CLEARNESS

-QUALITY-DIRECTION.

209

monies I should have to speak at length if I were discussing the Emotions of Art in general.

11. Clearness, or purity.-A clear sound is one that has a distinct, uniform character, and is not choked or encumbered with confusing ingredients. Clearness is a property that affects both the perception of meaning and the pleasure of music. A clear-toned instrument is one that yields, unmixed and in perfection, the notes that the performer aims at producing. The perception of tone or pitch must needs depend very much on the clearness of the sound. In instruments, the purity varies with the substance. Silver, among the metals, is clear-toned. Glass, from the uniformity of its texture, is noted for this quality. In instruments of wood, a hard and uniform tissue is indispensable. In the human voice musical clearness and articulate clearness depend upon totally different qualities. The first arises from the structure of the larynx and the molecular nature of the resonant skull; the second depends upon the sharpness and suddenness of the articulate actions of the mouth. In every kind of expression clearness is a cardinal virtue; the merit of musical or articulate performances must rise or fall according as the effect intended stands out apart from other effects not intended.

12. Quality (Intellectual or Discriminative).—This relates to the feeling of difference, that difference of material gives, whereby we discriminate between one substance and another, as in the ring of a shilling or a sovereign, and in the difference already alluded to between one person's voice and another. This discriminativeness of the ear, corresponding to a distinctiveness of sonorous quality in bodies, is of the greatest consequence in our daily operations.

13. Direction. This is a purely intellectual sensation, in other words, is of importance as leading us to perceive the situation of the objects of the outer world whence the sound takes its rise.

Some have supposed that the labyrinthine apparatus is intended to give us the perception of distance at once and independent of experience. This view has been put forth by Professor Wheatstone. But so far as I can judge of the

P

matter, I prefer the explanation that refers this perception entirely to experience. The following extract from Longet expresses what I mean :—

'With regard to the direction of the sonorous waves we can at present only say, that the knowledge of it is owing to a process of reasoning applied to the sensation. Thus, we hear distinctly a sound emanating from a given point, whatever be the position of the head; but the ear being able to judge of slight differences in the intensity of sounds, we remark that, in certain positions of the head, the sound seems stronger. We are hence led to place our head in one fixed position as regards the sounding body. But our sight tells what is this direction of most perfect hearing; and we then apply the observation made on bodies that we can see to those that are not seen.'

The sense of direction is by no means very delicate, even after being educated to the full. We can readily judge whether a voice be before or behind, right or left, up or down; but if we were to stand opposite to a row of persons, at a distance, say, of ten feet, we should not be able, I apprehend, to say which one emitted a sound. This confusion is well known to schoolmasters. So it is next to impossible to find out a skylark in the air from the sound of its song.

The combined action of the two ears undoubtedly favours the perception of direction of sound very materially. A person who has lost the hearing on one side, is usually unable to say whether a sound is before or behind. The change of effect produced by a slight rotation of the head, is such as to indicate direction to the mind. For while the sound becomes more perceptible on one ear, the ear turned to face the object more directly,-the sound in the other ear is to the same degree obscured. When the head is so placed, after various trials, that the greatest force of sensation is felt on the right ear, and the least on the left, we then infer that the sounding body is away to the right; when the two effects are equal, and when any movement of the head makes them unequal, we judge the sound to be either right in front, or

DISTANCE-ARTICULATE FORM.

211

behind; and we can further discriminate so as to determine between these two suppositions.

14. The perception of distance can result from nothing but experience. I quote again from Longet. As soon as the organ presents a sensibility and a development sufficient for discerning easily the relative intensity of two consecutive sounds, nothing farther is necessary in order to acquire the notions of distance and direction of the body from which the sonorous waves emanate. In fact, if a sound is already known to us, as in the case of the human voice, or an instrument, we judge of its distance by the feebleness of its impression upon the nerve of hearing; if the sound is one whose intensity, at a given distance, is unknown, as, for example, thunder, we suppose it nearer according as it is louder.'

