PREFACE TO FIRST EDITION. is 



owing to so much being put in. The reproach on both 

 sides would be just, yet it seemed better to give even a fe\v 

 of the leading discoveries and theories of our own time than 

 to leave the student with such crude ideas of many branches 

 of science as he must have had if the history had ended 

 with the eighteenth century. 



When treating of such varied subjects, many of them pre- 

 senting great difficulties both as regards historical and scien- 

 tific accuracy, I cannot expect to have succeeded equally 

 in all, and must trust to the hope of a future edition to 

 correct such grave errors as will doubtless be pointed out, 

 in spite of the care with which I have endeavoured to verify 

 the statements made. 



As the size of the book makes it impossible to give the 

 numerous references which would occur on every page, I 

 have named at the end of each chapter a few of the works 

 consulted in its preparation, choosing always in preference 

 those which will be useful to the reader if he cares to refer 

 to them. I had also prepared questions on the work ; but 

 those competent to give an opinion, tell me that teachers 

 in these days prefer to prepare their own lessons. I have 

 therefore substituted, at p. 481, a chronological table of the 

 various sciences, by means of which questions can be 

 framed, either upon the discoveries of any given period, or 

 on the progressive advance, through several centuries, of 

 any of the five main divisions of science which are dealt 

 with in this volume. 



In conclusion, I wish to acknowledge my obligations to 

 many kind friends, and especially to Mr. A. R. Wallace 



