GROUND GLASS PLATES.--Dry plates used principally for making positive transparen cies. The emulsion is spread upon ground glass instead of plain, and this obviates the necessity of framing a piece of ground glass with the picture, a protective glass only being required.
GROUP.—In art, the term is used to signify the union of several figures, or of various material objects, placed in contact with each other for the purpose of forming a single group. Robinson, in his " Pictorial Effect in Photography," says: "The great art in the composition of a group is in so arranging the figures that they shall have some relation to each other, as well as the ordinary elements of pictorial construction. There should be some bond of union between those who compose the group, some incident should be repre sented in which they are mutually interested, or something must be imagined out of the picture to attract the attention of both, if only two are represented, or of many of them if there is a number. The figures should be massed together, and not scattered over the picture, so as to make it
necessary to examine each portrait in detail, until it has been seen and the effect agreeably felt as a whole. . . . When the picture is larger than carte de visite or cabinet size, it is always better and much easier to produce a group by combination printing. To accomplish this, a sketch should be made of the composition, no matter how roughly done, so that the artist knows what is intended by it, or the figures may be placed in position, and a small photograph taken of the arrangement. They should be so grouped that the joining should come in unimportant places. When a sketch or small photograph is made, the groups or single figures should be photographed in detail by preference against a white or very light screen if a background is also to be put in."