the greatest number; and for one he could tell after seeing, there was a thousand he was totally unac quainted with. He was very much surprised to find that those things and persons he loved best were not the most beautiful to be seen; and even testified displeasure in not finding his parents so handsome as he conceived them to be. It was near two months before he could find that a picture resembled a solid body. Till then he only considered it as a flat surface, vriously shadowed; but when he began to perceive that these kind of shadings actually represented human beings, he then began to examine by his touch whether they had not the usual qualities of such bodies, and was greatly surprised to find what he expected a very unequal surface to be smooth and even. He was then shown a miniature picture of his father, which was contained in his mother's watch-case, and he readily perceived the resemblance; but asked with great astonishment how so large a face could be contained in so small a compass. It seemed as strange to him as if a bushel was contained in a pint vessel. At first he could bear but a very small quantity of light, and he saw every object much greater than the life; but, in proportion as he saw objects that were really large, he seemed to think the former were diminished; and although he knew the chamber where he was contained in the house, yet until he saw the latter he could not be brought to conceive how a house could be larger than a chamber. Before the operation he had no great expectations from the pleasure he should receive from a new sense; he was only excited by the hopes of being able to read and write; he said, for instance, that he could have no greater pleasure in walking in the garden with his sight than he had without it, for he walked there at his ease, and was ac quainted with all the walks. He remarked, also with great justice, that his former blindness gave him one advantage over the rest of mankind, which was that of being able to walk in the night with confidence and security. But when he began to make use of his new sense he seemed transported beyond measure. He said that every new object was a new source of delight, and that his pleasure was so great as to be past expression. About a year after this he was brought to Epsom, where there is a very fine prospect, with which he seemed greatly charmed; and he called the landscape before him a new method of seeing. He was couched in the other eye a year after the former, and the operation succeeded remarkably well. When he saw with both eyes, he said that objects appeared to him twice as large as when he saw but with one; however, he did not see them doubled, or at least he showed no signs as if he saw them so. Mr. Cheselden mentions instances of many more that were restored to sight in this manner; they all seemed to concur in their perceptions with this youth, and they all seemed particularly embarrassed in learning how to direct their eyes to the objects they wished to observe.

In this manner it is that our feeling corrects the sense of seeing, and that objects which appear of very different sizes at different distances are all reduced by experience to their natural standard. But not the feeling only, but

also the colour and brightness of the object, contribute in some measure to assist us in forming an idea of the distance at which it appears. Those which we see most strongly marked with light and shade we readily know to be nearer than those on which the colours are more faintly spread, and that in some measure take a part of their hue from the air between us and them. Bright objects, also, are seen at a greater distance than such as are obscure, and most probably for this reason-that, being less similar in colour to the air that interposes, their impressions are less effaced by it, and they continue more distinctly visible. Thus a black and distant object is not seen so far off as a bright and glittering one, and a fire by night is seen much farther off than by day. The power of seeing objects at a distance is seldom equal in both eyes. Wheu this inequality is in any great degree, the person so circumstanced then makes use only of one eye, shutting that which sees the least, and employing the other with all its power. And hence proceeds that awkward look which is known by the name of" strabism."

There are many reasons to induce us to think that such as are near-sighted see objects larger than other persons; and yet the contrary is most certainly true, for they see them less. Mr. Buffon informs us that he him self was short-sighted, and that his left eye was stronger than his right. He has very frequently experienced upon looking at an object, such as the letters of a book, that they appear less to the weakest eye; and that when he placed the book so as that the letters appeared double, the images of the left eye, which was strongest, were larger than those of the right, which was more feeble. He has examined several others who were in similar circumstances, and has always found that the best eye saw every object the largest. This he ascribes to habit; for near-sighted people being accustomed to come close to the object, and view but a small part of it at a time, the habit ensues, when the whole of an object is seen, and it appears less to them than to others.

Infants, having their eyes less than adults, must see objects also smaller in proportion; for the image formed on the back of the eye will be large as the eye is capa cious; and infants, having it not so great, cannot have so large a picture of the object. This may be a reason also why they are unable to see so distinctly or at such distances as persons arrived at maturity.

Old men, on the contrary, see bodies close to them very indistinctly, but bodies at a great distance from them with more precision; and this may happen from an alteration in the coats or humours of the eye, and not, as is supposed, from their diminution. The cornea, for instance, may become too rigid to adapt itself, and take a proper convexity for seeing minute objects; and its very flatness will be sufficient to fit it for distant vision.

