AUTHOR'S PREFACE. 



deration, that whilst works of literature, being fast rooted 

 fa the depths of human feeling, imagination, and reason, 

 suffer little from the lapse of time, it is otherwise with 

 works which treat of subjects dependent on the progress of 

 experimental knowledge. The improvement of instruments, 

 and the continued enlargement of the field of observation, 

 render investigations into natural phenomena and physical 

 laws liable to become antiquated, to lose their interest, and 

 to cease to be read. Such reflections are not entirely desti- 

 tute of foundation; yet none who are deeply penetrated 

 with a true and genuine love of nature, and with a lively 

 appreciation of the true charm and dignity of the study of 

 her laws, can ever view with discouragement or regret that 

 which is connected with the enlargement of the boundaries 

 of our knowledge. Many and important portions of this 

 knowledge, both as regards the phenomena of the celestial 

 spaces and those belonging to our own planet, are already 

 based on foundations too firm to be lightly shaken ; although 

 in other portions, general laws will doubtless take the place 

 of those which are more limited in their application, new 

 forces will be discovered, and substances considered as 

 simple will be decomposed, whilst others will become 

 known. I venture, then, to indulge the hope, that the 

 present attempt to trace in animated characters such a 

 general view of the grandeur of nature, and of the perma- 



