The Collaborative International Dictionary of English v.0.48:

photodrome \pho"to*drome\ (f[=o]"t[-o]*dr[=o]m), n. [Photo- +
   Gr. dramei^n to run.] (Physics)
   An apparatus consisting of a large wheel with spokes, which
   when turning very rapidly is illuminated by momentary flashes
   of light passing through slits in a rotating disk. By
   properly timing the succession of flashes the wheel is made
   to appear to be motionless, or to rotate more or less slowly
   in either direction.
   [1913 Webster]