▁thr ill ▁machines ▁are ▁a ▁defining ▁feature ▁of ▁am usement ▁par ks . ▁Early ▁r ides ▁include ▁the ▁car ousel , ▁which ▁originally ▁developed ▁from ▁caval ry ▁training ▁methods ▁first ▁used ▁in ▁the ▁Middle ▁A ges . ▁By ▁the ▁ 1 9 th ▁century , ▁car ous els ▁were ▁common ▁in ▁par ks ▁around ▁the ▁world . ▁Another ▁such ▁ride ▁which ▁sh aped ▁the ▁future ▁of ▁the ▁am usement ▁park ▁was ▁the ▁roll er ▁co aster . ▁The ▁orig ins ▁of ▁roll er ▁co aster s ▁can ▁be ▁trac ed ▁back ▁to ▁ 1 7 th - century ▁Russia , ▁where ▁gravity - dri ven ▁attra ctions , ▁which ▁at ▁first ▁only ▁consisted ▁of ▁individual ▁s led s ▁or ▁c arts ▁r iding ▁freely ▁down ▁ch utes ▁on ▁top ▁of ▁spe cially ▁constructed ▁snow ▁s lop es ▁with ▁p iles ▁of ▁sand ▁at ▁the ▁bottom ▁for ▁bra king , ▁were ▁used ▁as ▁winter ▁le is ure ▁activities . ▁ ▁These ▁cru de ▁and ▁tempor arily ▁built ▁curios ities , ▁known ▁as ▁Russian ▁Mountains , ▁were ▁the ▁beginning ▁of ▁the ▁search ▁for ▁even ▁more ▁thr illing ▁am usement ▁park ▁r ides . ▁The ▁Columb ian ▁Ex position ▁of ▁ 1 8 9 3 ▁was ▁a ▁particularly ▁fert ile ▁testing ▁ground ▁for ▁am usement ▁r ides ▁and ▁included ▁some ▁that ▁the ▁public ▁had ▁never ▁seen ▁before , ▁such ▁as ▁the ▁world ' s ▁first ▁Ferr is ▁wheel , ▁one ▁of ▁the ▁most ▁recognized ▁products ▁of ▁the ▁fair . ▁In ▁the ▁present ▁day , ▁many ▁r