But there are some further observations respecting the spine which ought not to be omitted. The first is, that those intervening cartilages, which we have seen contribute greatly to the flexibility of the spine, serve also another important office; namely, that of protecting the brain. Were it not for the interposition of this elastic material, every motion of the body would produce a jar to the delicate texture of that important organ, and we should suffer almost as much in alighting on our feet, as we do at present by falling on our head. In rearing a marble column, made of several pieces, it is necessary to interpose thin plates of lead or slate between them to prevent the edges coming close together, in which case they would be liable to chip or split off owing to vibration. The cartilage between the different vertebræ of the spine serves precisely the same office: it prevents the vibration of the lower extremities, especially, from being communicated to the brain. 599 is called a hinge-joint, and bends upwards and downwards, which was the first action to be accounted for. But then how is the rotatory motion accomplished; for the hinge-joint evidently admits of only one motion, up and down. It has been already stated, that the second bone, or the dentata, has a tooth like process: this process is half an inch high, and as thick as the little finger: there are two broad fat surfaces, placed like shoulders on each side of it, which correspond to two other simila surfaces on the under side of the atlas. The atlas then is set down flat upon the two high shoulders of the dentata, when, of course, is threaded by the tooth, which the dec carries, and there it turns, as upon pr with the skull upon it, and performs motions of the head from side to side When we nod, we use the upper joint, made by the head itself and when we turn the head round, ** joint made by the insertion of he the dentata into the socket of the But the protection of the brain is still just the same contrivance *** further provided for by the bending form of mounted telescope; it is req the spine. If we take a piece of steel, and the telescope up and down** endeavour to bring its two extremities to- to point it to a star which land art gether, and let one of them go again, it will than another. It is alr straighten itself with a sudden jerk. Such should be able to take a sw also would be the effect in the spine if it were when we want to remove completely upright, instead of being in the point it to another form of an italic f; for then the weight same line. For the would bear equally; the spine would yield hinge on which is par neither to one side nor the other, and, conse- the rotatory mo quently, there would be a resistance from the on which the h pressure on all sides being balanced. In the it, turn round sage form which it actually bears, it is prepared to The chief yield in the direction of its curves. The contrivance is pressure is of necessity more on one side of ing-Resp the column than on the other; and its elas the results ticity is instantly in operation without the The ease jerk. a right or y he me y a d by that on by Darably That henomee experi. that the act in the utmost pre1st the result; ised from the o any position 1, 3. That, while will pull out the o of a hammer will less the force with d will diminish with e; so that it will be ter stones, as in freeite, whinstone, marble, d, we believe it is only in of stones that the experie with effect. it conceive how a large mass be held suspended, in certain canner before adverted to; but ccount for masses being raised in r from every variety of horizontal ed position; nor conceive how, if e the mode in which the two bodies ept attached, it should happen that, no constant force that can be exerted, hatever direction, will loosen the little ce of iron, the force of percussion will do > at once. Let any one procure a plug of he form described, and attach it in the manner mentioned to a mass of stone, and instead of using machinery, let him pull th rope with the hand in any direction, and h will as soon move a tower from its base ained the little plug from its position so certainly by is it the grasping of the Another most artificial contrivance is moment exhibited in the two uppermost vertebræ of in the human neck. Two purposes are served round by them: first, the head has the power of bending forward and backward, as when we been look downward and upward; and, secondly, of turning itself round to a certain extent, as a when we look over the right or left shoulder These two important offices are served by these two bones, which lie one upon another. the highest of which is called the atlas, bably, because it supports the globe or be and the lower one the dentata, because it process or projection rising upon it a The head rests on the up the atlas, which is perforated will be observed, that the a save surface on each vie d the reception of two carap urfaces placed on the lo 1. When, therefore, the 20 tlas, and the convexities responding concavities ed and we direction in which t tlemen keeps the mass attach on of the periment with the n not the that only, where its presence, if it had existed, would have been useless and inconvenient? Why should the atlas have no spinous process which would have prevented its freely turning on the dentata, and yet the dentata itself be furnished with one which even projects beyond the level of the three spinous processes immediately below it, although turned much downward so as not to interfere with the rotation of the atlas ? Why should there be two concave surfaces in the upper side of the atlas, exactly adapted to receive corresponding convexities fixed on the skull, and yet the under side of the same bone have perfectly smooth surfaces, which admit of its gliding upon the dentata with perfect ease, the articulation being fully provided for by the tooth and socket? The preceding instances are generally considered as exhibiting mechanical arrangement and contrivance; but the joints which belong almost to all bones equally demonstrate, in their form, capacities and position, intelligence and contriving wisdom. They are, in some cases, so many mechanical wonders. The joints, which are of most frequent occurrence in the human skeleton, are those which we have already adverted to, under the names of the hinge-joint, and the ball and socket joint; and one or the other of them prevails, as either is best adapted to the motion required. For instance, a ball and socket joint is not requisite at the knee, since the leg stands in need only of a motion backwards and forwards in the same direction: there the hinge-joint is quite sufficient, and, accordingly, there we find it. But the ball and socket is peculiarly