When we cast our eyes upon an object extremely brilliant, or when we fix and detain them too long upon the same object, the organ is hurt and fatigued, its vision becomes indistinct, and the image of the body, which has thus too violently or too perseveringly employed us, is painted upon everything we look at, and mixes with every object that occurs. And this is an obvious consequence of the eye taking in too much light, either immediately or by reflection. Every body exposed to the light for a time drinks in a quantity of its rays, which, being brought into darkness, it cannot instantly discharge. Thus the hand, if it be exposed to broad day-light for some time, and then immediately snatched into a dark roof, will appear still luminous; and it will be some time before it is totally darkened. It is thus with the eye, which, either by an instant gaze at the meridian sun or a steady continuance upon some less brilliant object, has taken in too much light; its humours are for a while unfit for vision, until that be discharged and room made for rays of a milder nature.

How dangerous the looking upon bright and luminous objects is to the sight, may be easily seen from such as live in countries covered for most part of the year with snow, who become generally blind before their time. Travellers who cross these countries are obliged to wear a crape to save their eyes, which would otherwise be rendered totally unserviceable; and it is equally dangerous in the sandy plains of Africa. The reflection of the light is there so strong, that it is impossible to sustain the effect without incurring the danger of losing one's sight entirely. Such persons, therefore, as read or write for any continuance should choose a moderate light, in order to save their eyes; and although it may seem sufficient at first, the eye will accustom itself to the shade by degrees, and be less hurt by the want of light than the excess.

It is indeed surprising how far the eye can accommodate itself to darkness, and make the best of a gloomy situation. When first taken from the light and brought into a dark room, all things disappear; or, if anything is seen, it is only the remaining radiations that still continue in the eye. But after a very little time, when these are spent, the eye takes advantage of the smallest ray that happens to enter; and this alone would in time serve for many of the purposes of life. There was a gentleman of great courage and understanding, who was a major under King Charles I. This unfortunate man, sharing in his master's misfortunes, and being forced abroad, ventured at Madrid to do his king_a signal service, but unluckily failed in the attempt. In consequence of this he was instantly ordered to a dark and dismal dungeon, into which the light never entered, and into which there was no opening but by a hole at the top, down which the keeper put his provisions, and presently closed it again on the other side. In this manner the unfortunate loyalist continued for some weeks, distressed and disconsolate; but at last he began to think he saw some little glimmering of light. This internal dawn seemed to increase from time to time, so that he could not only discover the parts of his bed and such other large objects, but at length he even began to perceive the mice that frequented his cell, and saw them as they ran about the floor eating the crumbs of bread that happened to fall. After some months' confinement he was at last set free; but such was the effect of the darkness upon him that he could not for some days venture to leave his dungeon, but was obliged to accustom himself by degrees to the light of the day.

CHAP. VIII.

OF HEARING.

As the sense of hearing as well as of sight gives us notice of remote objects, so like that it is subject to similar errors, being capable of imposing on us upon all occasions where he cannot rectify it by the sense of feeling. We can have from it no distinct intelligence of the distance from whence a sounding body is heard; a great noise far off and a small one very near produce the same sensation; and, unless we receive information from some other sense, we can never distinctly tell whether the sound be a great or a small one. It is not till we have learned by experience that the particular sound which is heard is of a peculiar kind; then we can judge of the distance from whence we hear it. When we know the tone of the bell, we can then judge how far it is from us.

Every body that strikes against another produces a sound, which is simple, and but one in bodies which are not elastic, but which is often repeated in such as are. If we strike a bell or a stretched string, for instance, which are both elastic, a single blow produces a sound,

which is repeated by the undulations of the sonorous body, and which is multiplied as often as it happens to undulate or vibrate. These undulations each strike their own peculiar blow; but they succeed so fast, one behind the other, that the ear supposes them one continued sound; whereas in reality they make many. A person who should for the first time hear the toll of a bell, would very probably be able to distinguish these breaks of sound; and, in fact, we ourselves can readily perceive an intension and remission in the sound.

In this manner, sounding bodies are of two kinds; those unelastic ones, which, being struck, return but a single sound; and those more elastic, returning a succession of sound, which, uniting together, form a tone. This tone may be considered as a great number of sounds all produced one after the other by the same body, as we find in a bell or the string of a harpsichord, which continues to sound for some time after it is struck. A continuing tone may be also produced from a nonelastic body by repeating the blow quick and often, as when we beat a drum, or when we draw a bow along the strings of a fiddle.

Considering the subject in this light, if we should multiply the number of blows, or repeat them at quicker intervals upon the sounding body, as upon the drum, for instance, it is evident that this will have no effect in altering the tone; it will only make it either more even or more distinct. But it is otherwise if we increase the force of the blow; if we strike the body with double weight this will produce a tone twice as loud as the former. If, for instance, I strike a table with a switch, this will be very different from the sound produced by striking it with a cudgel. Hence, therefore, we may infer that all bodies give a louder and graver tone, not in proportion to the number of times they are struck, but in proportion to the force that strikes them. And if this be so, those philosophers who make the tone of a sonorous body-of a bell or the string of a harpsichord, for instance-to depend upon the number only of its vibrations and not on the force, have mistaken what is only an effect for a cause. A bell or an elastic string can only be considered as a drum beaten; and the frequency of the blows can make no alteration whatever in the tone. The largest bells and the longest and thickest strings have the most forceful vibrations; and therefore their tones are the most loud and the most grave.

