After graduation from Yale in 1910, Hammond took a job in the U.S. Patent Office. His strategy was simple: having learned from Edison that "inventing had to be a money-making proposition, where better to learn what fields were up-and-coming than in the Patent Office?" After he became an authority on the patent process, he founded the Hammond Radio Research Laboratory on his father’s estate in Gloucester, Massachusetts. In total, he is credited with more than 800 foreign and domestic patents on more than 400 inventions (the exact number of inventions is vague due to how credit was listed on the forms) mostly in the fields of radio control and naval weaponry.