on a pivot. The first upper vertebra is called ATLAS, from its supporting the globe of the head, and is united to it by a hinge or joint, upon which the head plays freely forward or backward, to the right or left, as far back as is necessary.

The bones which compose the vertebræ are twenty-four in number. These having a hole in the middle of each, about the size of a little finger, are placed over each other, forming a canal or channel for the spinal marrow. Between these bones is a tough substance or gristle, very yielding or elastic, almost like India rubber. This keeps the bones from wearing out too fast when they move, and yet allows of their moving pretty freely. "The spine is, really, one of the most curious things in nature. Rope dancers and tumblers will bend their heads back till they almost touch their feet, and bring this straight pile of bones nearly into the shape of a bow. This gristle or cartilage between the vertebræ is so elastic or springy, and also so readily compressed, that people who stand or walk much, are really a little shorter at night than they are in the morning. Rest gives the elastic cartilages time and opportunity to spring back again into their places while we sleep, so that by the next morning we are as tall as ever. It is a fact that old people settle down a little, and are not so tall as in middle age; which is partly owing to these cartilages yielding and yielding till they become at length somewhat thinner."*

You may observe the structure of the vertebræ in a loin of veal; and the back of a hare or rabbit affords a good view of the mode and firmness of the union between them.

Some conception of the strength of the vertebræ may be formed, when we consider the enormous loads which some strong men are able to carry on their backs.

IV. We have now to treat of

THE BONES

of the human frame in general. These consist of a white, hard, brittle substance, supporting and forming the stature of the body, constituting its frame-work, defending its fleshy parts, and giving power to the various muscles.

The number of distinct bones in the human body is about two hundred and fifty, presenting every variety of size and figure, from the bone of the leg, or thigh-bone, which is the

* "House I Live in," p. 41; from which valuable little work the author has derived many useful hints.

largest, to the minute bones of the ear, which are the smallest. The bones are, generally speaking, of three kinds-long bones, broad or flat bones, and round bones. The long bones are hollow, having a channel throughout their entire length, which contains marrow. The broad or flat bones, which are rather of a spongy character, are chiefly those of the head and hipbone; and the round bones are those of the joints. "There is, undoubtedly, LIFE, (though we hardly know what life is,) in bones. While we continue in good health, and the functions of the body are duly performed, there is not much feeling in them; though in some cases of disease they are endued with exquisite sensibility. When the surgeon amputates a limb, the proceeding of sawing through the bone is the least painful part of the operation; though people in general imagine that it is highly so.' When a bone is broken, it is not the bone that

feels so much as the nerves that surround it.

The entire bones of the human body, when perfectly dry, weigh from twelve to twenty pounds. These are the last remains of the human frame. In ancient times, survivors of relatives and friends were very careful about the bones of the departed; keeping them entire, or reducing them by fire to ashes, and then preserving them in urns or vases. An inspired writer in the sacred volume tells us that Joseph "gave commandment concerning his bones;" and Moses, when he and the children of Israel left Egypt, "took the bones of Joseph with him." The structure and functions of the human body display, in a striking manner, the skill and goodness of Him "in whom we live, and move, and have our being." "All my bones shall say, Lord, who is like unto thee?" Psalm xxxv. 10.

The study of the bones is called OSTEOLOGY, from OσTéov, a bone, and λoyos, a discourse.

We now proceed to notice some of those bones which have not yet come under review; such as

1. The RIBS (fig. r r). There are twelve of these curved bones on each side of the body, making twenty-four. They proceed from the vertebræ, and come round to the front of the body; seven of the upper ribs on each side, are united to the STERNUM, or breast-bone (fig. x), and are called TRUE RIBS: the other five, which are not so joined, but are united to the upper ones, or hang loosely at one end, are called FALSE ribs. "In the old by-gone days of ignorance and superstition, a notion

*"House I Live in," p. 33.

prevailed, which is not yet wholly extinct, that the MAN has one rib less on one side than on the other. It was said that as Eve was formed of a rib taken from Adam's side, he and all his male posterity, have one rib the less for it. We hardly need say that this notion is wholly unfounded." Facts are against it, as man has the same number of ribs as woman. Whether in the case of Adam, the Creator substituted another rib for the one taken away, we need not inquire. It is probable that a portion of flesh as well as bone was taken from the side of Adam; for when the woman was brought to him, he said, "This is now bone of my bones, and flesh of my flesh." Gen. ii. 23.

In the position and form of the rib-bones we see what a wise and kind provision has been made by God for the defence of the heart and lungs-the seat of life. These are the walls of the citadel-the guards of vitality. We read in sacred history of one or two men who were assassinated. The assassins knew where to plunge the dagger; for we are expressly told that they smote the victim "under the FIFTH rib;" that is, under the protecting ribs. It was at this particular part, on the left side, that the soldier thrust his spear, when he pierced the heart of the Redeemer on the cross. But while the ribs thus protect the vitals of the human frame, the arms and hands are a sort of outer-guards, defending the ribs and other parts of the body.

