When the body is come to its full height, and is extend I into its just dimensions, it then also begins to receive an adui-tional bulk, which rather loads than assists it. This is formed of fat, which, generally, at about the age of forty, covers all the muscles, and interrupts their activity. Every exertion is then performed with greater labour, and the increase of size only serves as the forerunner of decay.

The bones also become every day more solid. In the, bryo they are almost as soft as the muscles and the flesh, but by degrees they harden, and acquire their proper vigour; but: still, for the purpose of circulation, they are furnished through all their substance with their proper canals. Nevertheless, these canals are of very different capacities during the different stages of life. In infancy they are capacious, and the blood flows almost as freely through the bones as through any other part of the body ; in manhood their size is greatly diminished, the vessels are almost imperceptible, and the circulation is proportionably slow. But in the decline of life, the blood which flows through the bones, no longer contributing to their growth, must necessarily serve to increase their hardness. The channels which run through the human frame may be compared to those pipes that we see crusted on the inside, by the water, for a long continuance, running through them. Both every day grow less and less, by the small rigid particles which are deposited within them. Thus, as the vessels are by degrees diminished, the juices also, which circulate through them, are diminished in proportion ; till at length, in old age, these props of the human frame are not only more solid, but more brittle.

The cartilages, likewise, grow more rigid; the juices circulating throug them, every day contribute to make them harder, so that those parts which in youth are elastic and pliant, in age become hard and bony, consequently the motion of the joints must became more difficult. Thus, in old age, every action of the body is performed with labour, and the cartilages, formerly so supple, will now sooner break than bend.

As the cartilages acquire hardness, and unfit the joints foi motion, so also that mucous liquor, which is always secreted between the joints, and which serves, like oil to a hinge, to give them an easy and ready play, is now grown more scanty It becomes thicker and more clammy, more unfit for answering the purposes of motion, and from thence, in old age every joint is stiff and awkward. At every motion this clammy liquoi is heard to crack ; and it is not without a great effort of the muscles, that its resistance is overcome. Old persons have been known, that seldom moved a single joint without thus giving notice of the violence that was done to it.

The membranes that cover the bones, joints, and the rest of the body, become, as we grow old, more dense and more dry. Those which surround the bones soon cease to be ductile. The fibres, of which the muscles or flesh is composed, become every day more rigid; and while, to the touch, the body seems, as we advance in years, to grow softer, it is in reality increasing in hardness. It is the skin, and not the flesh, that we feel on such occasions. The fat, and the flabbiness of it, seem to give an appearance of softness, which the flesh itself is very far from having. None can doubt this after trying the difference between the flesh of young and old animals. The first is soft and tender, the last is hard and dry.

The skin is the only part of the body that age does not harden ; that stretches to every degree of tension ; and we have often frightful instances of its pliancy, in many disorders which are incident to humanity. In youth, while the body is vigorous and increasing, it continues to give way to its growth. But although it thus adapts itself to our increase, its does not in the same manner conform to our decay. The skin, in youth and health, is plump, glossy, veined, and clear; but when the body begins to decline, it has not elasticity enough to shrink entirely with its diminution; it becomes dark or yellow, and hangs in wrinkles, which no cosmetic can remove. The wrinkles of the body in general proceed from this cause ; but those of the face seem to proceed from another, namely, from that variety of positions into which it is put by the speech, the food, or the passions. Every grimace, every passion, and every gratification of appetite, puts the visage into different forms. These are visible enough in young persons ; but what at first was accidental or transitory, becomes, by habit, unalterably fixed in the visage as it grows older.

Hence, as we advance in age, the bones, the cartilages, the membranes, the flesh, and every fibre of the body, becomes more soiid, more dry, and more brittle. Every part shrinks motion becomes more slow, the circulation of the fluids is performed with less freedom; perspiration diminishes; the secretions alter, the digestion becomes laborious; and the juices no longer serve to convey their accustomed nourish-nent. Thus the body dies by little and little, and all its functions are diminished by degrees; life is driven from one part of the frame to another; universal rigidity prevails; and death, at last, seizes upon the remnant that is left.

As the bones, the cartilages, the muscles, and all other parts of the body, are softer in women than in men, these parts must, of consequence, require a longer time to arrive at that state of hardness which occasions death. Women, therefore, ought to be longer in growing old than men, and this is, generally speaking, the case. If we consult the tables which have been drawn up respecting human life, we shall find that, after a certain age, they are more long-lived than men, all other circumstances the same. Thus a woman of sixty has a greater probability, than a man of the same age, of living till eighty.