=261. Sheaf Catalogue.=--The second form of manuscript catalogue is the _sheaf_, which may be described as a book-application of the principle of the card catalogue. It consists of a sheaf or holder in the shape of a book-cover which is fitted with locking rods designed to hold some 600 or 800 leaves. The leaves are separate individual pieces of paper cut to a standard size and punched with slots and holes to accommodate the locking rods of the sheaf. The sheaf is arranged on much the same plan as the card catalogue, except that several books are entered on each page as a rule, and when any page becomes congested it is re-written as a whole. It will be seen that this is the loose-leaf principle, which has largely become so prominent in business methodology; and, indeed, the sheaf-catalogue was undoubtedly the forerunner of the loose-leaf ledger. It has most of the advantages of the card catalogue, occupies less space, and has the undeniable advantage of book form; but whereas in the card catalogue there is little or no re-writing of entries, in the sheaf catalogue this must be undertaken at intervals. Of course if one page were devoted to each entry, as one card is so devoted in the card catalogue, the merits of the systems would seem to be equal, except perhaps that the card is of a more durable material than the paper used in the sheaf. But either card or sheaf is infinitely superior to any other form of MS. catalogue. A reference only is necessary to other forms of MS. which have been proposed from time to time, as none of them has been adopted by any number of libraries. The very old libraries occasionally use a slip catalogue; the Bodleian and British Museum, for example, paste slips into volumes or guard books resembling large scrap-books in approximate alphabetical order, and other libraries use similar methods. The system is a good one in many respects; the public understands and likes it; but the catalogue runs to so many large volumes that its accommodation would be a serious matter for the ordinary library; and the congestion of entries, with loss of all but approximate alphabetical order at most letters of the alphabet, will be obvious. Adjustments will be explained in the next chapter. It is not the intention here to recommend any special method or form of cataloguing; individual library systems have individual needs; and no librarian should make so important a decision as to the character of his catalogue without an examination of such catalogues as have been named and described. Our next chapter will illustrate the physical forms of catalogue sufficiently, we think, for most practical purposes. =262. Codes and Rules[9].=--Whatever form of catalogue is chosen, the main entry is practically the same for them all; that is, the author entry; and a whole literature of cataloguing rules and codes now exists which must receive careful attention. The principal of them are as follows: