Portrait of the French physicist Augustin Jean Fresnel, 1788-1827. Fresnel qualified as an engineer but was temporarily removed from his government post in 1815 for supporting the Royalists against Napoleon. At this time he grew interested in the problem of light and conducted experiments that Young had done a decade before. He also performed new experiments on interference and polarisation effects, & showed that to explain the effects light must be in the form of transverse waves as Young and Huygens had suggested, rather than longitudinal waves, like sound. Fresnel applied his skills to the development of lenses for light-houses.