position of objects, relative to their centre of gravity." This perception some persons possess more acutely than others, so as to be able, with the eye alone, to test the perpendicular in spires, towers, and other buildings, with the accuracy of a plumb-line. This is quite true, and shews that the equilibrium of external objects is observed by the sense of sight, in addition to the primitive perception in our personal sense of resistance. That the faculty enables us to see objects in their relation to gravitation and mechanical resistance, is farther proved by the effects of its derangement in intoxication and vertigo, when horizontals appear perpendiculars, and vice versa, as occurred to Miss S. L. and Mr John Hunter. Every one has seen a drunk man holding fast by the carpet, in the belief that he should fall from an inclined or perpendicular wall; while the occurrence is not uncommon of the drunkard's conviction that the pavement upon which he falls has risen up and struck him on the forehead. This illusion is instructive: we learn from it that a faculty is required for forming just notions of position in relation to gravitation; and we farther learn that that faculty must not be deranged, else it will mislead us. In a sound state, it feels that the securest position for our bodies-when not lying horizontal, which last position, itself, is only a multiplication of vertical lines on an extended base, -is the perpendicular; as that is the direction of the most powerful attraction. It sees that this is also true of a tower or a wall. Whatever may be the relation of that perpendicular to the heavens, it is vertical to the perception of the faculty in question; and when our own body is the attracted object, the line of the strongest attraction must constitute, to us, what is called up and down. Although our position changes its relation to the heavens at the rate of 1000 miles an hour at the equator, and 560 at Edinburgh, it remains perpendicular, or in the line of the earth's centre, and therefore, to our feelings, never can change. There is no up and down absolutely in space. It is a sensation produced by gravitation on a sense provided for it; and, when that sense is deranged, the perceptions of up and down are no longer to be trusted. It matters not where our heads point; if our feet, or, more properly, the centre of gravity of our bodies, be subject, as it must be, to gravitation in the line of the earth's centre, we will have the feeling of the spot of earth we tread on being permanently below us, and the opposite point of the heavens for the moment, vertically above us. İt puzzled the learned, in the days of Galileo, to conceive how our opposites the antipodes, and we in our turn, stuck on the inverted earth's surface. The witty Buchanan, tutor of James I., wrote a long satirical poem, in Latin hexameters, on the incredible theory; and, with precisely the same degree of light, a young woman

VOL. IX.-NO. XLIII.

lately changed her mind about going as a colonist to Van Diemen's Land, because she saw plainly that there she would live with her head down and her feet up, like a fly on the ceiling; the world, as was shewn to her, being as round as an apple, and while we possess the great advantage of having our heads up, those opposite to us having, of necessity, theirs the other way; a change which no prudent person, especially in female attire, would think of making.

All the engineer's notions of the strength and strain of the materials with which he works, and their adaptation to the desired resistances and counter-resistances, originate in this faculty; the carpenter uses it in every direction of his trade; so does the shipbuilder; for all the improvements by Sir Robert Seppings in that important art, are skilful adaptations and applications of his materials to produce resistance and counter-resistance, strain and counter-strain.

Finally, The distinction between the external sense and the internal faculty at once removes the objection that the convolution between Size and Colouring cannot be the organ of the faculty, because the nerve of muscular feeling is not traced into it; for neither is the optic nerve traced into the organ of Colouring, nor the auditory nerve into the organ of Tune; which organs, respectively, these nerves nevertheless subserve. My position is, that the faculty for applying Force, and for maintaining equilibrium, is as different from the sense of Resistance, as the faculties of Colouring and Tune are from the senses of Sight and Hearing, however close their dependence on these senses; and, if we can and do observe the degree of endowment of Colouring and Tune, by the development of two distinct organs, into neither of which the optic or auditory nerve is traced, so we may observe the degree of endowment of mechanical Force by its own organ, although the nerve of Resistance is not traced into it.

I shall conclude this letter with some remarks on the most appropriate names for the sense and the faculty, respectively; for I have, as yet, rather described than named them, thinking it advisable that their nature should be clearly unfolded before they were definitively named. Dr Spurzheim, denominated his power the faculty of Weight or Resistance, and considered it as cognising momentum, consistency, density, ductility, softness, and hardness. Nothing was changed in the notion of resistance by any of these terms; for, including weight itself, they are all varieties of resistance. Dr Brown likewise adopted Resistance as the sensation of his sagaciously conjectured sense, and concluded that the muscular frame,-which, he said truly, "is not merely a part of the living machinery of motion, but also an organ of sense," is the external organ of that sense. Under the generic term resistance Dr Brown includes hard

ness, softness, roughness, smoothness, liquidity, viscidity, solidity, &c. Sir George Mackenzie's speculations on the name are most instructive: his very uncertainties doubts and variations maintain a progress towards truth; and when, in one of his papers, he modestly gives up the research as beyond his powers, he alludes, in quitting it, to the possibility of the very hypothesis which, with powers far inferior to his, I have above offered reasons for concluding to be the true one. This process Sir George Mackenzie's mind is curious, and extremely interesting.1st, In his Illustrations of Phrenology, p. 160, he sug gests the name, Resistance, as designating the only impression which is left with us by the qualities of weight, hardness, &c. In the same work he conjectures that there may be a faculty which gives us perceptions of Force or power. 2d, In an ingenious paper contributed to the Phrenological Journal, on the faculties exercised in playing at billiards, chess, and other games of skill, Sir George Mackenzie's conjecture of a faculty for Force has gathered strength, and he is much disposed to abandon altogether his first love Resistance, which he erroneously imputes to the sense of Touch. "I am at present," he says, "inclined to think that the organ called that of Weight may be the organ of a fuculty which gives us the notion of force, or mechanical power; that which is required to overcome resistance. Resistance appears to be discovered but by the sense of touch, from which we derive all our notions of hardness, softness, roughness, and smoothness, and which are all of them modes of resistance t. But there is something required to overcome resistance or balance, of which our ideas are perfectly distinct, and which is capable of being compared in degree. This, I apprehend, is not momentum, or vis inertiæ, because this is a quality or property not elicited or known until a body is set in motion. What I look for is that which produces or prevents motion. It is not resistance itself which overcomes resistance, because a body at rest is capable of resisting without exertion being made. Force is the only word that occurs to me at present, for expressing the function of the faculty I suppose to exist, and I must distinguish the special

