by Chas. T. Bainbridge's Sons in Brooklyn. The author has never seen a chemical analysis of this board and cannot vouch for its freedom from injurious substances; in the collections where it has been used, however, it seems as yet to have done no harm. In mounting prints certain uniform sizes are used in most large collections. The advantages are obvious. In the first place, it is much easier and safer to store objects of uniform size; in addition, they are more easily exhibited, whether in separate frames or in a wall or desk case, and in loan exhibitions where prints from other collections are shown they are much more easily handled if all of similar sizes. It has been found convenient to use the following three sizes of mats: 14×18, 22×28 and 28×40. These give good proportions and most prints fit one of these sizes. The usual custom in mounting prints is to hinge together two pieces of board with linen tape or strips of linen cloth especially prepared. An opening is cut in the front board to show the print up to the margin of the plate. The backing board must be fairly thick, so as not to bend easily in handling, and to give real protection to the object mounted upon it. Rubbing is very harmful to the surface of prints, and the front board varies in thickness according to the value and size of the print and the amount of protec-
