What 1878 invention by a former slave do you use every day?

Before 1878, doors were secured with latches or leather straps that fastened onto wooden hooks. But 16-year-old Oswald Dorsey, who was born a slave and freed when he was 8 months old, had a better idea. He created and patented the doorknob. The mechanism in this device moved a rod that slid into the doorframe. It took years for people to embrace them fully and begin installing them on the doors in their homes.