attended with little inconvenience; but it shows what the effect is where it does exist; and what loss of faculty there would be if it were more frequent. Now, when we reflect upon the number of muscles, not fewer than four hundred and fortysix, in the human body, known and named*, how contiguous they lie to each other, in layers, as it were, over one another, crossing one another, sometimes embedded in one another, sometimes perforating one another-an arrangement which leaves to each its liberty, and its full play, must necessarily require meditation and counsel.

IV. The following is oftentimes the case with the muscles. Their action is wanted where their situation would be inconvenient. In which case the body of the muscle is placed in some commodious position at a distance, and made to communicate with the point of action by slender strings or wires. If the muscles which move the fingers had been placed in the palm or back of the hand, they would have swelled that part to an awkward and clumsy thickness. The beauty, the proportions of the part, would have been destroyed. They are therefore disposed in the arm, and even up to the elbow, and act by long tendons strapped down at the wrist, and passing under the liga

* Kell's Anatomy, p. 295, ed. 3.

ments to the fingers, and to the joints of the fingers which they are severally to move. In like manner, the muscles which move the toes and many of the joints of the foot, how gracefully are they disposed in the calf of the leg, instead of forming an unwieldy tumefaction in the foot itself! The observation may be repeated of the muscle which draws the nictitating membrane over the eye. Its office is in the front of the eye; but its body is lodged in the back part of the globe, where it lies safe, and where it encumbers nothing.

V. The great mechanical variety in the figure of the muscles may be thus stated. It appears to be a fixed law that the contraction of a muscle shall be towards its centre. Therefore the subject for mechanism on each occasion is, so to modify the figure and adjust the position of the muscle as to produce the motion required agreeably with this law. This can only be done by giving to different muscles a diversity of configuration suited to their several offices, and to their situation with respect to the work which they have to perform. On which account we find them under a multiplicity of forms and attitudes; sometimes with double, sometimes with treble tendons, sometimes with none: sometimes one tendon to several muscles, at other times one mele to

several tendons. The shape of the organ is susceptible of an incalculable variety, whilst the original property of the muscle, the law and line of its contraction, remains the same, and is simple. Herein the muscular system may be said to bear a perfect resemblance to our works of art. An artist does not alter the native quality of his materials, or their laws of action. He takes these as he finds them. His skill and ingenuity are employed in turning them, such as they are, to his account, by giving to the parts of his machine a form and relation in which these unalterable properties may operate to the production of the effects intended as.

35 In the figure of a muscle, given in page 100, it may be observed that the tendons are on different sides of the muscle.

A

B

If we were to plan their arrangement it would be thus: A is the tendinous origin, and B the tendinous insertion; and the muscular fibres run obliquely between them. This obliquity of the fibres is almost universal in the muscles of the limb, and the effect is very important. It needs no reference to mechanics to under

VI. The ejaculations can never too often be repeated-How many things must go right for us

stand, that if we pull obliquely upon a weight we sacrifice a great deal of power. For what advantage, then, is power resigned in the muscle?

"If you wish to draw

B

B

a thing towards any place with the least force, you must pull directly in the line between the thing and the place; but if you wish to draw it as quickly as possible, and do not regard the loss of force, you must pull it obliquely, by drawing it in two directions at once.

Tie

a string to a stone A, and draw it straight towards you at C with one hand; then make a loop on another string, and running the first through it, draw one string in each hand at B B, not towards you, in the line A C, but sideways, till both strings are stretched in a straight line: you will see how much swifter the stone moves than it did before when pulled straightforward. Now this is

to be an hour at ease! how many more for us to be vigorous and active! Yet vigour and activity are, in a vast plurality of instances, preserved in human bodies, notwithstanding that they depend upon so great a number of instruments of motion, and notwithstanding that the defect or disorder sometimes of a very small instrument, of a single pair, for instance, out of the four hundred and forty-six muscles which are employed, may be attended with grievous inconveniency. There is piety and good sense in the following observation taken out of the Religious Philosopher:" "With much compassion," says this writer, "as well as astonishment at the goodness of our loving Creator, have I considered the sad state of a certain gentleman, who, as to the rest, was in pretty good health, but only wanted the use of these two little

proved by mathematical reasoning to be the necessary consequence of forces applied obliquely; there is a loss of power, but a great increase of velocity. The velocity is the thing required to be gained."

By the liberal employment of muscular power, quickness and variety of motion are obtained, and with the advantages which are so well described in the succeeding part of this chapter

* Preliminary Treatise on the Objects, Advantages, and Pleasures of Science. (Library of Useful Knowledge.)