Number 254 (Story #3), January 11, 1996 by Phillip F. Schewe and Ben Stein FRACTAL SCUM is what you get when you sprinkle a cloud of particles on a flowing fluid. Edward Ott and his colleagues at the University of Maryland, Johns Hopkins, and NRL observed the behavior of particles on the surface of a tank of water slowly being drained and replenished. When the drain is operated in a pulsed mode eddies form at the surface and the particles arrange themselves in a fractal pattern. That is, the patterns are self- similar at various size scales (Thomas M. Antonsen et al., Physical Review Letters, 6 November 1995). The researchers believe that their finding may help in the study of fluids in which flow patterns at many size scales are important. (New Scientist, 16 December 1995.)