Before there were alarm clocks, how did people wake up at a specific time they wanted to in the morning? Since the Industrial Revolution began in the 1780s, people had been finding ways to make sure they got to work on time. Back then, a knocker-up, also known as a "knocker-upper," started as a profession to wake people up by knocking on their doors or windows. Even though alarm clocks had been invented in 1787 by American inventor, Levi Hutchins, they were not yet available to the general public in Britain or Ireland. It was common for people in these places to hire knocker-ups to wake them up in the morning. Half a century after the invention of alarm clocks, Frenchman Antoine Redier patented an adjustable alarm clock in 1847. Still, mechanical alarm clocks were not cheap or widely available. Well into the 1920s, most workers in Britain would rather hire knocker-ups. Knocker-ups used a variety of methods to wake up their clients. Some used a baton, or a short, heavy stick, to knock on the client's door. Some used a long and light stick made of bamboo to reach the client's window on a higher floor. Still others used a pea-shooter, through which small objects can be blown, to shoot dried peas at their clients' windows. Their job was to rouse the sleeping clients, and they certainly came up with creative ways to achieve this goal. Knocker-ups would not leave a client's door or window until they made sure that the client had been awaken. There were large numbers of people carrying out the job, especially in large industrial towns such as Manchester. Knocker-ups were generally elderly men and women, but sometimes police officers would take on the job to earn extra income by performing the task during early morning patrols. But who woke the knocker-uppers? A tongue-twister from the time goes like this: We had a knocker-up, and our knocker-up had a knocker-up And our knocker-up's knocker-up didn't knock our knocker up So our knocker-up didn't knock us up 'Cos he's not up. By the 1950s, knocking up had gradually died out in most places due to the wide spread of electricity and affordable alarm clocks. Today, people merely read about anecdotes regarding how knocker-ups woke up their clients creatively or a fun tongue-twister like the one above.