In twelve of these compartments are arranged rollers, curtains, magnets, etc., as previously described, and a compartment through which a focusing lens is used. The two end compartments provide for the adjustment of the camera, which is supported in the box to the rear of the exposing arrangements. A cable of insulated wires for connecting the twelve magnets with the exposing motor, contains a wire for the return current. As seen in the engraving, seven of the magnets by the passage of their respective currents have completed their releasing operations. In the eighth compartment the two apertures in the exposing band are in the act of effecting an exposure. The remaining four magnets are awaiting their turn for action. Figure 5 is a photographic camera divided into thirteen compartments, each having a lens of the same construction, and the same focal length; these are arranged to correspond with the compartments in the electro-exposors. One of the lenses is provided with a focusing screen, and with it the other twelve lenses are adjusted to a proper focus without removing the plate holder behind them from its position in the camera. The plate holder is constructed to hold three dry plates, each three inches by twelve inches; the front is divided into twelve compartments, each three inches square. [Illustration: Fig. 5.] Light is excluded from the front by a roller blind, strengthened by thin narrow slats of hard wood; the blind works in grooves, is drawn over a concealed roller, and covers the back of the holder when the plates are being exposed. Figure 6 is a rear and side view of the circuit maker, conventionally called the exposing motor. The motive power is an adjustable weight attached to a cord which is wound around a drum. Twenty-four binding posts are attached to the table at the back of the exposing motor; other binding posts are arranged for return or other currents. Figure 7 illustrates a front and side view of the upper part of the exposing motor. Fastened to the frame is a ring of hard rubber, in which are inserted twenty-four insulated segments of platinum-coated brass; these segments are connected by insulated wires to the twenty-four binding posts on the back of the motor table, figure 6. [Illustration: Fig. 6.] A shaft, connected by an arrangement of geared wheels to the drum, passes through the center of the segmented ring and carries a loose collar; a stout metal rod is firmly attached near its longitudinal center to this loose collar. One arm of the rod carries a laminated metal scraper, or contact brush, arranged to travel around the periphery of the ring, and in its revolution to make contact with each segment in succession. The contact brush is connected through the arm with one pole of the battery; and each segment--through its independent wire and magnet of the electro-exposors--with the other pole. [Illustration: Fig. 7.] [Illustration: Fig. 7.]