or amount of movement gone over should be a matter of distinct perception through the sensibility to the amount of force expended in time, the degree of effort being the same. The sensibility now in question differs from the former chiefly in making the degree turn upon duration, and not upon the amount expended each instant; and it seems to me impossible to deny that force increased or diminished simply as regards continuance, is as much a subject of discriminative sensibility as force increased or diminished in the intensity of the sustained effort.

It is in the special senses of touch and sight, or rather in the muscular sensibility united with those senses, that the feeling of range is most conspicuously manifested. When instead of swinging the arm in empty space, we draw the hand over the surface of a table, the sense of range is made more distinct by the prolongation of the rubbing contact. So with sight, as we shall show in the proper place. But in the meantime, it is necessary to recognise an independent sensibility of muscle to this attribute of range, for without such inherent sensibility the addition of a sensation of special sense would not suffice to give birth to the discrimination we are now contending for.

26. If the sense of degrees of range be thus admitted as a genuine muscular discrimination, its functions in outward perception are very important. The attributes of extension and space fall under its scope. In the first place, it gives the feeling of linear extension, inasmuch as this is measured by the sweep of a limb, or other organ moved by muscles. The difference between six inches and eighteen inches is expressed to us by the different degrees of contraction of some one group of muscles; those, for example, that flex the arm, or in walking, those that flex or extend the lower limb. The inward impression corresponding to the outward fact of six inches in length, is an impression arising from the continued shortening of a muscle, a true muscular sensibility. It is the impression of a muscular effort having a certain continuance; a greater length produces a greater continuance (or a more

DISCRIMINATION OF DEGREES OF EXTENSION. 115

rapid movement), and in consequence an increased feeling of expended power.

The discrimination of length in any one direction includes extension in every direction. Whether it be length, breadth, or height, the perception has precisely the same character. Hence superficial and solid dimensions, the size or magnitude of a solid object, come to be felt in a similar manner. But we shall defer the consideration of this attribute till we come to speak of the senses, more especially Touch and Sight.

It will be obvious that what is called situation or Locality must come under the same head, as these are measured by distance taken along with direction; direction being itself estimated by distance, both in common observation and in mathematical theory. In like manner, form or shape is ascertained through the same primitive sensibility to extension or range.

By the muscular sensibility thus associated with prolonged contraction we can therefore compare different degrees of the attribute of space, in other words, difference of length, surface, situation, and form. When comparing two different lengths we can feel which is the greater, just as in comparing two different weights or resistances. We can also, as in the case of weight, acquire some absolute standard of comparison, through the permanency of impressions sufficiently often repeated. We can engrain the feeling of contraction of the muscles of the lower limb due to a pace of thirty inches, and can say that some one given pace is less or more than this amount. According to the delicacy of the muscular tissue we can, by shorter or longer practice, acquire distinct impressions for every standard dimension, and can decide at once as to whether a given length is four inches or four and a half, nine or ten, twenty or twenty-one. This sensibility to size, enabling us to dispense with the use of measures of length, is an acquirement suited to many mechanical operations. In drawing, painting, and engraving, and in the plastic arts, the engrained discrimination of the most delicate differences is an indispensable qualification.

27. The third attribute of muscular discrimination is the velocity or speed of the movement. It is difficult to separate this from the foregoing. In the feeling of range, velocity answers the same purpose as continuance; both imply an enhancement of effort, or of expended power, different in its nature from the increase of dead effort in one fixed situation. We must learn to feel that a slow motion for a long time is the same as a quicker movement with less duration; which we can easily do by seeing that they both produce the same effect in exhausting the full range of a limb. If we experiment upon the different ways of accomplishing a total sweep of the arm, we shall find that slow movements long continued are equal to quick motions of short continuance, and we are thus able by either course to acquire to ourselves a measure of range and lineal extension.

