This paper will review progress on the automated detection of variable objects on Schmidt plates, describe the various populations of variables which have been discovered, and summarise some of the most interesting results to date. So far, the searches have been based on sequences of a dozen or more sky limited UK 1.2m Schmidt plates taken on timescales from one day to several years. The plates were measured on the COSMOS measuring machine at the Royal Observatory, Edinburgh which typically detects between 100,000 and 200,000 images in the central 16 deg2 of each plate. The measures for each field are combined, and calibrated using deep electronographic sequences, to give data sets of some 100,000 objects, complete in the magnitude range B = 13–21. The procedure is described in some detail by Hawkins (1983a) and results in a sequence of magnitudes accurate to about 0.1m for each object in the measured area. Field effects across the plates are allowed for, and an extensive set of diagnostics allows the distribution of errors as a function of magnitude, and on each plate, to be monitored.