« AnteriorContinuar »
The deeply interesting event of a matrimonial engagement, however, very speedily draws him off from the indulgence of his grateful feelings, and for the pleasure we have derived from his varied and interesting narrative, the good humour, the occasional pathos, and the graphic power of his descriptions, we know no better wish which we can utter in his favour, than that bis happiness, in this state, may not end but with his life.
ART. X. - The Hand, its Mechanism and Vital Endowments, as
evincing Design, being the Fourth Bridgewater Treatise on the Power, Wisdom, and Goodness of God, as manifested in ' the Creation. By Sir Charles Bell, K.G., F.R.S., L. and E.,
Prof. Roy. Coll. Surg., and Memb. of Council. 1 vol. London:
W. Pickering. 1833. Sir CHARLES commences his treatise by a very remarkable declaration. He says, that the reflections contained in this essay have not been suggested by the Earl of Bridgewater's liberality, and, there fore, the argument which is the whole end of the present volume, will not be unwillingly listened to, because it is not the argument got up for the moment, but it is the produce of a long course of study, directed with entirely distinct views from any that could be referred to the proposed reward emanating
from the generous spirit of the deceased nobleman. The subjects of this essay form the natural accompaniments of those courses of anatomical lectures which, as an anatomical teacher, Sir Charles had to give to young men; and, therefore, the results which he now communicates are not to be considered as a series of conclusions piled up for the moment, and to suit an occasion, but must be regarded as the sole result of long deliberation, quite independent of any temporary provocation or allurement.
There can be no difference of opinion on the point which is insisted upon with great ability by Sir Charles Bell
, that an examination of the whole extent of animated nature, and the full contemplation of it in all its bearings will necessarily lead to the following conclusions: first, that there is design in the mechanical construction of animals; secondly, that benevolence is perceptible in the endowments of the living properties possessed by these animals; and that, lastly, good upon the whole is the grand result.
In order to demonstrate these propositions, the learned author has selected that peculiar, and, as he shows, truly wonderful agent of the reasoning powers of man, the human hand, as the subject of his illustration. This instrument, in his view, is the only one which corresponds in its sensibility, and its motion, with that ingenuity which converts the being, the very weakest in his means of natural defence, into the self-constituted monarch of the whole multitude of individuals which constitute the animated and inanimate world.
Supposing the human hand to be described, as it well might, as an extremity, which has the thumb opposed to the fingers, thus forming part of an instrument for prehension, or the seizing of objects :-- if the description of the human hand ended there, the monkey would be much better off than man, because, instead of one pair of instruments capable of such powers as we have mentioned, and which only exist in man, the monkey has two pair; and thus far the latter would have the advantage of the former. Nay, to go further, certain monkeys are provided with a still simpler apparatus, namely, the tail, which, in some species, can do the business of the hand, still
supposing that the hand in man is nothing more than an agent in pre hension. Many animals can turn their extremities to the greatest account; certainly they can do a great deal for their own convenience, their safety, their pleasure, &c., by means of their four hands, which it is not in the power of man to effect. But then what would be the consequence in case that man was placed on a par with those animals in the extent of the physical resources which their hands afford them? What else but a total destruction of the peculiar adaptations of his single pair of hands to be the secret organ of his peculiar endowment,-an immortal mind. Many a century ago was it that Galen said: “Did man possess the natural armour of the brutes, he would no longer work as an artificer, nor protect himself with a breast-plate, nor fashion a sword or spear, nor invent a bridle to mount the horse and to hunt the lion. Neither could he follow the arts of peace, construct the pipe and lyre, erect houses, place altars, inscribe laws, and through letters and the ingenuity of the hand, hold communion with the wisdom of antiquity, and at one time to converse with Plato, and at another with Aristotle and Hippocrates. But the hand of man does not own its singular privileges to its mechanical composition alone; it derives its chief claims of superiority to its being part of a 'magnificent frame-work with many parts of which the hand holds a close connection."
