Not only was it fun to play, but the slot machine also outperformed its competition when it came to its payout ratio. The simple yet ingenious concept: a slot with three independently spinning reels and five symbols each - Horseshoes, Diamonds, Spades, Hearts and the eponymous Liberty Bell. At the time, American inventor Charles August Frey wowed the masses with a slot machine named “Liberty Bell”. Did you know: The success story of slot machines began towards the end of the 19th century.