This paper investigates oscillating characteristics and cyclic mechanisms in several hydraulic jumps, with experimental study made of the hydraulic jumps under two periodically repeated flow conditions. The analysis shows that the vortex roll-up process is linked to fluctuations of the longitudinal location of the jump toe. The paper includes comments on those few works in literature which deal with the subject. Measurements were made of the time interval during which each type of hydraulic jump was present along with the surface profile elevations downstream of the roller. Results, oscillating characteristics and cyclic mechanisms are in agreement with the new concept of turbulence. Indeed, it has become increasingly evident that the organized periodic motion is superimposed on a background of random turbulence, with many flows containing eddies, vortices whose description is more influential than previously thought.