PREFACE. 



ALTHOUGH only three years have passed since the last 

 edition of this work was published, the author has considered 

 it necessary to make many changes, to enlarge it, and to 

 alter its form. This edition contains nearly 100 pages 

 more than the last, and 150 additional illustrations have been 

 introduced. 



The arrangement of the entire work has been simplified. 

 Several of the articles have been re-written, much new matter 

 upon the examination of tissues introduced, and Part V very 

 much extended. . , 



The author has had the advantage of valuable assistance 

 from several friends. To Mr. Sorby he is indebted for articles on 

 the Examination of Rocks and Crystals, and for an able com- 

 munication on Spectrum Microscopic Analysis. Dr. Maddox 

 has carefully revised Part IV on Photography, and has added 

 much new matter. Mr. Highley has assisted the author in 

 preparing the section on Collecting and Dredging, and that 

 on Aquaria and Vivaria. 



L. S. B. 



6 1 , GROSVENOR STREET, W. <7ti d 



November, 1867. 



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