▁place ▁between ▁ 2 1 ▁May ▁and ▁ 2 5 ▁October ▁ 1 9 2 5 . ▁The ▁International ▁Ex hib ition ▁of ▁H yd rop ower ▁and ▁Tour ism ▁focused ▁on ▁the ▁production , ▁transport ▁and ▁broadcast ▁of ▁electric ity ▁as ▁well ▁as ▁tour ism ▁which ▁was ▁the ▁No . ▁ 2 ▁economic ▁resource ▁in ▁the ▁Al ps ▁at ▁the ▁beginning ▁of ▁the ▁century . ▁During ▁the ▁exhibition , ▁a ▁flo od light ▁was ▁installed ▁at ▁the ▁top ▁to ▁light ▁the ▁buildings . ▁ ▁On ▁ 6 ▁September ▁ 1 9 2 5 , ▁the ▁exhibition ▁was ▁opened ▁by ▁Prime ▁Minister ▁Paul ▁P ain lev é , ▁Éd ou ard ▁Her ri ot ▁and ▁André ▁H esse . ▁The ▁same ▁day , ▁more ▁than ▁ 2 , 0 0 0 ▁visitors ▁reached ▁the ▁top ▁of ▁the ▁tower ▁by ▁using ▁the ▁two ▁elev ators ▁which ▁drop ▁them ▁off ▁to ▁the ▁orientation ▁platform ▁located ▁at ▁ ▁height . ▁At ▁l unch , ▁Her ri ot ▁and ▁H esse ▁went ▁down ▁last ▁and ▁got ▁stuck ▁in ▁an ▁elev ator , ▁and ▁the ▁tower ▁staff ▁did ▁not ▁notice , ▁creating ▁some ▁pan ic ▁among ▁the ▁police ▁services . ▁ ▁The ▁International ▁Ex hib ition ▁of ▁H yd rop ower ▁and ▁Tour ism ▁was ▁a ▁success . ▁More ▁than ▁one ▁million ▁persons ▁came ▁to ▁the ▁city ▁of ▁ 8 5 , 0 0 0 ▁inhabitants , ▁which ▁got ▁benefits ▁in ▁spite ▁of ▁the ▁huge ▁works ▁undert aken . ▁ ▁In ▁ 1 9 2 9 , ▁an