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PREFACE: 



THE following collection of Tables in the more elementary 

 portions of Natural Science is intended to supplement the 

 ordinary text-books, and to assist learners, teachers, and those 

 engaged in Laboratory work. By the use of such a book those 

 learners who depend solely upon oral instruction may be saved 

 the trouble of copying down long lists of figures, and others 

 may frequently find data additional or external to those given 

 in their text-books. To teachers, who have to turn rapidly from 

 one branch of science to another, the tables will, I hope, be 

 convenient in the construction of numerical problems, which 

 so powerfully assist in fixing and rendering clear the ideas 

 gained from lectures or text-books, and will serve to remind 

 them of a forgotten number without an irritating search 

 through bulky manuals. Persons engaged in practical work 

 will find the book useful both as a compendium of numerical 

 facts outside their particular branch of study, and as an aid 

 in working out the results of their own experiments. 



In preparing a work, however elementary, of so wide a scope 

 as this, an author must depend much on the kind assistance 

 of those specially cognisant of the various branches of which 



