With what satisfaction is the mind continually engaged to give pleasure to the body! and with what alacrity are for ever the Members ready to obey the will! Happy harmony, by which we so wonderfully exist! The _solids_ are the canals and springs of life, and the _fluids_, which circulate in those canals, nourish them, and set the springs in action. By the _solids_ we understand, 1st The _bones_; the frame and support of our wonderful structure. 2dly. _Gristles_ or _cartilages_; which cover the ends of the bones, in order to make them move with ease and agility. 3dly. _Muscles_; the fleshy parts, which by a nervous sensation, are induced, either voluntarily or involuntarily, to contract or dilate themselves, in order to give motion to the various parts of our body, to which they are fastened or destined to move. 4thly. _Tendons_; the chords as it were, by which the muscles are fastened to the bones, so as to make them follow the contraction of the muscles. 5thly. _Ligaments_; the chords by which the bones are connected with each other, and which give a firmness to their contact and articulation. 6thly. _Arteries_; the canals which transport the blood from the heart, to all the parts of the body. 7thly. _Veins_; the canals which carry the blood from the remotest arteries (in the most minute parts of the body) back again to the heart, for a new rotation of the blood. 8thly. _Lymphatic Vessels_; which are small cellular canals, that convey the lymph in different parts of the body. 9thly. _Glands_; which are kernels formed to _secrete_ or separate various humours from the blood. 10thly. _Nerves_; these are medullary branches springing from the brain, and distributed in the most minute parts of the body; ordained to give the act of sensation, as the soul of animal activity. 11thly. _Hair_ and _nails_; these are a horny substance, and appropriated either for defence or warmth of the different parts where they are placed. The _fluids_; are, 1st. _Blood_; which is circulated in the arteries and veins, and is the nutriment and source of life. 2dly. The different humours separated by the glands from the blood; of which there are many, as the _lymph_, _serum_, _spittle_, _seed_, _chyle_, _urine_, _gall_, &c. appropriated to different uses, as hereafter will be described. 3dly. _Fat_, and _marrow_ in the bones; which are designed not only as a store of nourishment, but to lubricate and warm the parts where they are lodged. These are the principal materials which compose our wonderful machine. There are various other parts mentioned by Anatomists, both solids and fluids; but as this is designed only to give a universal idea of the most material parts of the structure of this stupendous fabric, we will let this definition suffice, and now consider with what order the principal organs of life act, either in consort, or in opposition to each other. -------------------------------------------