His first major theoretical contribution was On the electromagnetic theory of the reflection and refraction of light which he sent to the Royal Society in October 1878. Maxwell, in reviewing the paper, noted that FitzGerald was developing his ideas in much the same general direction as was Lorentz .
Kanyang unang major panteorya kontribusyon ay Sa electromagnetic theory ng pagmuni-muni at repraksyon ng mga ilaw na kung saan siya ay ipinadala sa Royal Society sa Oktubre 1878. Maxwell, sa pagrerepaso ng papel, tanyag na FitzGerald ay bumubuo ng kanyang mga ideya sa marami ang parehong bilang pangkalahatang dakong ay Lorentz.