Patent Model of Edison's Universal Stock Printer, circa 1872

Thomas Edison's reputation was initially established through his work in telegraphy, particularly on stock tickers -- telegraphs that printed real-time financial information. While he did not invent the stock ticker, his improvements -- particularly those related to synchronizing multiple units -- were a great commercial success. Edison's experience with telegraphy infrastructure, and his approach to continually refining his designs, was foundational for his later successes.