• Vol. iii. p. 211.

This error mainly prevented Sir George Mackenzie from clearly seeing all the truth. I may here take occasion to remark, that the same error has probably retarded for many years the realization of the benevolent project of a tangible alphabet for the Blind. Characters raised above the level of the paper, are held to be addressed to their sense of Touch. In truth they are addressed to their sense of Resistance, and affect the muscles of their fingers, while no appeal is made to their proper surface sensations of Touch. This last would be done by a judicious disposal of points and edges, to picque, though not to pain or wound, the fingers; and thus two means, instead of one, of distinguishing characters, would be enjoyed by them. As one application of the doctrine of this letter, I hope at a future time to offer you some views on this curious and interesting subject.

nature of the force I have in view, to be, 1st, that derived from muscular exertion, that which we can produce by will. The discovery that, to a certain extent, we have the power to overcome mechanical resistance, may be called instinctive; but still the consciousness of this power must be derived from the intervention of a power of the cerebrum. The notion of muscular power is abstract, i. e. we know it, though we are not exerting it. 2d, I refer the knowledge of force produced from other sources, such as the force produced by expansion, as in the examples of steam, the inflammation of gunpowder, and the force of gravitation and attraction, to the same faculty. We see no causes producing such forces; we are quite ignorant of the nature of that which produces will, and of the manner in which will produces muscular exertion. We know not how the expansive force is brought into action; we only know the fact, that its production follows certain conditions into which matter may be brought. We know nothing of the causes of attractive forces, or what it is that causes weight or gravitation. On the whole, I am induced to consider that there is a faculty which takes cognizance of force generally, and I think that this may be what Mr Simpson was in search of when he made his ingenious speculations on the organ of Weight, and that this organ may be that of the faculty of Force." "The notion of resistance appears to be necessary to us. We know, from experience, that a billiard-ball has something in it that resists, and we cannot make it move merely by willing it to change its position; we apply force to remove it. RESISTANCE AND

FORCE APPEAR, THEREFORE, TO BE DIFFERENT THINGS, EACH REQUIRING A SEPARATE FACULTY BY WHICH WE ARE ENABLED

TO ESTIMATE THEM. Motion is a fact learned through the medium of our senses; and experience tells us that motion is the effect of force applied. We farther learn that force is communicated by motion; and perhaps we may say, that motion is force in action, after having overcome résistance. I now begin to be sensible that my powers will not enable me to carry on this analysis farther, and I must leave my ideas of resistance and force being cognisable BY TWO DISTINCT FACULTIES, to the consideration of our highly gifted phrenologists."* It will be observed that Sir George Mackenzie has again taken Resistance into favour, and formed the happy conjecture of the possibility of there being two faculties concerned in the phenomena of motion and equilibrium; in short, of the very truth which I am now offering to your consideration as demonstrable. 3d, In a subsequent communication+, Resistance is once more at a discount, though

The words in the above page distinguished by capitals were not so marked by Sir G. M.; for he was not sufficiently assured of the truth, at which he had nevertheless arrived, to be so emphatic.

+ Phren. Journ. vol. iv. p. 284.

still admitted as playing a subordinate part. "On farther reflection," he says, "I am satisfied that resistance is too narrow an expression yet for the perception in question, although resistance must be included in any more extensive term, just as weight is included in resistance. In a former communication, I stated some reasons for thinking that the more general perception in question is force; I now offer you some farther considerations in support of that conclusion." Referring to the paper itself for the statement at length, I will endeavour to give the substance of Sir G. M.'s argument. Every knowing faculty, he thinks, cognises something constant and invariable in nature, as space, time, order, number, light, sound. Resistance, weight, equilibrium, are not constant, but force is *. Motion is the effect of force overcoming resistance; it is the sensible exhibition of the effect of force. But we find all nature in motion; no body is at rest except relatively to other bodies. Force is in constant operation; different forces always acting keep the planets in their orbits. Force may be estimated by Causality, but Causality would never of itself cognise force, more than it would light or sound. Equilibrium is the harmony of forces, just as concord is the harmony of sounds. In equilibrium, forces are combined with resistance in such a manner as to be equally divided around it. Being thus an effect," says Sir G. Mackenzie, " arising out of combined causes, and discovered to us after we acquire a knowledge of force and resistance, the perception of equilibrium appears to me a subordinate function. I give up my notion that resistance is cognisable by a distinct faculty. It is not peculiar to the sense of touch, for we know resistance by seeing its effects as well as by feeling them. I now consider it as subordinate, and including various qualities of matter, as will be seen in the following arrangement:

66

The above process of metaphysical thinking is most in

With due deference to Sir George Mackenzie, I am inclined to think that his doctrine of constant force without constant resistance, is an error, if not a