But, it may be said, that the bones and joints of the hand, so far from being peculiar to man, are found in all other animals with vertebræ. This is undoubtedly, the case, and comparative anatomy proves beyond all question, that the bones which compose the upper limbs of man are to be seen in the fin of the whale, in the paddle of the turtle, and in the wing of the bird; that is to say, these bones exist in the series of animals just specified, but still modified with such extraordinary ingenuity, as to be exactly adapted to the necessities of each animal possessing them; thus do they assume in the lion and the bear the formation of the claw,' in the horse of the hoof, in the camel of the yielding and spreading foot, and in the bear or sloth, of claw which can dig or climb. Thé human hand, then, is distinguished by a combination of all the uses to which the bones composing it are put in other animals, and thus has it the power of performing the most delicate, minute,
and complicated movements. To illustrate these positions, Sir Charles proceeds to describe the various modifications of these bones as they are presented, first, in man, then in the other mammalia, next in birds, and, finally, in reptiles, amphibious animals, and fishes. He commences with a description of the shoulder in man, pointing out in the first place the uniformity with which the lower extremities are more strong and solid than the upper. The whole of the arrangements of the joints and muscles belonging to the lower extremity în man being destined to enable him to maintain the upright position, they constitute a broad distinction between him and all other animals. As it would be only to confuse the reader if we were to attempt to follow the author through his descriptions of the bones of the upper extremity as they are found in man and other animals, particularly as we cannot transfer to our pages the illustrations by which they are made intelligible, we are under the necessity of passing over this portion of the subject.
ct. We ould, however, do injustice to the manner in which the interesting theme is treated by the author, were we to omit his concluding reflections on the proofs of a general conformity between the parts of a skeleton, these being so admirably adjusted, as that the examination of even a fragment of one of the bones will be sufficient to indicate the whole structure, rank, and habits of the animal. This wonderful phenomenon is announced in the following passage:
Suppose a man ignorant of anatomy to pick up a bone in an unexplored country, he learns nothing, except that some animal has lived and died there; but the anatomist can, by that single bone, estimate, not merely the size of the animal, as well as if he saw the print of its foot, but the form and joints of the skeleton, the structure of its jaws and teeth, the nature of its food, and its internal economy. This, to one ignorant of the subject, must appear wonderful, but it is after this manner that the anatomist proceeds. Let us suppose that he has taken up that portion of bone in the limb of the quadruped which corresponds to the human radius; and that he finds that the form of the bone does not admit of free-motion in various directions, like the paw of the carnivorous creature. It is obvious, by the structure of the part, that the limb must have been merely for supporting the animal, and for progression, and not for seizing prey. This leads him to the fact that there were no bones resembling those of the hand and fingers, or those of the claws of the tiger ; for the motions which that conformation of bones permits in the paw, would be useless, without the rotation of the wrist-he concludes that these bones were formed in one mass, like the cannon bone, pastern bone, and coffin bones of the horse's foot.
• The motion limited to flexion and extension of the foot of a hoofed animal implies the absence of a collar bone and a restrained motion in the shoulder joint ; and thus the naturalist, from the specimen in his hand, has got a perfect notion of all the bones of the anterior extremity! The motions of the extremities imply a condition of the spine which unités them. Each bone of the spine will have that form which permits the bounding of the stag, or the galloping of the horse, but it will not have that manner of joining which admits of the turning or writhing of the spine, as in the leopard or the tiger.
* And now he comes to the head : the teeth of a carnivorous animal, he says, would be useless to rend prey, unless there were claws to hold it, and a mobility of the extremities like that of the hand, to grasp it. He considers, therefore, that the front teeth must have been for brousing, and the back teeth for grinding. The socketing of the teeth in the jaws gives a peculiar form to these bones, and the muscles which move them are also peculiar ; in short, he forms a conception of the shape of the skull. From this point he may set out anew, for by the form of the teeth, he ascertains the nature of the stomach, the length of the intestines, and all the peculiarities which mark a vegetable feeder.
* Thus the whole parts of the animal system are so connected with one another, that from one single bone or fragment of bone, be it of the jaw, or of the spine, or of the extremity, a really accurate conception of the shape, motions, and habits of the animal, may be formed.'pp. 80, 81, 82.
