Isochronic Pendulum
  The classic simple pendulum is a device which works as a simple harmonic oscillator (S.H.M.) only approximately. The time period remains fixed as long as the amplitude is kept sufficiently small. This limitation makes it unsatisfactory choice for practical time keeping purposes. The question addressed in this paper is regarding the modifications that can be made to the pendulum so that its time-period is independent of amplitude. Though the idea is not new, it is shown using rigorous mathematics that if the length of the suspension is suitably controlled so as to have a cycloidal path for the bob, this can be achieved. 
Sumit Kumar
physics.class-ph