76 SPECIAL TOPICS IN THEORETICAL ARITHMETIC 147. In connection with the subject of time I may mention the movement for the use of a 24-hour clock (%), a movement intended to do away with the confusion between A.M. and P.M. This movement has already gaind some headway. The Twenty Four Hour Clock. A sixteen hour day divided as indicated (ยง 146), with a sexi- denal notation, has, it seems to me, distinct advantages over (*) See James Arthur, Time and its Measurement, p. 46, reprinted, 1909, from Popular Mechanics Magazine.,