PREFACE. 



THE object of this publication is, to 

 afford a useful companion to such Stu- 

 dents as may attend Lectures in the 

 Universities, at the Royal Institution, 

 or elsewhere ; and also to enable the 

 Masters of private Seminaries, with a 

 very moderate Apparatus, occasionally 

 to indulge their pupils with a practical 

 Course of Lectures on one or all of the 

 important branches of Experimental Phi- 

 losophy, Astronomy, and Chemistry. 



Having published some years ago 

 " The Economy of Nature/' the author 

 thinks it necessary to state, that both 

 the plan and arrangement of that work 

 are essentially different from those of the 

 present. The Economy of Nature does 

 not contain Astronomy, nor, in fact, 

 Chemistry, as a distinct science ; on the 

 other hand, a very large portion of that 

 work is occupied with Mineralogy and 

 Physiology, which in this are purposely 

 omitted. Even the subjects which are 

 common to both will be found to be dif- 

 ferently treated in these Lectures. 



February 20, 1808. 



