yields to the muscular force with which the finger is pressed upon it, we estimate this quality by the degree of force employed. If the body yields, but recovers its shape when the finger is removed, we call this elasticity, a fact, however, made known to Eventuality. Degrees of what is called softness, when within the estimating power of muscular force, are ascertained by causing muscular force to act upon the body in two opposite directions; by pressing it between the finger and thumb, for example. Here we have the same organ directing the finger and thumb, so that we experience the same effect as in touching a body with one finger. Or, if we simply connect the finger and thumb, the sense of touch or resistance, and the estimating faculty of force, are both active without the intervention of an external body.

Shape or form, in solid bodies, is discovered by forces resisting in different directions. And here the notion of a faculty for cognizing direction occurs; and this is that of locality or relative position. The external senses administer to all the facul ties; and as there are but five external instruments of sense, the skin, the eye, the nose, the ear, and the tongue, I consider this as a fixed and immutable argument against the existence of any greater number of senses, properly so called. Perhaps Mr Simpson may have confounded perception exercised by the faculties which have their organs in the cerebrum with external sense. We are very apt to do this, and probably it has been the cause of the prolonged discussion, which, however, has not been without its use.

It may be asked, what are the forces the exertion of which constitutes that which is cognized by means of the sense of Touch? Perhaps their enumeration, with some remarks, may assist in settling the question at issue. Suppose we see before us a statue; or suppose (a thing I should not advise on every occasion) that we shut our eyes in proceeding to the investigation, and trust entirely to the sense of touch. When we experience resistance, we discover, by means of our hands, the degree of hardness and smoothness by the simple exertion of muscular force. We discover the form or shape by the variety of the direction in which the resisting force meets our muscular force relatively to our own position, and of the position of the parts relatively to each other, the faculties of Locality and of Form being called into activity. If we now wish to acquire knowledge of the nature of the material of which the statue is made, we first discover that it does not yield to the pressure of the finger. We try more force by interposing the nail of the finger. If it does not resist this, then we conclude that the statue is made of wood or of lead. We have the means, however (supposing that we have had some previous experience),

matter.

to determine this point, by calling in the aid of another sense, which shall address Eventuality. We tap the statue in a manner to elicit sound, and the quality of the sound determines the But we may determine this point by employing force. We may set our shoulders to the statue, and if it be not fixed by any other force than its own gravity or weight, we can ascertain whether it be of a light material like wood, or of a heavy one like lead. Lead would be distinguished from bronze by a sound produced by tapping with the nail or some hard substance taken into the hand, through which intervening substance resisting force is communicated. Natural philosophers perhaps err when they speak of the communication of motion, instead of the communication of force; motion being the effect of one force overcoming another or other forces. In the present case, we estimate the force of the adhesion of the particles of the substance of which the statue is made, and then the density. If we overturn the statue, we overcome its gravitating force. If we break it, we find that it is fixed by some other substance, such as an iron bolt at the base, which has a stronger adhesive force than the material of the statue.

The first time a person saw a piece of cork, he might, when desirous to ascertain its qualities, use far more force than was necessary to move it, and drive it to a distance. Next time he touches it, the faculty of force directs him to use very little. He finds that so little resistive power is inherent in the cork, that he takes it up in one hand, and supplies it with as much additional force as will enable him to proceed in his examination by means of his other hand.

I said that force is constant. Where, in what department of nature, is it not in continual unceasing action? Resistance is only a mode of force in reference to ourselves, and to bodies among each other. Resistance is not constant to our fingers, in reference to our perceptions, though it be so in reality for the pressure of the atmosphere is upon us constantly. I used the word constant solely in reference to perception. In this I may have erred. But granting constant resistance to Mr Simpson, it is nothing in reality but a constant force, acting in a particular mode and direction in reference to some other force; so that, probably, the error may be mutual, since resistance and touch appear to be the same sense, the one term defining the other. If Mr Simpson had pointed out any perception which he can derive from a sense called touch, which had no connection whatever with force, then I might yield to his sixth sense. But until he completes such a demonstration, I must remain in my present opinion that the sixth sense is unconnected with resistance.

In all the circumstances of external bodies in reference to our VOL. IX.NO. XLIV.

selves which have been enumerated, supposing our eyes shut, we have no experience till contact is made, and then we estimate force. If Mr Simpson makes a false step in the dark, the shock at once leads him to the estimate of the force with which she moved, and of the force with which he was opposed. The instant his foot comes into contact with the obstacle, or, in other words, touches it, he begins to estimate force. He never thinks of the common thing touch extending beyond a very slight degree of force; nay, he regards a small degree of force as something different. This error misled me also, more perhaps than my ignorance of the fact of two nerves being in one sheath. On that fact I reason differently. On one point, that one of the nerves is that which discharges the office of muscular contraction and relaxation, Mr Simpson and I are at one. But the other nerve is that of the well known sense touch, and which I certainly should prefer to name resistance, because touch implies merely the circumstance of contact, whereas resistance is generally understood as a word connected with and implying force; and it is the office of the nerve to make the faculty of force aware of opposing force. I can discover nothing connected with the vulgar notion of touch, but degrees of force made known to us as external. If Mr Simpson can discover any thing else, I shall be much beholden to him. At present, I am disposed not to abandon the word touch, but to retain it in the understanding that it is the sense by which the presence to us of external force is conveyed to the organ and faculty of force specially, and to other faculties, to enable them to determine certain qualities of external things. The word resistance conveys at once all this definition. But as a definition may be wanted at any rate, it may be as well to be in no haste to change the conventional term.

