It will be noticed that in the case of references the word see is omitted. If the names to be referred to, which follow a colon, are printed in italic, or, in the case of a manuscript catalogue, are underscored with red ink, they will be clearly distinguishable without the word see, and a wearisome repetition will be avoided. In the case of cross-references at the end to some other heading [see also], it will be more convenient to use the word than to omit it.

Panizzi was an advocate for a Subject Index, or "Index of Matters," as he called it,[30] but he did not venture to recommend such a work officially to the trustees.[31] He was fully examined on this subject before the Commission in 1849, and he referred to a memorandum which he had submitted to the Council of the Royal Society when employed upon their catalogue. He there writes:—

"A catalogue of a library is intended principally to give an accurate inventory of the books which it comprises; and is in general consulted either to ascertain whether a particular book is in the collection, or to find what works it contains on a given subject. To obtain these ends, classed catalogues have been compiled, in which the works are systematically arranged according to their subjects. Many distinguished individuals in different countries have drawn up catalogues of this description, but no two of them have agreed on the same plan of classification; and even those who have confessedly followed the system of another person have fancied it necessary to depart in some particulars from their model.... Those who want either to consult a book, of which they only know the subject, or to find what books on a particular subject are in the library, can obtain this information (as far as it can be collected from a title-page, which is all that can be expected in a catalogue) more easily from an index of matters to an alphabetical catalogue than by any other means. Here also nothing is left to discretion as far as concerns order. Entries, being short cross-references, are in a great measure avoided; and repetitions, far from being inconvenient, will save the time and trouble of looking in more places than one in order to find what is wanted.... The plan which is proposed was adopted by Dr. Watt in his Bibliotheca Britannica, the usefulness of which work must be acknowledged by every one conversant with bibliography. That it would not be so useful had any systematical arrangement been followed seems undeniable. The vast plan of the Bibliotheca Britannica, however, did not allow its author to give, either to the titles of the books or to the index, that extent which ought to be given to both in the Catalogue of the Library of the Royal Society" (Minutes of Evidence, p. 704).

Although here Panizzi makes the sound remark that the information to be expected in a catalogue is that which is found in the title-page, he had previously expressed a considerably more comprehensive opinion. He wrote:—

"The catalogue of a library like that of the Royal Society should be as complete as possible; that is, it should give all the information requisite concerning any book which may be the object of inquiry. Whether a work be printed separately, or in a collection—whether it extend to the greater part of a folio volume, or occupy only part of a single leaf—no distinction should be made; the title of each should be separately entered. Hence every one of the Memoirs or papers in the acts of academies; every one of the articles in scientific journals or collections, whatever they may be, should have its separate place in the catalogue. Thus, for instance, all the letters in Hanschius' Collection should be entered in their proper places under the writers' names. It is only by carrying this principle to the fullest extent that a catalogue can be called complete, and a library, more particularly of books relating to science, made as useful as it is capable of being. This, however, would make a great difference in the expense, and take considerable time."

A little consideration will show that such an extensive principle of action could not be practically carried out, and we may well ask whether it would be advisable to adopt such a plan even if it could be carried out. We regret the waste of labour spent in cataloguing the same book over and over again, but how much greater would be the waste of labour and money if the managers of every library which contained the Philosophical Magazine thought it necessary to include the whole contents of that periodical in its catalogue! The labour of cataloguing these series is the work of bibliographers, and such valuable books of reference as the Royal Society Catalogue of Scientific Papers and Poole's Index of Periodical Literature are suitable for all libraries.

To return to the mode of carrying out a subject index, it may be again remarked that it is not necessary to follow the titles textually, and if the titles are so followed there can be no advantage in making the references longer than in Watt's Bibliotheca. In primary entries the titles must be accurately followed, but in references it is often much more convenient to dispense with the wording chosen by the author. Two books with totally different titles are often identical in subject, and the indexer saves the time of the consulter by realizing this fact and acting upon it.

I think that any one who compares the system adopted in the indexes to the Catalogues of the Library of the Athenæum Club and of the London Library with that of, say, the Catalogue of the Manchester Free Library, 1881, will at once see how much more readily the former can be used.