As part of the University of California exhibit, Science in the Service of Man, Astronomy is included with the physical sciences of Chemistry, Physics, and Geology. Since the exposition largely represents the products of the Western states, it seemed desirable that the astronomical exhibit should represent the work of the great Western observatories. It is gratifying to acknowledge the co-operation of the Lowell Observatory, the California Institute of Technology, the Mount Wilson Observatory, the Astrophysical Observatory of Canada, at Victoria, as well as the Lick Observatory. The character of the exhibit depended largely on the floor plan available. For Astronomy, a booth-like space with two walls, one approximately a semicircle and the opposite one a straight wall, was made available. In the center of the booth, mounted on a pedestal, is the celluloid model of the two-hundred-inch telescope, loaned by the California Institute of Technology. Surrounding the pedestal is an octagonal cabinet exhibiting transparencies of the great telescopes of the Western observatories. The south wall is devoted to our knowledge of the solar system. The relative dimensions of the planets are shown as small spheres, made of plaster of Paris, supported by brass rods from the wall. Below these are 14χ 17-inch transparencies of the moon, sun, the corona, sunspots, prominences, and planetary phenomena. On a pedestal at the center of the wall is a three-dimensional model showing the sun and its stellar neighbors within sixteen light-years. Cabinets in front of the wall contain specimens of meteorites. The north wall is devoted to stellar systems. On the center of the wall is a frame, four by ten feet, containing a mosaic map of the Milky Way, from Auriga to Scorpio, made from photographs by Dr. Frank E. Ross and Mary R. Calvert, of the Yerkes Observatory. Below the map are enlarged photographs