Mr Simpson has accused me of having abandoned my first love Resistance. I am certainly obliged to him for having taken her under his protection; otherwise it is probable her veil might not have been lifted up so as to discover to me so very old an acquaintance as Touch. I do not yet see that my error was so very great as to prevent my seeing all the truth. I saw two things, and the puzzle was, what were they? I was aware that the sense of touch conveyed the sensation of resistance; and now I see, or at least think I see, the whole matter clearly, and that the faculty is that of force, having its organ in that part of the cerebrum formerly marked Weight, connected by means of nerves with the instruments of sense. I might wait, then, for Mr Simpson's demonstration, that the sense commonly called touch has other functions than to cognise force, and by that means to enable the mind to ascertain certain qualities of bodies. But without arrogating to myself any thing like the merit of a

discovery, I beg to submit to you whether we should not determine on a sixth sense, to which I propose to apply a term in common use, and of which the skin is also the organ. The sensations of Heat, Cold, Pain, Itching, &c. in all their degrees and varieties, have hitherto been assigned to the province of touch. We have now ample reason, if we chuse, for limiting the term touch to forces; and the name of the sixth sense I propose should be FEELING, if we are to have one. This term has been in common use, and been assumed as synonymous with touch. It appears now to be probable that physiologists may hereafter find the complete separation of the two terms useful; and it may be so in ordinary discourse.

Before concluding, allow me to remark on the extraordinary economy observed in the structure of our bodies, an economy which weighs strongly against the farther multiplication of senses, without good cause shewn. Taking the instrument of the sense of Touch, as heretofore understood, and which I have shewn reason for believing to be the instrument of more than one, this single instrument conveys to us ideas of Force in all its varieties, and of Form, and of all the causes of resistance to force, which are so many distinct qualities of external objects,-of heat, cold, &c. The tongue conveys perception of Taste; but it also is capable of enabling us to distinguish forces, and form to a certain extent. It also assists in deglutition and swallowing. It regulates the tones of the voice, by enlarging or diminishing the capacity of the fauces; and the instinctive rapidity with which it obeys the will, so as to produce precisely the tone desired, is truly astonishing. The functions of the nose are more limited; yet it is contrived to secure breathing, should the passage by the mouth be closed, and serves as a passage for the expulsion of useless excreted matter. The ear warns us of the

presence of moving bodies, and, by a comparison of the qualities and intensities of sound, it informs of the distance from which sound proceeds, and of the nature of the thing which produces it; and all this exclusive of the pleasures of music. The eye conveys to us the perception of light, and its absence,-of form, colour, position, distance, height, depth, bulk, motion, rest, smoothness, roughness, transparency, opacity, &c. Now, although the skin be the instrument of many things that might be called senses, we speak only of one sense belonging to it, calling it Touch, which, as has been shewn, gives, by means of contact and forces, a knowledge of the presence and qualities of a great variety of external objects. Heat and cold may be merely qualities of some form of matter made known to us by its impinging, with a force insensible to resistance, on the skin, over which nervous fibres are spread to convey this and many other perceptions. We cannot appreciate the force of heat any more

than that of light. But that they move, and that their movement implies force, however minute in degree, is obvious; and we recur to resistance: and thus I may be forced once more to embrace my First Love, as Mr Simpson good-humouredly calls it, but not as a faculty, in which character I abandoned her, but as a sense, and an old acquaintance under a new name, who seems to say, Noli me tangere. We must take care of such jade's tricks.

I firmly believe that there is a distinct nervous fibre for every distinct impression which we receive from external nature, through the fine instruments called those of the senses; but it would be endless to attempt analyzing and giving naines to them all. It is also my belief, that, in every organ of the brain, there are parts innumerable, each destined to give to the mind special information, and to enable it to operate in a special manner on special subjects. But it would be useless, probably, to attempt giving names to each. It is better to retain a few terms, and to understand what they include. On this principle, the term Touch may still be retained, and both Resistance and Feeling left as they were. I am, &c. G. S. MACKENZIE.

[We refrain at present from expressing any opinion upon the question at issue between Sir George Mackenzie and Mr Simpson, in the hope that some of our medical readers will be kind enough to communicate such illustrative pathological cases as they happen to be acquainted with. Instances of loss of sensibility to heat, cold, pain, and tickling, without impairment of the power of voluntary motion,--and vice versa,-are sufficiently numerous, and do not bear on the present question: what we want are cases of patients who, on coming into contact with unseen solid bodies, are made aware of this contact either by the perception of resistance alone, or solely by the sensation of heat, cold, pain, tickling, or some other analogous feeling not resolvable into the sense of resistance. We have little doubt that cases of this nature are not uncommon.—ED.]

ARTICLE X.

CEREBRAL DEVELOPMENT AND INFERRED CHARACTER OF KABOOTI, AN EGYPTIAN MUMMY, presented to the Belfast Museum, by THOMAS GREG, Esq. of Ballymenoch, county of Down. Read at a Meeting of the Belfast Natural History Society, 4th March 1835, by Mr ROBERT PATTERSON, Vice-President.

THIS mummy was unrolled on the 27th of January 1885, in the presence of a large number of the shareholders in the Mu