We have already seen that there is a characteristic difference between effort expended in movement and effort expended in dead resistance: the one is more keen, fiery, and exciting than the other. This peculiar exciting character seems to us as the means of discriminating the two kinds of effort, and also helps to discriminate the degrees or pace of movement; a more rapid action produces a different mode of excitement from one less rapid. This is to us a measure of speed, which, as well as continuance, is a measure of extension, or space moved over. Whether we fasten upon the slow movement with long continuance, or the quick movement with short continuance, we get a characteristic and peculiar sensibility different for every amount of length, and serving as our estimate and impression of such amount. But besides using velocity as a means of measuring length, we require it as a measure of itself, that is to say, we are often called upon to judge of the different velocities of moving bodies; our own speed in walking, for example, or the rate of any object moving past us. We can not only compare two different velocities tried in succession, but we can also acquire, as with weight and size, the engrained impression of some standard velocity, wherewith to compare any case that occurs.

28. We would thus trace the perception of the mathe

PERCEPTIONS DUE TO MUSCULAR SENSIBILITY.

117

matical and mechanical properties of matter to the muscular sensibility alone. We admit that this perception is by no means very accurate if we exclude the special senses, but we are bound to show at the outset that these senses are not essential to the perception, as we shall afterwards show that it is to the muscular apparatus associated with the senses that their more exalted sensibility must be also ascribed. The space moved through by the foot in pacing may be appreciated solely through the muscles of the limb, as well as by the movements of the touching hand or the seeing eye. Whence we may accede to the assertion sometimes made, that the properties of space might be conceived, or felt, in the absence of an external world, or of any other matter than that composing the body of the percipient being; for the body's own movements in empty space would suffice to make the very same impressions on the mind as the movements excited by outward objects. A perception of length, or height, or speed, is the mental impression, or state of consciousness, accompanying some mode of muscular movement, and this movement may be generated from within as well as from without; in both cases the state of consciousness is exactly the same.

We have thus gone over the three great classes of muscular feelings enumerated at the outset of the chapter. Other forms of muscular sensibility will arise in the course of our exposition, through the combinations with other kinds of consciousWe have not exhausted all that requires to be said on the sense of effort* accompanying muscular exercise, which

ness.

Sir William Hamilton, in his Dissertations on Reid, p. 864, has drawn a distinction between what he calls the locomotive faculty,' and the muscular sense, maintaining that the feeling of resistance, energy, power, is due to the first and not to the second. By this locomotive faculty he means the feeling of volitional effort, or of the amount of force given forth in a voluntary action; while he reduces the application of the term muscular sense, to the passive feeling that he supposes us to have of the state of tension of the muscle.

His words are: 'It is impossible that the state of muscular feeling can enable us to be immediately cognizant of the existence and degree of a resisting force. On the contrary, supposing all muscular feeling abolished, the power of moving the muscles at will remaining, I hold that the consciousness of the mental motive energy, and of the greater or less intensity

distinguishes the voluntary from the involuntary actions. I must likewise postpone the discussion of the feelings of selfconfidence and self-satisfaction, and of self generally, which manifest themselves in the course of active exertion. Moreover, much yet remains to be said on the connexion of muscular sensibility with the processes of intelligence.

of such energy requisite, in different circumstances, to accomplish our intention, would of itself enable us always to perceive the fact, and in some degree to measure the amount, of any resistance to our voluntary movements; howbeit the concomitance of certain feelings with the different states of muscular tension, renders this cognition not only easier, but, in fact, obtrudes it on our attention.'

The difficulty that I feel, with reference to this distinction, is to recognise any muscular sense remaining after the feeling of expended energy is subtracted. I know of no fact that would suffice to substantiate Sir W. Hamilton's assumption, that we have a feeling of the state of tension of a muscle, independently of our feeling of motive power put forth. It may be quite true that sensitive nerve filaments are supplied to the muscles as well as motor filaments, and that through these we are affected by the organic condition of the tissue, as in the first class of feelings above described; but it does not follow that we obtain by the same filaments a distinctive feeling of the degree of the muscle's contraction.

The sense of expended energy I take to be the great characteristic of the muscular consciousness, distinguishing it from every mode of passive sensation. By the discriminative feeling that we possess of the degree and continuance of this energy, we recognise the difference between a greater and a less stretch of muscular tension, and no other sensibility seems to me to be called for in the case.

I may here express the obligations we are under to Sir William Hamilton for his historical sketch of the doctrine of the Muscular Sense contained in the same note; which is not the least valuable and interesting of his many contributions to the history of mental and metaphysical

science.