Where Do Inventions Come From?

On November 4, 1879, James Ritty of Dayton, Ohio received a patent for the "Ritty Incorruptible Cashier", the first cash register. Ritty ran a saloon in Dayton in which he billed himself as a "Dealer in Pure Whiskies, Fine Wines, and Cigars". Ritty's problem was that the hired help kept purloining the cash from the customers. Ritty needed a way to insure the money made it to the till. Except there wasn't any till, perhaps just a cash box. Recording transactions left a lot to be desired.

Ritty took a steamship to Europe in 1878. While aboard ship, he was shown a device that through the use of rotating disks could give a readout of the revolutionary speed of the propeller shaft. [This was most likely a modification of the planimeter which had been adapted to this purpose in about the same period]. When Ritty got home, he immediately set to work with his brother, John, who was a skilled craftsman to use the rotating disk idea to keep count of the money in each customer transaction. It took three prototypes to get it right but they finally did develop a successful machine. The first cash register had no cash drawer, just a clock-like dial [see picture above from the Smithsonian Instiution] and a bell to signal transactions. Ritty and his brother started a company to manufacture his invention but the going was slow and Ritty soon needed to spend his time on his saloon business. He sold the company to Jacob Eckert who formed the National Manufacturing Company. Eckert in turn sold the company in 1884 to John H. Patterson who changed the name to the National Cash Register Company. NCR, of course, exists to this day as a major player in the cash register and computer industry.

So my question: "Where do inventions come from?" Ritty seems to have invented nothing else in his life. Why would this seemingly common problem that every small businessman had to deal with stick with him in such a way that he would see a connection with the speed indicator of a ship's propeller shaft? What spark went off in his head that said he could convert the idea to a cash counter? Ritty didn't even have the technical skills to make his idea real. That was left to his brother.

Inventions are strange. The spark that creates an idea can be almost a mystical event, one that lies in the same realm as that of the great writer or composer. No one seems to be able to define where this spark of creativity comes from. But where would we be without it? Because of a propeller shaft speed indicator, the cash register...and later NCR...was born.