IV 



so much diligence has been bestowed upon 

 this little work for nearly ten years, so much 

 useful information has been supplied by scientific 

 friends, and so minute a revision has been made 

 of every answer, that it is no presumption to 

 express a hope that this " Guide to the 

 Scientific Knowledge of Things Familiar" will 

 become generally useful and acceptable, not only 

 to the young, but to those advanced to maturer life. 

 In this work some questions occur more than 

 once, because they serve to illustrate different 

 principles ; and whenever cognate questions occur, 

 the answers have been rendered as similar as 

 possible, in order to assist the memory of the 

 learner. 



