Each sky-limited photographic plate taken with the U.K. 1.2 metre Schmidt telescope records about a million star and galaxy images. It is not feasible to measure these plates using manual machines, and this led to the development of COSMOS - an automatic machine capable of finding and measuring the Co-Ordinates, Sizes, Magnitudes, Orientations and Shapes of all the images on a single plate in less than a day. Information obtained from these measurements enables computer discrimination between star and galaxy images and hence quantitative studies of the properties and distributions of the two kinds of objects to be carried out. However, COSMOS is not restricted solely to astronomical problems and it has been used in the fields of topography and image restoration and enhancement. © 1980 D. Reidel Publishing Co.