The muscular apparatus of the upper extremity next occupies the pen of the author, and some very interesting and curious facts are stated, displaying the principles of the mechanism of motion in our bodies. He shows how the muscles which lie over portions of two bones have their fibres arranged, not longitudinally, but obliquely, and thus in contracting, whilst they lose a great deal of power, they, at the same time acquire a great deal of velocity. Sir Charles illustrates his statement by reference to some common mechanical contrivances. A certain power, he supposes, of wind or of water being obtained, the machinery is moved; but it is desired to give a blow, with a velocity far greater than the motion of the water or the turning of the wheels. For this purpose a fly-wheel is put on, the spokes of which may be considered as long levers. The wheel moves very slowly, at first ; but being once in motion, each impulse accelerates it with more facility; at length, it acquires a rapidity, and a centrifugal force which nothing can equal in its effects, but the explosion of gunpowder. The mechanist not having calculated the power of accelerated motion in a heavy wheel, has seen his machinery split and burst up, and the walls of the house blown out as by the bursting of a bomb-shell. A body at rest receives an impulse from another, which puts it into motion-it receives a second blow ; now this second blow has much greater effect than the first, for the power of the first was exhausted in changing the body from a state of rest to that of motion ; but being in motion when it receives the second blow, the whole power is bestowed on the acceleration of its motion; and so on, by the third and fourth blows, until the body moves with a velocity, equal to that of the body from which the impulse is originally given. The slight blow given to a boy's hoop is sufficient to keep it running; and just so the fly-wheel of a machine is kept in rapid action by a succession of impulses, each of which would hardly put it in motion. If we attempt to
stop the wheel, it will give a blow in which a hundred lesser impulses are combined and multiplied.
Now, in the machinery of the body amongst animals, there is the same interchange between velocity and force, but certainly in a less degree, and it is on this principle that a lady can move her fingers in such a way as to play on a piano, a compositor arrange his types, and, in short, this is the arrangement by which man adapts his hand and fingers to the thousand actions in which he is engaged every
view that we can take of muscular power, it is an object of wonder and admiration; for, supposing the whole of the principles which govern mechanics were transferred to the animal body, let it have all the advantages which can be derived from the laws of gravity, of hydraulics, mechanics, and even steam power, yet how little could they serve to produce that power, simple and plain as it appears to be, the inherent faculty of contracting and relaxing which the muscles possess. If we consider the matter of which muscle is composed, we shall find that, chemically examined, it is nothing but the fibrine of the blood; yet is it endowed with the power just mentioned, and which is so essential to all the great functions of life. The means employed for supplying the muscles with blood, on the quantity of which depends the degree of the contractile power, are next considered by the author, who refers to the commonly received opinion, that the properties of the right hand, as compared with those of the left, are superior, and that the difference is caused by the difference in the manner in which the arteries are distributed in each. The notion generally entertained is, that the trunk of the artery going to the right arm, passes off from the heart, so as to admit the blood directly and more forcibly into the small vessels of the arm.
But Sir Charles altogether rejects such an explanation, as it is founded on the common error of seeking in the mechanism the cause of phenomena, which have a deeper source. that there is a distinction in the whole right side of the body, and that the left side is not only the weaker, in regard to muscular strength, but also in its vital or constitutional properties. The development of the organs of action and motion is greatest upon the right side, as may at any time be ascertained by measurement, or the testimony of the tailor or shoemaker ; certainly, this superiority may be said to result from the more frequent exertion of the right hand; but the peculiarity extends to the constitution also; and disease attacks the left extremities more frequently than the right. In opera dancers, we may see that the most difficult feats are performed with the right foot. But their preparatory exercises better evince the natural weakness of the left limb, since these performers are made to give double practice to this limb, in order to avoid awkwardnees in the public exhibition ; for if these exercises be neglected, an ungraceful preference will be given to the right side. In walking behind a person, it is very seldom that we see an equalized motion of the body; and if we look to the left foot, we shall