PREFACE. 



Nearly nine years ago, I was invited, by the Managers 

 of the London Institution, to take part in a series of courses 

 of Educational Lectures ; which were intended to initiate 

 young people in the elements of Physical Science. 



My course was to be the first of the series ; and I made 

 use of the opportunity, thus afforded me, to put into 

 practical shape the ideas, which I had long entertained 

 and advocated, respecting the proper method of approach- 

 ing the study of Nature. 



It appeared to me to be plainly dictated by common 

 sense, that the teacher, who wishes to lead his pupil to 

 form a clear mental picture of the order which pervades 

 the multiform and endlessly shifting phenomena of nature, 

 should commence with the familiar facts of the scholar's 

 daily experience ; and that, from the firm ground of such 

 experience, he should lead the beginner, step by step, to 

 remoter objects and to the less readily comprehensible 

 relations of things. In short, that the knowledge of the 

 child should, of set purpose, be made to grow, in the same 



