404 THE PRINCIPLES OP SCIENCE. 



different heads, the frontier of the dubious region would 

 itself be a mere matter of doubt. I never turn from a 

 classed catalogue to an alphabetical one without a feeling 

 of relief and security. With the latter I can always, by 

 taking proper pains, make a library yield its utmost ; 

 with the former I can never be satisfied that I have 

 taken proper pains, until I have made it, in fact, as many 

 different catalogues as there are different headings, with 

 separate trouble for each. Those to whom bibliographical 

 research is familiar, know that they have much more 

 frequently to hunt an author than a subject : they know 

 also that in searching for a subject, it is never safe to 

 take another person's view, however good, of the limits 

 of that subject with reference to their own particular 

 purposes.' 



It is often very desirable, however, that an alphabetical 

 name catalogue should be accompanied by a subordinate 

 Bubject catalogue, but in this case no attempt should 

 be made to devise a theoretically complete classification. 

 Every principal subject treated in a book should be entered 

 separately in an alphabetical list, under the name most 

 likely to occur to the searcher, or under several names. 

 This method was partially carried out in Watts's valuable 

 * Bibliotheca Britannica,' but it was perfectly applied in the 

 admirable subject index to the ' British Catalogue of Books/ 

 and equally well in the ' Catalogue of the Manchester Free 

 Library at Campfield/ this latter being the most perfect 

 model of a printed catalogue with which I am acquainted. 

 The public Catalogue of the British Museum is arranged 

 as far as possible according to the alphabetical order of 

 the author's names, but in writing the titles for this 

 catalogue several copies are simultaneously produced by a 

 manifold writer, so that a catalogue according to the order 

 of the books on the shelves, and another according to the 

 first words of the title-page, are created by a mere re- 