2. The COLLAR-BONES (fig. y y), termed the CLAVICLE, are, in form, like the ribs, and extend outwards from the top of the upper arm bone to the neck, or the top of the breast-bone.

3. The SHOULDER-BLADE is the broad flat bone lying at the upper part of the back, and which is so troublesome to many young ladies by its unseemly projection. In the upper part of it is the hollow or socket, in which the round head or ball of the large arm-bone lies and moves. Its form is not much unlike that of a shoulder of mutton. It is called the SCAPULA.

4. There are two bones called the PELVIS, or HIP-BONE (fig. 8 s.) The word pelvis signifies a basin or bowl; and the bone is so called because it helps to contain and support the lower parts of the body. In the centre of the pelvis is a bone denominated the SACRUM, upon which the spine or back-bone rests. (fig. w.)

5. The ARM-BONES consist of one upper,-named the HUMERUS (fig. b b), and two lower, called the RADIUS (fig. d d), and the ULNA (fig. e e), or cubit, as the cubit is the length of a

man's arm from the elbow to the extremity of the little finger. The connection of the bone at the shoulder is such that the arm can be moved in almost every conceivable direction. The two lower bones are joined to the upper at the elbow (fig. c c.) This elbow-joint admits of only one sort of motion, viz., forward and backward, like a door on its hinges. Then the WRIST,— (fig. ff) consisting, as it does, of eight bones, all moveable, and being so connected with the lower bones of the arm as to admit of very free motion,-renders the arm one of the most useful contrivances in the world. It will perform movements as various and as rapid as the trunk of the elephant; and would probably, if it were not so common, excite as much surprise.

6. From the bones of the pelvis or hip-bone proceed the LEG bones. The bone of the THIGH (fig. i i), called the FEMUR, is the largest and strongest bone of the whole human frame. At its upper end, where it is connected with the hip-bone, (fig. hh,) is a round knob or head. This head fits into a corresponding hollow, or cavity of that bone, and is fastened there by strong flexible ligaments or gristly straps. The leg below the knee consists of two bones, the larger called the TIBIA, (fig. m m,) so named because it resembles a tube, or pipe, or hautboy; and the smaller, termed the FIBULA (fig. n n); the latter descending from the upper side of the former to the ankle. At the knee there is a small detached round flat bone, called the KNEE-PAN, or the PATELLA, (fig. kk, ll,) kept in its place by what are denominated TENDONS; this protects the front of the knee-joint. It will be perceived that the leg bones are very similar to those of the arms.

7. The bones of the HAND and Fooт, (fig. 9 g, p p,) are very remarkable. The whole hand with the wrist contains twenty-seven bones. The four longest bones support the palm of the hand, and are joined at one end to the wrist bones, and at the other to the first joint of the fingers. Each of the four fingers has three bones; the thumb only two.

The bones of the foot have a general resemblance to those of the hands. The foot is composed of twenty-six little bones, strongly fastened together by gristles and ligaments. These ligaments yield, when we bear upon the foot, just enough to enable it to conform to the surfaces on which we tread. The instep is the forepart of the upper side of the foot nearest its junction with the leg. The ankle, (fig. o o,) is the joint which connects the foot with the leg. The bones of the feet assist us in

preserving our balance, and in standing upright, and also enable us to perform several progressive motions with greater ease. Before we dismiss the subject of bones, we must say a few words on

8. The TEETH. These are instruments for laying hold of, and masticating or chewing solid food, breaking it into small pieces, and mixing it with saliva or spittle; thus preparing it for more easy digestion in the stomach. They are situated in the jaws, and have a very complicated structure. When the number of teeth is complete, in an adult person, and none have been lost, or extracted, each jaw contains sixteen; and both together, of course, thirty-two. There are four kinds of teeth in each jaw, viz., four front teeth, two canine or dog's teeth, called also eye-teeth, four small grinders, or double teeth, and six large grinders. Of these, half are, of course, on each side. To prevent the teeth from wearing out, as a piece of common bone would do, the crown or body of the tooth, which is that part we see above the gum, is coated all over with something much harder than any bone in the human body. It is called ENAMEL. "Hard as it is, however, enamel will wear out in time. It will wear out much sooner if the teeth be picked with pins and needles. These things are too hard, even for the hard enamel, and are apt to crumble it off. So is the practice of cracking nuts with the teeth; or, indeed, the biting of any substance harder than the crust of good dry bread. If accustomed to bite nothing harder than that is, and if not injured in any other way,-for there are many ways of injuring the teeth, (such as by very hot water, acids, sweets, &c.),—they may, perhaps, last all our lives, as in the case of other animals, and the uncivilized race of man. But if the enamel once gets broken, or removed, so that the air is admitted to the softer bone under it, and affects the nerve, the seat of tooth-ache, which passes through it, the tooth soon becomes hollow or decays. Like any other part of this wonderful frame which God has given us, the teeth will, however, last the longer for being moderately used."* Those kinds of food and drink which injure the stomach, also injure the teeth, and cause the enamel to become soft and break away. One thing more, however, as a practical hint, the teeth must be kept clean. Let the tooth-brush be in constant use. This is a practice, no less

*"House I Live in," p. 64.