To know the manner in which sounds thus produced become pleasing, it must be observed, no one continuing tone, how loud or swelling soever, can give us satisfaction: we must have a succession of them, and those in the most pleasing proportion. The nature of this proportion may be thus conceived. If we strike a body incapable of vibration with a double force, or, what amounts to the same thing, with a double mass of matter, it will produce a sound that will be doubly grave. Music has been said by the ancients to have been first invented from the blows of different hammers on an anvil Suppose, then, we strike on an anvil with a hammer of one pound weight, and again with a hammer of two pounds, it is plain that the two-pound hammer will produce a sound twice as grave as the former. But if we strike with a two-pound hammer and then with a three-pound, it is evident that the latter will produce a sound one-third more grave than the former. If we strike the anvil with a three-pound hammer and then with a four-pound, it will likewise follow that the latter will be a quarter part more grave than the former. Now, in the comparing between all these sounds, it is obvious that the difference between one and two is more easily perceived than between two and three, three and four, or any numbers succeeding in the same proportion. The succession of sounds will be therefore pleasing in proportion to the ease with which they may be distinguished. That sound which is double the former, or, in other words, the octave to the preceding tone, will of all others be the most

pleasing harmony. The next to that, which is as two to three, or, in other words, the third, will be most agreeable. And thus, universally, those sounds whose difference may be most easily compared are the most agreeable. Musicians, therefore, have contented themselves with seven different proportions of sound, which are called "notes," and which sufficiently answer all the purposes of pleasure. Not but that they might adopt a greater diversity of proportions; and some have actually done so; but in these the differences of the proportion are so imperceptible, that the ear is more fatigued than pleased in making the distinction. In order, however, to give variety, they have admitted half-tones; but in all the countries where music is yet in its infancy they have rejected such; and they can find music in none but the obvious ones, The Chinese, for instance, have neither flats nor sharps in their music; but the intervals between their other notes are in the same proportion with ours.

Many more barbarous nations have their peculiar instruments of music; and what is remarkable, the proportion between their notes is in all the same as in ours. This is not the place for entering into the nature of these sounds, their effects upon the air, or their consonances with each other. We are not now giving a history of sound, but of human perception.

All countries are pleased with music; and if they have not skill enough to produce harmony, at least they seem willing to substitute noise. Without all question, noise alone is sufficient to operate powerfully on the spirits; and, if the mind be already predisposed to joy, I have seldom found noise fail of increasing it into rapture. The mind feels a kind of distracted pleasure in such powerful sounds, braces up every nerve, and riots in the excess. But, as in the eye an immediate gaze upon the sun will disturb the organ, so in the ear a loud, unexpected noise disorders the whole frame, and sometimes disturbs the sense ever after. The mind must have time to prepare for the expected shock, and to give its organs the proper tension for its arrival.

Musical sounds, however, seem of a different kind. Those are generally most pleasing which are most unex pected. It is not from bracing up the nerves, but from the grateful succession of the sounds, that these become so charming. There are few, how indifferent soever, but have at times felt their pleasing impression; and perhaps even those who have stood out against the powerful persuasion of sounds only wanted the proper tune or the proper instrument to allure them.

The ancients give us a thousand strange instances of the effects of music upon men and animals. The story of Arion's harp, that attracted the dolphins to the ship's side, is well known; and what is remarkable, Schotteus assures us that he saw a similar instance of fishes being allured by music. They tell us of diseases that have been cured, unchastity corrected, seditions quelled, passions removed, and sometimes excited even to madness. Dr. Wallis has endeavoured to account for these surprising effects by ascribing them to the novelty of the art. For my own part, I can scarce hesitate to impute them to the exaggeration of their writers. They are as hyperbolical in the effects of their oratory; and yet we well know there is nothing in the orations they have left us capable of exciting madness, or of raising the mind to that ungovernable degree of fury which they describe. As they have exaggerated, therefore, in one instance, we may naturally suppose that they have done the same in the other; and, indeed, from the few remains we have of their music, collected by Meibomius, one might be apt to suppose there was nothing very powerful in what is lost. Nor does any one of the ancient instruments such as we see them represented in statues appear comparable to our fiddle.

However this be, we have many odd accounts, not only among them but also among the moderns, of the