52 The Library. must ask you to look at this illustrated specification and under- stand it for yourselves. I may say that the cost of providing hinged discs or slats of metal or card board in the elaborate shapes devised by Mr. Dunlop would be enormous. The main feature of the invention is, I think, the means given by the long slot cut in the lower part of the plates for lifting the entry wanted above the level of the tray and folding it back for convenience of refer- ence. I cannot say if this invention has ever been put into operation, but should be glad to receive information on the point. This is a drawing of another tray invented by Dr. Carl Dziatzko in 1879, while he was librarian at Breslau. His successor, Professor Staender, made various minor improvements and it is largely used in Germany, Austria and Switzerland. The main feature, as you will observe, is the broad brass bar passing over the cards to keep them in place. It is necessary to secure the block tightly when the tray is not full of cards, other- wise it is easy to slip a card up under the bar. A similar prin- ciple has been several times applied to cabinets and trays, the main difference being that rods or stout wires are used instead of flat bars. The French model to which I referred was first described in 1866, and afterwards made in an improved form in 1874. The inventor, Mr. F. Bonnange, of Paris, is the originator, so far as I can ascertain of the hinged card, and those of you who were at Paris in 1892, or have visited any of the large Paris or other French libraries, must have seen this style of tray " Card " catalogue. I have been unable to obtain a model from Mr. Borgeaud, the maker, but I can show you an almost identical Italian device, which was introduced by Mr. Staderini of Rome, over ten years ago. The Bonnange tray is similar in principle to this, save that, instead of a sliding block gearing with a ratchet, it has a powerful endless screw worked by a key, on which a block travels as required. The hinged cards shoulder into the side-groves, as in the Staderini system, but there is also a large slot cut to enable the cards to be placed astride of the screw without resting on it. When the key is turned to the right the block travels along till the cards are all firmly clamped ; when turned to the left the cards are released. A feature of some little importance possessed by both the Bonnange and Staderini u Bonnange (F.) : Nouveau systeme de catalogue au moyen de cartes. Paris, 1866.
