Indexing. The need of indexing has become more urgent as the mass of materials to be indexed has increased, and the circle of those who wish to use these materials has become wider. Lord Campbell proposed to bring a bill into parliament to deprive an author who published a book without an index of the privilege of copyright. There are two classes of books to be indexed—viz. books of facts and books of opinion. In the indexing of the first class, experience, care, and common sense are needed, and the work must be systematic and not casual. In the second class these qualifications are required and something else—viz. the insight of the precis writer. The indexer must understand his subject and also understand the wants of the reader. The index must be exhaustive in its indication of the various points in the book, and concise in expression, and in addition the indexer must be careful in the choice of catchwords or titles for his headings. He must gather together the same subjects under one heading, and see that they are not separated under synonyms. An author frequently uses periphrases to escape from the repetition of the same fact in the same form; but these periphrases will give little information when inserted as headings in an index, and it is in this power of selecting the best catchword that the good indexer will show his superiority over the commonplace worker. The meaning of the word index has gradually grown from the general to the particular, and the word is now established as denoting a series of references arranged in alphabetical order. There are other kinds of indexes; but these require an explanatory adjective, as classified, chronological, &c. In indexing names it is most important to specify the cause of reference, as a block list of references after a name is almost useless. A colossal instance of this fault will be found in Ayscough's index to the Gentleman's Magazine, where all the references under one surname are placed together without even the distinction of the Christian name. There are 2411 entries under Smith, and it has been calculated that to go through this mass in order to find say Zachary Smith would take the consuler eight days of ten hours a day. It is also important to bring all the references to one man under one heading, and not to separate them under the different names or titles he may have borne. In the index to Scott's edition of Swift's Works there are 638 references to Harley, Earl of Oxford, arranged thus: 227 under Robert Harley, 111 under Lord Oxford, and 300 under Treasurer (Lord Oxford). There should be one index for a complete work and not a separate index for each volume. Again, no classification should be allowed in an alphabetical index. This vicious habit of classification makes the indexes of some well-known papers practically valueless. The consuler of the index wishes to find whether the volume contains anything on a particular subject, and he is only confused and annoyed if he has to look in a succession of alphabets arranged under such headings as original articles, notes, correspondence, &c. The preparation of an index consists of three divisions: (1) compilation, (2) arrangement, (3) printing. Each indexer will find out the mode of procedure which is most suitable for himself; but it may be said generally that foolscap paper is the most convenient size for use. Those entries which are not likely to be repeated can be written down on the page as they occur; but in the case of large headings it will be more convenient to use a separate page for each, and keep these pages in an alphabetised guard book so that they can be turned to in a moment. When the time comes to cut up the index and arrange it in alphabetical order, it will be necessary to see that there are no repetitions of the same subjects under various synonyms. Now is the time to make the cross references, and here considerable judgment is required. When the entries are short and few, it is better to repeat them than to refer from one to the other; but in the case of long entries cross references are very advantageous, and it is always well to refer to cognate headings. No reference to the contents of a general heading which is without subdivision should be allowed. If a general heading is divided into sections, and each of them is clearly defined, they should be 'cross-referenced,' but not otherwise. When the arrangement of the cut-up slips is undertaken, some alterations and revision of headings will frequently be found advisable. The value of an index is greatly enhanced by the proper setting out of the entries with judicious use of different types. When a book is a complete treatise on a special subject, a well-made index will form an admirable key to the subject and be in itself intrinsically useful. Indexes may also be made with regard to a particular subject dealt with in a number of books.
The Index Society, to form a library of indexes, and to make indexes to important books, rare serials, &c., was founded in 1877, and subsequently incorporated with the British Records Society; their publications appear quarterly in the Index Library. The American Library Association Index (1893) indexed 3000 miscellaneous volumes. See books mentioned in the article BIBLIOGRAPHY, and H. B. Wheatley's How to Catalogue a Library (1890).