  cm ▁wide , ▁and ▁ 2 7   cm ▁deep , ▁which ▁was ▁filled ▁with ▁water , ▁and ▁which ▁could ▁be ▁rot ated ▁( dep ending ▁on ▁the ▁experiment ) ▁about ▁a ▁vertical ▁or ▁a ▁horizontal ▁axis . ▁Sun ▁light ▁was ▁directed ▁into ▁the ▁water ▁through ▁a ▁system ▁of ▁l enses , ▁mirror s ▁and ▁ref lex ion ▁pr isms , ▁and ▁was ▁reflected ▁ 7 ▁times ▁so ▁that ▁it ▁travers ed ▁ 2 8 . 5 ▁m . ▁In ▁this ▁way , ▁a ▁ret ard ation ▁of ▁order ▁ ▁was ▁observable . ▁However , ▁also ▁Bra ce ▁obtained ▁a ▁negative ▁result . ▁Another ▁experimental ▁installation ▁with ▁glass ▁instead ▁of ▁water ▁( prec ision : ▁), ▁also ▁yield ed ▁no ▁sign ▁of ▁b ire fr ing ence . ▁ ▁The ▁absence ▁of ▁b ire fr ing ence ▁was ▁initially ▁interpreted ▁by ▁Bra ce ▁as ▁a ▁ref ut ation ▁of ▁length ▁contra ction . ▁However , ▁it ▁was ▁shown ▁by ▁Lor ent z ▁( 1 9 0 4 ) ▁and ▁Joseph ▁L arm or ▁( 1 9 0 4 ) ▁that ▁when ▁the ▁contra ction ▁hypothesis ▁is ▁maintained ▁and ▁the ▁complete ▁Lor ent z ▁transformation ▁is ▁employed ▁( i . e . ▁including ▁the ▁time ▁transformation ), ▁then ▁the ▁negative ▁outcome ▁can ▁be ▁explained . ▁Furthermore , ▁if ▁the ▁relativ ity ▁principle ▁is ▁considered ▁as ▁valid ▁from ▁the ▁out set , ▁as ▁in ▁Albert ▁Ein stein ' s ▁theory ▁of ▁special ▁relativ ity ▁( 1 9 0 5 ), ▁then ▁the ▁result ▁is