The earliest traffic signal was installed outside a parliament building and worked by gas, with a officer tur it b hand. I exploded wit a mo and t idea w abandoned f half a cen. What brought it back was not the motor car alone but the discovery that a crossing controlled by a policeman could handle only one instruction at a time, while a lamp could hold a whole street still for as long as the other street needed.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.