▁again ▁redis cover ed ▁in ▁ 1 9 5 5 ▁by ▁Henri ▁Am ar , ▁who ▁subsequently ▁wrote ▁in ▁ 1 9 5 7 ▁in ▁American ▁Journal ▁of ▁Physics : ▁" I ▁regret ▁my ▁un famil iar ity ▁with ▁South ▁American ▁literature ▁and ▁wish ▁to ▁acknow ledge ▁the ▁priority ▁of ▁Professor ▁Lo ed el ' s ▁work ", ▁along ▁with ▁a ▁note ▁by ▁Lo ed el ▁Pal um bo ▁cit ing ▁his ▁publications ▁on ▁the ▁geomet rical ▁representation ▁of ▁Lor ent z ▁transformations . ▁Those ▁diag rams ▁are ▁therefore ▁called ▁" Lo ed el ▁diag rams ", ▁and ▁have ▁been ▁c ited ▁by ▁some ▁text book ▁authors ▁on ▁the ▁subject . ▁ ▁Suppose ▁there ▁are ▁two ▁col linear ▁veloc ities ▁v ▁and ▁w . ▁How ▁does ▁one ▁find ▁the ▁frame ▁of ▁reference ▁in ▁which ▁the ▁veloc ities ▁become ▁equal ▁spe eds ▁in ▁opposite ▁directions ? ▁One ▁solution ▁uses ▁modern ▁algebra ▁to ▁find ▁it : ▁Suppose ▁ ▁and ▁, ▁so ▁that ▁a ▁and ▁b ▁are ▁rapid ities ▁corresponding ▁to ▁veloc ities ▁v ▁and ▁w . ▁Let ▁m ▁= ▁( a ▁+ ▁b )/ 2 , ▁the ▁mid point ▁rapid ity . ▁The ▁transformation ▁▁▁ ▁of ▁the ▁split - complex ▁number ▁plane ▁represents ▁the ▁required ▁transformation ▁since ▁ ▁and ▁ ▁As ▁the ▁ex ponents ▁are ▁add itive ▁in vers es ▁of ▁each ▁other , ▁the ▁images ▁represent ▁equal ▁spe eds ▁in ▁opposite ▁directions . ▁ ▁Publications ▁ ▁F ís ica ▁Element al , ▁E str ada ▁Editor ial , ▁Argentina ▁( 1 9 4 1