required at the hip, to provide not only for the progressive step, but that the interval between the limbs may be enlarged at plea sure. Suppose the case to be reversed, and the inconvenience occasioned by the change is sufficiently obvious: the thighs would have been kept constantly together, while the legs would have a useless rotatory motion; and yet, independently of a Creator who consulted for this convenience, why might not this arrangement have obtained as well as the one which actually does prevail? Why should the same thigh-bone be channelled at one end, and rounded at the other? The hinge-joint is not formed as a hinge is usually formed, by a bolt passing through both parts, and thus holding them together; but a strong stiff membrane, like parchment, rising from the receiving bones, and inserted a little below the received bones, encloses the joint all round: this membrane ties and holds the bones together, so that the protuberances of one are constrained to play truly into the concavities of the other. In some instances, these membranes are thicker in the sides than either before or behind, the chief danger being that the joint would slip out sideways. The same sort of membrane also accompa nies the ball and socket joint. But there is ¦ in some cases, an additional provision against dislocation. In the thigh-bone a very strong, yet flexible ligament rises out of the head of the ball, and is inserted into the bottom of the socket. Itis so elastic as to admit of all the rotatory metions of which the joint is capable, bat so strong as that nothing but the most unnatural violence can pull them asunder. Before we entirely close our observations on the configuration of bones, we must advert to a most useful and striking provision adapted to their use, namely, the regular supply of an oily, slippery mucilage, which constantly softens and lubricates the parts which reh upon each other, and thus diminishes the force of attrition. For the secretion of this important liniment glands are situated nest each joint, and are continually employed in pouring it into the cavities. There are two reflections which present themselves in considering the properties of joints. The first is respecting the firman of animal articulations, which we may, per- | haps, be enabled to judge of from this single observation, That there are millions of animal joints in complete repair and use, at any given moment of time, for one that is dislocated, and this notwithstanding the exertions to which the limbs of animals are continually subjected in this busy world. The other ob servation respecting them is, how well they wear: a limb shall play in its socket, or swing upon its hinge, a hundred times in an hour, for fifty years together, without any diminution of its power and activity. This admirable durability, with which, perhaps, few or none of the works of art, in equal circumstances, can be compared, is owing to the provision made for preventing wear and tear, in part by the cartilage de fending and padding them, and destroying friction; in part by the healing lubrication of the mucilage; and in part to the astonishing property of animal bodies to repair, by assimilation, every portion of them, let it consist of what it may. Such, then, is the skeleton or general frame-work of the human body; so curious, so complicated, so perfect, so wonderful, exhibiting throughout its whole machinery such evident marks of wisdom, contrivance, and intelligence, that the mind which can attentively consider it without acknowledging a Divine framer, is in a state little to be envied. DEPOSITION OF A GRAND VIZIER. When a Grand Vizier is favourably deposed, that is without banishing or putting him to death, it is signified to him by a messenger from the sultan, who goes to his table, and wipes the ink out of his golden pen; this he understands as the sign of dismissal. : VARIETIES. Valuable Machine for Raising Stones. The following valuable instrument to be now described, was invented by Mr. Richardson of Keswick, who received a reward from the Society of Arts for the invention. It has been employed, in some places, for the purpose of clearing uncultivated ground of such large masses of granite and other stones, compre hended under the popular name of whin stone, as could not be moved but by the aid of gunpowder. It is very little known, and yet, as a useful instrument, it well deserves attention. The machine, or instrument, is simply an iron plug, consisting of a ring, a flat part and a cylinder, as represented in the following figure: The cylindrical part may be seven-eights of an inch in diameter at the point, gradually in creasing to about a sixteenth part of an inch more in diameter at the neck, and being about two inches in length. The instrument thus described is easily managed. Of the stone to be raised, however large it may be, it is enough to see the smallest part appear above the surface of the ground. At this part, let a workman, with a mallet, and the common steel-boring chisel of masons, make a small circular hole, about two inches deep, and as perpendicular as possible. This chisel should be of such a size as to make the hole about a sixteenth part of an inch less in diameter than the cylinder itself, so that a stroke or two of a hammer may be necessary to drive the iron home. When the latter is thus driven an inch, more or less, into the stone, the instrument is attached by means of the ring to a crane, or any other raising power; and strange as it will seem, with no other fastening than this simple plug, the heaviest mass will be torn up through every opposing obstacle. We could well pardon incredulity in any one who was, for the first time, told of such an effect produced by such means. When the fact was mentioned to some distinguished men of science in this country, they remained incredulous, and were only convinced by seeing the engine itself at work; and we have not heard that any of these gentlemen have explained the principle of action of the machine. The general opinion, on first witnessing the experiment, was, that the ironplug when driven into the stone, was not precisely in the direction of the moving power, and that the mass was raised and suspended by the plugs being driven into the stone in a slanting direction. This explanation cannot be admitted; and it is to the elasticity of the stone, and not to the direction of the moving force, that we must attribute the effect produced. The iron is forced down by a stroke, and retained in its position by the elastic power of the stone, in the same manner as a similar pin would be held by a block of wood, into which it was forced by the same means; with this difference, that the elastic power exerted upon the iron by the