PREFACE. 



The Fourth Edition of this treatise met a wider de- 

 mand than anticipated and the Fifth Edition has to be 

 undertaken within a year from the publication date of its 

 predecessor bringing the work to the end of its thir- 

 teenth thousand. The writer rejoices in this large 

 demand as a token of the usefulness of the undertaking. 



The Fifth Edition returns to large octavo form as 

 preferable to a quarto for a book which is intended to be 

 always at hand as a guide in real work. Technical works 

 are largely in octavo form. The picturesque quarto of the 

 Fourth Edition, while admired by connoisseurs in art 

 printing, was condemned by others who found it agreeing 

 neither in length or breadth with other books they com- 

 monly used and therefore inconvenient and undesirable. 



In the preparation of the Fifth Edition the writer has 

 seized the opportunity to bring the contents abreast of a 

 new decade by incorporating the most recent lessons of 

 progressive experience and repeats the request which he 

 has made in earlier editions that all readers whose obser- 

 vation and work teach them any better way than he has 

 described shall share with him the advantage of such 

 greater wisdom. 



EDWARD J. WICKSON. 



University of California, 



Berkeley, March, 1910. 



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