15. Articulate form.-This quality relates almost exclusively to the effect produced by the sounds issuing from the human voice, as modified by the shape of the mouth during their utterance. By widening the mouth during the emission of sound a broad vowel, ah, is sounded; and we have a very distinct feeling of the difference between this sound and the sound issuing from a contracted mouth, as in the vowel u of 'put.' Whether this difference is due solely to the greater area or expansion of the stream of sound in one case, I cannot pretend to say; but it is probable that this must be looked upon as a leading circumstance. We have already seen that sounds affect us differently according to their volume, or the extent of sounding surface; and the present case may repose in part upon this distinction. When a number of sounds proceed together to the ear, we may have every variety of perception according as the individual sounds are varied; thus there is something articulate in the uproar of a multitude. from the waving of the sound to and fro, now from one corner, now from another, and again from the whole in chorus. When a vowel sound emanates from the mouth, the thickness and shape of the column of sound are modified, and this modification has a characteristic influence upon the ear, owing to the distinction felt between a wide and narrow origin of

sound. So much as regards the vowels. In the consonants, the discrimination must hinge upon something different from the area and shape of the stream as diffused from the mouth. It is easy to understand the difference of the labials or dentals according as they are mute or vocal, the difference between p and b, or between t and d; what is to be explained is the difference in the mutes, namely, p, t, k, which are produced by the abrupt opening or closure of the lips, the teeth, and the throat respectively, these two last being closed by the tongue; the difference in short between the articulations ap, at, ak. The question is, what is the peculiarity in the formation of those sounds that makes them felt as different to every ear? We must confess that there is no adequate reply to this question; there appears to me to be somewhat of the same obscurity here as in the timbre or quality of sound issuing from different substances or voices. It seems at first sight not more wonderful that we should discriminate between labial, dental, and guttural sounds, than that we should discriminate between one man's articulation and another; but the difficulty is not the same. It is likely that the difference lies in the mode of formation of the sound by the stroke of the parts: in the lips the blow seems softer and less abrupt, in the back part of the palate it is much harder; there we can produce a sharp click that could not be made to arise between two soft substances like the lips. Whether or not some other permanent difference holds between those sounds arising from the difference of locality of the opening and closure, I will not endeavour to decide.

Some people are distinguished by their susceptibility to articulate sounds, a kind of susceptibility or discrimination that makes an ear for language, as the discrimination of pitch makes a musical ear. There appears to be no necessary connexion between the two gifts, and experience shows that one may exist in a high degree along with deficiency in the other. At the same time, I believe that a good ear will for the most part be good for all the points of hearing. The sense of pitch is probably the least bound up with other sensibilities.

As a general rule, the emotional sensibility of any sense

bears no relation to the intellectual sensibility. An ear may be very inflammable to exciting effects of sound, and may at the same time be very dull to all those differences of quality and degree that constitute the meaning of sounds as well as their delicate harmonies. It is like the difference to the eye between a bonfire and a landscape, between the glare of noon and an algebraical formula.

16. The duration of an impression of sound can be appreciated by noting at what intervals a succession of beats seems an uninterrupted stream of sound. This makes, in fact, the inferior limit of the audibility of sounds. From the experiments of Savart, it would appear that a series of beats begins to be felt as continuous when they number from ten to twelve in a second; so that the impression of each must continue not less than the tenth part of a second.

SENSE OF SIGHT.

1. The objects of sight include nearly all material bodies. Their visibility depends on their being acted on by Light, the most inscrutable of natural agents. Certain bodies, such as the Sun, the Stars, flame, solids at a high temperature, give origin to rays of light, and are called self-luminous. Other bodies, as the Moon, Planets, and the greater number of terrestrial surfaces, are visible only by reflecting the rays they receive from the self-luminous class.

The reflection of light is of two sorts: mirror reflection, which merely reveals the body that the light comes from; and reflection of visibility, which pictures the reflecting surface. In this last mode of reflection the light is broken up and emitted in all directions exactly as from a self-luminous original. Visible surfaces receiving light from the sun have thus the power of absorbing and reissuing it, while a mirror simply gives a new direction to the rays. When we look at a picture in a bad light, we find that the rays of reflection overpower the rays arising from the coloured surface of the picture, and consequently the picture is imperfectly seen.

As regards vision, bodies are either opaque or transparent.