Charles Fey is the inventor of slot machines. His grandsons run a restaurant in Reno (called the Liberty Bell, I think) with display of many old-time slots. His machines were leased to bars, and paid-out in packs of gum (hense the fruit symbols -- cherries, etc.) Fey was afraid of having the mechanism of his machines copied, so he never sold, just leased. In a short period, one was stolen from a bar, and not much later, competing machines began to appear (though he did patent his devise).

Mechanical slots improved over the years, but was not until the 1960's that Bally came out with their electro-mechanical "Money Honey" slot that electronic slot revolution began. There's a casino in Virginia City that has interesting museum of slots thru the ages. There's also books & articles written on them Some pretty intersting stuff.