There is no really efficacious mode of preparing a woman to take a _rational_ care of the health of a family, except by communicating that knowledge, in regard to the construction of the body, and the laws of health, which is the basis of the medical profession. Not that a woman should undertake the minute and extensive investigation requisite for a physician; but she should gain a general knowledge of first principles, as a guide to her judgement in emergencies when she can rely on no other aid. Therefore, before attempting to give any specific directions on the subject of this chapter, a short sketch of the construction of the human frame will be given, with a notice of some of the general principles, on which specific rules in regard to health are based. This description will be arranged under the general heads of BONES, MUSCLES, NERVES, BLOOD-VESSELS, ORGANS OF DIGESTION AND RESPIRATION, and THE SKIN. BONES. The bones are the most solid parts of the body. They are designed to protect and sustain it, and also to secure voluntary motion. They are about two hundred and fifty in number, (there being sometimes a few more or less,) and are fastened together by cartilage, or gristle, a substance like the bones, but softer, and more elastic. In order to convey a more clear and correct idea of the form, relative position, and connection, of the bones constituting the human framework, the engraving on page 70, (Fig. 1,) is given. [Illustration: Fig. 1.] By the preceding engraving, it will be seen, that the _cranium_, or _skull_, consists of several distinct pieces, which are united by sutures, (or seams,) as represented by the zigzag lines; _a_, being the _frontal bone_; _b_, the _parietal bone_; _c_, the _temporal bone_; and _d_, the place of the _occipital bone_, which forms the back part of the head, and therefore is not seen in the engraving. The _nasal bones_, or bones of the nose, are shown at _e_; _f_, is the _cheek bone_; _g_, the _upper_, and _h_, the _lower, jaw bones_; _i_, _i_, the _spinal column_, or back bone, consisting of numerous small bones, called _vertebrae_; _j_, _j_, the seven _true ribs_, which are fastened to the spine, behind, and by the _cartilages_, _k_, _k_, to the _sternum_, or _breast bone_, _l_, in front; _m_, _m_, are the first three _false ribs_, which are so called, because they are not united directly to the breast bone, but by cartilages to the seventh true rib; _n_, _n_, are the lower two _false_, which are also called _floating, ribs_, because they are not connected with the breast bone, nor the other ribs, in front; _o_, _o_, _p_, _q_, are the bones of the _pelvis_, which is the foundation on which the spine rests; _r_, _r_, are the _collar bones_; _s_, _s_, the _shoulder blades_; _t_, _t_, the bones of the _upper arm_; _u_, _u_, the _elbow joints_, where the bones of the upper arm and fore arm are united in such a way that they can move like a hinge; _v_ _w_, _v_ _w_, are the