The purpose of a composite mounted slide is to show more than one view at the same time, with use of one projector. By this method portions of transparencies of related subjects are mounted together on one slide.
A great variety of mounting combinations and arrangements are possible. They will largely depend on the subject matter and need.
There are some considerations to make before taking the photographs, such as choice of field, i. e., horizontal or vertical; relationship of subject size, and similarity of lighting arrangement and of background color.
Procedures in Making the Composite Slide
Selection and planning before cutting each individual transparency is necessary. It is important that the cut be straight.
SMIALOWSKI A, VAILE S. Composite Mounting of Thirty-Five-Millimeter Color Transparencies. AMA Arch Ophthalmol. 1958;60(2):321-323. doi:10.1001/archopht.1958.00940080337022