RECORDING, PLATE-MEASURING SYSTEM FOR THE ULTRACENTRIFUGE.

Abstract We describe a system appropriate for measuring photographs from ultracentrifuge, free diffusion, or electrophoresis experiments recorded with schlieren or interference optics. The main parts are commercially available. Cartesian coordinates of significant features of the photographs are converted to digital form by means of decimal digital encoders attached to the two lead screws of a two-coordinate measuring microscope. The lead screw positions are continuously displayed on lampbank indicators. On command, the readings are automatically typed, punched into paper tape, or both. Identifying information and supplementary data for computation can be inserted as needed in the typed record or also in the tape. When coordinate readings are wanted at predetermined equal intervals, the abscissa ( x ) lead screw is advanced automatically to the successive positions at which measurements of the ordinate ( y ) are wanted. At present, for schlieren records, adjustment of the y lead screw and initial adjustment of the x lead screw are made manually with visual inspection of the projected image. This system increases the rate at which plates can be measured, completely avoids human error in writing down and transcribing measurements, and records measurements in forms convenient for evaluation either by electronic digital computation or by more usual methods.