THE PHILATECTOR, electric watermark detector.According to the instruction leaflet, it will effectively reveal watermarks in postage stamps. It does work, although the battery is not included. It was made by H & A Wallace (Philatelists) Ltd., Old Broad Street, London, EC2. Size 4.5" x 3" x 1.5". It comes in its original box with slide and supplementary 4 colour filters.