THE HUMAN FRAME. 69 



the purposes of action; the elbow, how powerful must be th&nuscles 

 and tendons, to enable it to lift such heavy weights, and perform with 

 such ease all its various and beautiful functions ; the exquisite distribution 

 of the nerves in the hands and feet, which give us the sense of feeling; 

 the delicate organs of the eye, the ear, the taste, the smell ; all are 

 calculated to feed the contemplative mind, from never-ending sources of 

 wonder and admiration. So true is it, that 



" The proper study of mankind is man." 



In the construction of the haman frame, and essential to life, are 

 numerous bones for strength, hundreds of muscles and tendons for 

 action, nerves spread every where for sensation, hundreds of arteries to 

 carry out the blood, hundreds of veins to bring it back again into the 

 system, and hundreds of glands performing all kinds of secretions, besides 

 an infinite number of tubes to absorb and convey nutriment to the 

 blood. 



The heart is the centre of the system, from which the blood circulates 

 through the frame by thousands of arteries, givingwarmth, life and motion. 

 The blood is driven from the heart of a human being in the form and 

 force of water, forced by a common syringe ; the blood in a man weighs 

 about 301bs., and our being depends upon its action, by the constant 

 circulation from the heart. Until the discoveries of the great Harvey, 

 this action was never perfectly understood. This stock of precious fluid 

 is not allowed by nature to remain at the extremities of the arteries, but 

 is instantly taken up by another set of tubes (the veins) and brought 

 back again to the heart. The arteries into which the blood is forced, 

 branch in every direction through the body, like the roots, branches, 

 and leaves of a tree, running through the substance of the bones, and 

 through every part of the animal system, till they are lost in such fine 

 tubes, as to be wholly invisible. 



In this manner they distribute nourishment, supply perspiration, 

 and renew all waste of the skin ; and by passing through the glands in 

 every part of the body, all the animal secretions are elaborated. Four 

 thousand times in every hour each cavity of the heart is called into 

 action, and all the blood in the body passes through the heart fourteen 

 times in every minute. In the parts where the arteries are lost to sight, 

 the veins take their rise, and in their commencement are also imper- 

 ceptible. The blood is then of a dark colour, and as it returns to the 



