Today's lecture is about the history of the bicycle. The first bicycle, invented in the early 19th century, had no pedals and was pushed along by the rider's feet. It was called a 'hobby horse'. Later, in the 1860s, pedals were added to the front wheel, creating the 'velocipede'. This design was improved with the 'high wheeler' in the 1870s, which had a large front wheel for speed but was unstable. Finally, the 'safety bicycle' with two equal-sized wheels and a chain drive appeared in the 1880s, making cycling much safer and more popular.