▁valid ity ▁of ▁the ▁relativ ity ▁principle ▁within ▁the ▁domain ▁of ▁elect rod ynam ics , ▁but ▁contrary ▁to ▁Po inc ar é , ▁Buch erer ▁even ▁assumed ▁that ▁this ▁implies ▁the ▁none x istence ▁of ▁the ▁a ether . ▁However , ▁the ▁theory ▁that ▁was ▁created ▁by ▁him ▁later ▁in ▁ 1 9 0 6 ▁was ▁incorrect ▁and ▁not ▁self - cons istent , ▁and ▁the ▁Lor ent z ▁transformation ▁was ▁absent ▁within ▁his ▁theory ▁as ▁well . ▁ ▁Lor ent z ' s ▁ 1 9 0 4 ▁model ▁▁ ▁In ▁his ▁paper ▁Elect romagnet ic ▁phen omena ▁in ▁a ▁system ▁moving ▁with ▁any ▁velocity ▁smaller ▁than ▁that ▁of ▁light , ▁Lor ent z ▁( 1 9 0 4 ) ▁was ▁following ▁the ▁suggestion ▁of ▁Po inc ar é ▁and ▁attempted ▁to ▁create ▁a ▁form ulation ▁of ▁Elect rod ynam ics , ▁which ▁explains ▁the ▁failure ▁of ▁all ▁known ▁a ether ▁dr ift ▁experiments , ▁i . e . ▁the ▁valid ity ▁of ▁the ▁relativ ity ▁principle . ▁He ▁tried ▁to ▁prove ▁the ▁applic ability ▁of ▁the ▁Lor ent z ▁transformation ▁for ▁all ▁orders , ▁although ▁he ▁didn ' t ▁succeed ▁completely . ▁Like ▁Wien ▁and ▁Abraham , ▁he ▁argued ▁that ▁there ▁exists ▁only ▁elect romagnet ic ▁mass , ▁not ▁mechanical ▁mass , ▁and ▁derived ▁the ▁correct ▁expression ▁for ▁longitud inal ▁and ▁trans verse ▁mass , ▁which ▁were ▁in ▁agreement ▁with ▁Kauf mann ' s ▁experiments ▁( even ▁though ▁those ▁experiments ▁were ▁not ▁precise ▁enough ▁to ▁distinguish ▁between ▁the ▁theories ▁of