A rotatable roll brush that despite combing tangled hair, the hair does not get removed due to the rotation of the brush body part, and when a combing action is required without the rotation of the body part, the brush can be converted and used as a regular brush. The electromagnetic flow meter has first and second detection resistors which are connected in series to ends of the exciting coil via the switching elements, respectively, wherein a midpoint of the first and second detection resistors is grounded to set a voltage of the midpoint as a circuit reference voltage. In another illustrative embodiment, a developed and highly innovative computer-enabled Internet-optimized academic credential model and processes, with academic integrity, for existing or new programs at regionally and nationally accredited and other postsecondary, higher education institutions is provided. A controller controls the charge transfer time of the line sensor at which the picked-up line image is transferred between each pair of adjacent pixel rows provided in the line sensor in association with the moving speed of a stage for moving the sample.