Abstract: A pneumatically operated submersible pump and method for operating the same including a housing having a chamber disposed therein. A first opening is positioned in the housing for permitting liquid to flow into the chamber. A seal is operatively disposed within the camber for selectively sealing the first opening. A source of compressed air is provided for supplying compressed air to the chamber. A discharge opening is positioned in the housing for withdrawing liquid from the chamber. A predetermined quantity of liquid initially flows into the chamber through the first opening for imparting movement to the seal means for subsequently sealing the first opening. Thereafter compressed air is supplied to the chamber which displaces the liquid through the discharge opening thereby releasing the seal for repeating a pumping operation by again permitting the predetermined quantity of liquid to flow into the chamber through the first opening.

Abstract: Photography, particularly, a method of modifying slide transparencies so as to eliminate distortion and to provide uniform illumination in oblique projection, for example, upon rear view screens.The method of modifying slide transparencies includes supporting the object to be photographed at an angle with respect to the optical path of the camera; selectively illuminating the object to be photographed such that the portion farthest from the camera receives the greatest portion of the light with the rest of the object being gradually and continuously less illuminated so the portion nearest the camera receives the least light; and, taking a picture of the object, such that the transparency defines the object being photographed in trapezoidal form with the wider base being the least illuminated and the narrow apex being the greatest illuminated.