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OBJECT OF THE WORK. 



THE object of this series, though it has been prepared 

 with special reference to the young, and is written to a 

 considerable extent in a narrative form, is not mainly to 

 amuse the readers with the interest of incident and ad- 

 venture, nor even to entertain them with accounts of cu- 

 rious or wonderful phenomena, but to give to those who, 

 though perhaps still young, have attained, in respect to 

 their powers of observation and reflection, to a certain 

 degree of development, some substantial and thorough 

 instruction in respect to the fundamental principles of 

 the sciences treated of in the several volumes. The pleas- 

 ure, therefore, which the readers of these pages will de- 

 rive from the perusal of them, so far as the object which 

 the author has in view is attained, will be that of under- 

 standing principles which will be in some respects new 

 to them, and which it will often require careful attention 

 on their part fully to comprehend, and of perceiving sub- 

 sequently by means of these principles the import and 

 significance of phenomena occurring around them which 

 had before been mysterious or unmeaning. 



In the preparation of the volumes the author has been 

 greatly indebted to the works of recent European, and 

 especially French writers, both for the clear and succinct 

 expositions they have given of the results of modern in- 

 vestigations and discoveries, and also for the designs and 

 engravings with which they have illustrated them. 



