The U.S. Naval Observatory is building a measuring machine which will hold four PSS plates simultaneously and will automatically measure them, in a highly controlled environment, in about 12 hours. The images will be recorded by two camera subsystems with a scale of 0.9 arcseconds/pixel on a 0.33 × 0.26 degree CCD frame. The original glass plates of the PSS-II and glass copies of the PSS-I will be measured. This is a joint CALTECH-USNO program.