▁present ▁the ▁latest ▁in ▁science ▁and ▁technology . ▁Thomas ▁Ed ison ▁visited ▁the ▁Ex position ▁to ▁visit ▁a ▁pav il ion ▁devoted ▁to ▁his ▁recent ▁invent ions , ▁including ▁an ▁improved ▁ph on ograph ▁with ▁clearer ▁sound ▁quality . ▁▁ ▁Another ▁new ▁technology ▁that ▁was ▁promoted ▁at ▁the ▁Ex position ▁was ▁the ▁safety ▁elev ator , ▁developed ▁by ▁a ▁new ▁American ▁company , ▁Ot is ▁E lev ator . ▁Ot is ▁built ▁the ▁elev ators ▁carrying ▁passengers ▁up ▁the ▁legs ▁of ▁the ▁E iff el ▁Tower ▁to ▁the ▁first ▁level . ▁When ▁journal ists ▁expressed ▁concern ▁about ▁the ▁safety ▁of ▁the ▁elev ators , ▁Ot is ▁techn icians ▁filled ▁one ▁elev ator ▁with ▁three ▁thousand ▁kil og rams ▁of ▁lead , ▁sim ulating ▁passengers , ▁and ▁then , ▁with ▁journal ists ▁from ▁around ▁the ▁world ▁watching , ▁cut ▁the ▁cable ▁with ▁an ▁ax e . ▁ ▁The ▁elev ator ' s ▁fall ▁was ▁halt ed ▁ten ▁feet ▁above ▁the ▁ground ▁by ▁the ▁Ot is ▁safety ▁bra kes . ▁ ▁There ▁were ▁pav il ions ▁especially ▁devoted ▁to ▁the ▁tele phone ▁and ▁to ▁electric ity , ▁and ▁others ▁devoted ▁to ▁mar itime ▁navigation , ▁and ▁another , ▁the ▁Pal ais ▁de ▁Guerre ▁or ▁Palace ▁of ▁War , ▁to ▁develop ments ▁in ▁military ▁technology , ▁such ▁as ▁naval ▁art illery . ▁▁▁ ▁Pref ab ric ated ▁metal ▁housing ▁was ▁another ▁technology ▁that ▁appeared ▁at ▁the ▁Ex position . ▁ ▁Gust ave ▁E iff el ▁developed ▁a ▁series ▁of ▁houses ▁with ▁roof ▁and ▁walls ▁of ▁gal