- 



PREFACE. 



THE object of the present volume is to lay be- 

 fore the public a plain and intelligible description 

 of the structure and uses of some of the more im- 

 portant organs of the human body, and to show how 

 information of this kind may be usefully applied 

 both to the preservation of health and to the im- 

 provement of physical and mental education. In 

 selecting the functions to be treated of, I have pre- 

 ferred to examine those which are at once most 

 influential in their operation on the general sys- 

 tem, and at the same time least familiarly known. 

 Some, accordingly, whose sphere of action is com- 

 paratively subordinate, I have not even named ; and 

 to others of essential consequence in the animal 

 economy, such as that of digestion, I have merely 

 alluded. To include the first would have added 

 to the difficulties of the reader, by the multiplicity 

 of unimportant details ; and to treat of the latter 

 would have been, in a great measure, a work of su- 

 pererogation, as treatises on the digestive organs 

 are already in extensive circulation. 



In offering practical rules for the guidance of the 

 reader, it has been my constant endeavour to ex- 

 hibit the relation subsisting between them and the 