harder stones, would be incomparably greater than that exerted by the wood. That this is the true explanation of the phenomenon, is confirmed by the facts of the experi ment itself; for, 1. It is found that the moving power may be made to act in the direction of the hole with the utmost precision, without varying in the least the result; 2. That, when the mass is raised from the earth, it may be moved into any position without being detached; and, 3. That, while hardly any constant force will pull out the plug, a smart stroke or two of a hammer will do so with ease. Doubtless the force with which the iron is retained will diminish with the elasticity of the stone; 'so that it will be vastly less in the softer stones, as in freestone, than in granite, whinstone, marble, and the like. Indeed, we believe it is only in the latter species of stones that the experiment can be made with effect. A person might conceive how a large mass of stone might be held suspended, in certain cases, in the manner before adverted to; but we cannot account for masses being raised in this manner from every variety of horizontal and inclined position; nor conceive how, if this were the mode in which the two bodies were kept attached, it should happen that, while no constant force that can be exerted, in whatever direction, will loosen the little piece of iron, the force of percussion will do so at once. Let any one procure a plug of the form described, and attach it in the manner mentioned to a mass of stone, and, instead of using machinery, let him pull the rope with the hand in any direction, and he will as soon move a tower from its base as the little plug from its position; so certainly is it the grasping of the stone, and not the direction in which the rope is pulled, that keeps the mass attached. In making the experiment with the machine, it is even neces only, where its presence, if it had existed, would have been useless and inconvenient? Why should the atlas have no spinous process which would have prevented its freely turning on the dentata, and yet the dentata Itself be furnished with one which even projoots beyond the level of the three spinous processes immediately below it, although turned much downward so as not to interfere with the rotation of the atlas ? Why should there be two concave surfaces In the upper side of the atlas, exactly adapted to receive corresponding convexities fixed on the skull, and yet the under side of the same do have perfectly smooth surfaces, which admit of its gliding upon the dentata with perfect ease, the articulation being fully prowall for by the tooth and socket? nies the ball and socket joint. Put the in some cases, an additional provision ap dislocation. In the thigh-bone a very strong, vein ligament rises out of the head of the va is inserted into the bottom of the ESL I so elastic as to admit of all the meters tions of which the joint is capable strong as that nothing but the mas violence can pull them asunder. Before we entirely close our absu on the configuration of bones, we ma to a most useful and striking To to their use, namely, the regular s oily, slippery mucilage, co softens and lubricates the pars upon each other, and thus da force of attrition. For the secret important liniment glands sve s each joint, and are easily pouring it into the cavities The preceding instances are generally con- There are two refecams w Ayured at the ધોર the Valuable Machine for Raising Stones. The following valuable instrument to be now E described, was invented by Mr. Richardson of Keswick, who received a reward from the Society of Arts for the invention. It has been employed, in some places, for the purpose of and clearing uncultivated ground of such large masses of granite and other stones, compres hended under the popular name of whinstone, as could not be moved but by the aid of gunpowder. It is very little known, and yet, as a useful instrument, it well deserves attention. The machine, or instrument, is simply an iron plug, consisting of a ring, a flat part and a cylinder, as represented in the following figure: The cylindrical part may be seven-eights of The instrument thus described is easily machine. The general opinion, on first witnessing the experiment, was, that the ironplug when driven into the stone, was not precisely in the direction of the moving power, and that the mass was raised and suspended by the plugs being driven into the stone in a slanting direction. This explanation cannot be admitted; and it is to the elasticity of the stone, and not to the direction of the moving force, that we must attribute the effect produced. The iron is forced down by a stroke, and retained in its position by the elastic power of the stone, in the same manner as a similar pin would be held by a block of wood, into which it was forced by the same means; with this difference, that the elastic power exerted upon the iron by the harder stones, would be incomparably greater than that exerted by the wood. That this is the true explanation of the phenomenon, is confirmed by the facts of the experi ment itself; for, 1. It is found that the moving power may be made to act in the direction of the hole with the utmost precision, without varying in the least the result; 2. That, when the mass is raised from the earth, it may be moved into any position without being detached; and, 3. That, while hardly any constant force will pull out the plug, a smart stroke or two of a hammer will do so with ease. Doubtless the force with which the iron is retained will diminish with the elasticity of the stone; 'so that it will be vastly less in the softer stones, as in freestone, than in granite, whinstone, marble, and the like. Indeed, we believe it is only in the latter species of stones that the experiment can be made with effect. A person might conceive how a large mass of stone might be held suspended, in certain cases, in the manner before adverted to; but we cannot account for masses being raised in this manner from every variety of horizontal and inclined position; nor conceive how, if this were the mode in which the two bodies were kept attached, it should happen that, while no constant force that can be exerted, in whatever direction, will loosen the little piece of iron, the force of percussion will do so at once. Let any one procure a plug of the form described, and attach it in the Julity in any manner mentioned to a mass of stone, and, ld of such instead of using machinery, let him pull the When rope with the hand in any direction, and he uished will as soon move a tower from its base as ained the little plug from its position; so certainly is it the grasping of the stone, and not the which the rope is pulled, that hed. In making the exit is even neces |