As to the mechanics of catalogue-making, widely different usages and materials prevail. In America, the card or title-slip system is well nigh universal, while in England it is but slowly gaining ground, as against the ledger or blank book catalogue. Its obvious advantage lies in affording the only possible means of maintaining a strict alphabetical sequence in titles, whether of authors or subjects. The title-cards should be always of uniform size, and the measure most in vogue is five inches in length by three inches in breadth. They should not be too stiff, though of sufficient thickness, whether of paper or of thin card board, to stand upright without doubling at the edges. They may be ruled or plain, at pleasure, and kept in drawers, trays, or (in case of a small catalogue) in such paste-board boxes as letter envelopes come in. The many advantages of the card system, both for catalogues and indexes, should not lead us to overlook its palpable defects. These are (1) It obliges readers to manipulate many cards, to arrive at all the works of an author, or all the books on any subject, instead of having them under his eye at once, as in printed catalogues. (2) It can be used only in the library, and in only one place in the library, and by only one person at a time in the same spot, while a printed catalogue can be freely used anywhere, and by any numbers, copies being multiplied. (3) It entails frequent crowding of readers around the catalogue drawers, who need to consult the same subjects or authors at the same time. (4) It requires immeasurably more room than a printed catalogue, and in fact, exacts space which in some libraries can be ill afforded. (5) It obliges readers to search the title-cards at inconvenient angles of vision, and often with inadequate light. (6) It is cumbersome in itself, and doubly cumbersome to searchers, who must stand up instead of sitting to consult it, and travel from drawer to drawer, interfering with other searchers almost constantly, or losing time in waiting. (7) To this is added the inconvenience of constant insertion of new title-cards by members of the library staff, and the time-consuming process of working the rods which keep the cards in place, if they are used, and if not used, the risk of loss of titles, or misplacement equivalent to loss for a time.