PREFACE TO FIRST EDITION. 



by teaching children a few elementary facts of the various 

 branches of science; but, though such instruction is of 

 immense value, something more is required in order that 

 the mind may be prepared to follow intelligently the great 

 movement of modern thought The leading principles of 

 science ought in some measure to be understood ; and these 

 will, I believe, be most easily and effectually taught by 

 showing the steps by which each science has attained its 

 present importance. 



It is this task which I have endeavoured to accomplish ; 

 and if teachers will make their pupils master the explana- 

 tions given in these pages and, where ve*r it is possible, try 

 the experiments suggested, I venture to hope that this little 

 work may supply that modest amount of scientific informa- 

 tion which every one ought to possess, while, at the same 

 time, it will form a useful groundwork for those who wish 

 afterwards to study any special branch of science. 



The plan adopted has been to speak of discoveries in 

 their historical order, and to endeavour to give such a 

 description of each as can be understood by any person of 

 ordinary intelligence. This has made it necessary to select 

 among subjects of equal importance those which could be 

 dealt with in plain language, and to avoid passing allusions 

 to such as did not admit of such explanation. 



The history of the nineteenth century has been a very 

 difficult and I fear scarcely a successful task; for, while 

 those who know anything of the subjects mentioned will 

 feel that the account is very defective owing to so much 

 being left out, the beginner will probably find it difficult 



