Quantum-mechanical theory of stress and force.

A principal embodiment of the invention disclosed herein is a process for producing photographic slides which, as a consequence thereof, can be separately projected onto a screen in an overlapping manner with images common to both slides in precise registry. The process consists of preparing artwork, such as graphs, diagrams, charts and the like on a specially prepared format and photographing the work. The resulting film is then critically positioned in a device according to markings therein which correspond with markings on the format. The device known as a registration device constitutes another embodiment of the invention. The film is then punched and trimmed in the device, and thereafter mounted on a mask according to its markings whereupon the thusly mounted film is inserted in the usual carrier employed in slide projectors. The device, which is hereinafter designated a registration device, is deemed part of the invention. Alternatively, the invention comprehends slide carriers of unique construction in which the film that has been punched and scored for trimming in the registration device according to the process may be directly inserted into the carriers, the construction thereof being such that the step in the process of mounting the film onto a mask is eliminated.