INTRODUCTION. 



A book can stand in only one place on the shelves and 

 can have but one class number. Its title, however, may be 

 repeated in a catalogue in as many classes as it has subjects. 

 When entered in the class of its main subject, the number is 

 printed in ordinary roman type ; when entered also in any 

 other class (where the book does not stand) the number is 

 printed in italics. Thus : 



34012 NATURAL LAW. 



34012 : 341 Law of Nature and Nations. 



341 INTERNATIONAL LAW. 



'34012 : 341 Law of Nature and Nations. 



In addition to the significant class number, each book 

 receives a book mark which serves to distinguish it from all 

 other books belonging to the same class. This book mark 

 almost always consists of the first three letters of the author's 

 surname, or of a word selected, according to certain rules, 

 from the title. As the author's surname or the selected word 

 appears first in the clarendon type at the beginning of each 

 entry of the catalogue, the book mark has not been reprinted 

 at the side. In the case, however, of periodicals and publica- 

 tions of societies, where the same first words {Review, Journal, 

 etc.) recur with frequency, it is necessary to choose, more or 

 less arbitrarily, certain letters, usually initials, to represent the 

 titles. These letters are printed immediately after the class 

 number of each book. Thus : 



'343 Anderson, A. M. Criminal law of Scotland. 



'344 Military Law. Manual of military law. 



3405 L.Q. Law Quarterly Review. 



3406 L. London. Society of Comparative Legislation. 

 Journal. 



The actual book mark of the first of these is And. of the 

 second Mil. 



