=278.= Various kinds of trays, described and figured below, are intended to replace the “cabinet” system; but it is clear that if every drawer is easily detached from a cabinet and if suitable table space is available their advantages are more theoretical than real. A good form, which is well safeguarded and not too heavy or clumsy, will be found in a tray which is provided with all necessary accessories in the form of locking-rod, guides, adjustable angle-block, outside label-holder, and felt pads to prevent it from scratching table-tops or other furniture. This kind of tray can be kept in racks of a convenient size, and users can remove it to a table for consultation. [Illustration: FIG. 98.--Cards for Bonnange Catalogue Trays (Section 279).] =279.= A French form of card-catalogue tray was invented by Mr F. Bonnange, of Paris, in 1866, and improved in 1874. In this, the method of securing the card differs from the rod threading through perforations, as in English and American models. The cards are hinged, and have shoulders formed in the slightly thicker lower portion, as shown in the illustration (Fig. 98), which is also slotted to clear the fastening. The hinged cards shoulder into side grooves formed in the wooden trays, and the slotted portion is placed astride a powerful endless screw, which traverses the tray from end to end, and carries a suitable block which acts as a travelling clamp. The screw is worked by means of a key, and when turned to the right the block travels forward along the screw till the cards are all firmly clamped between it and the end of the tray; when turned to the left the block travels back and so releases the cards to enable insertions to be made. The upper portion of the cards being hinged, and consequently free of the block, are not clamped, and can be turned over readily for purposes of consultation. Guides, alphabetical or numerical, may be inserted either above or at either side of the cards. [Illustration: FIG. 99.--Bonnange Card Catalogue Trays (Section 279).] =280.= An Italian card tray on a somewhat similar principle to this was invented by Mr A. Staderini, of Rome, in 1890. It differs from the Bonnange tray in having a sliding-block gearing with a ratchet which is fastened along the bottom and made to engage or disengage with a key. The cards are similar in principle to those of the Bonnange system, save that the lower hinged half is not slotted. The illustration (Fig. 100) will explain better than words the appearance and other accessories of this tray. [Illustration: FIG. 100.--Staderini Card Trays and Hinged Card (Section 280).]