Abstract: A refrigerating method and system using compressed, filtered, dehumidified, turbo expanded and re-circulated air for the enclosed refrigerated environment. Compressed air passes via a series of moisture-removal devices (12, 24, 32), dust filter (52), heat exchanger (60), turbine expander (65), impeller fan (92), vacuum refrigeration chamber (70) and muffler (98).

Abstract: A universal dual power telescope comprises two concentrically mounted telescopes combining functions of a tube-mounted finder and a regular telescope. The finder rotating inside the telescope includes a truncated prism for switching the telescope modes of operation. The dual function prism reflects images into the eyepiece either through the finder or telescope, while deflecting light rays and blocking formation of images through the other non-selected optical assembly. Both telescopes share the same eyepiece and focusing system. A low magnification finder or a high magnification telescope can be selectively engaged by changing an angular position of the prism's silvered plane.