Refraction

is the diversion of a ray of light which occurs when it falls obliquely on the surface of a medium differing in density from that through which it had previously moved. The differently-coloured rays have different degrees of refrangibility. Refraction is the cause of the phenomena of the mirage, Fata Morgan a, ., and presents to us the light of the sun before his actual emergence above the horizon. IMG:6949005855195395773_fig_579.jpg: Fig. 579. Regals or Portable Organ.