IV PREFACE. 



teacLer Xvill also observe that the principles and import- 

 ant propositions are presented in large and prominent 

 type, and the observations and illustrations in smaller 

 letters. The advantage of this to the learner is most 

 evident. 



Heat, which is often considered as belonging more 

 especially to chemistry, has been discussed at length, and 

 the familiar application of its principles in the industrial 

 arts, in warming and ventilation, in the production of 

 dew, etc., carefully explained. A full and complete 

 outline of the subject of Meteorology has also been 

 given. On the other hand, Astronomy, which is often 

 included in text-books on Natural Philosophy, has been 

 omitted, as rightfully and properly forming the subject 

 of a separate treatise. 



An elementary work on physical science can have little 

 claim to originality, except in the arrangement and classi- 

 fication of subjects, and the selection of illustrations. In 

 this respect the author makes no pretensions, and ac- 

 knowledges his indebtedness to the very superior French 

 treatises of Ganot, Delaunay, Archambault, and to the 

 writings of Miiller, Arnott, Lardner, Brewster, and others. 



The engravings in the present volume are of a superior 

 character, and have been prepared, in part, from new and 

 original designs. 



New Tobk, August, 185Y. 



