A pen is a tool used for writing or drawing with a colored fluid, such as ink. A ballpoint pen is a pen that uses a small rotating ball made of brass, steel or tungsten carbide to disperse ink while we write.

A posible classification of this system is:



Ability: to Write.
Cause of ability: Ball, Tip, Ink tube.

Ability: to Use / to Operate
Cause of ability: Hull (plastic or metallic tube), Rubber handle (sometimes).

Ability: to Keep
Cause of ability: Cap, pocket flap, retractable system : Button, bring.

The sketch was discovered in the 1960s when Leonardo's "Codex Atlanticus" was restored. It probably was drawn about 1493, almost 400 years before the bicycle was actually invented, That said the literary historian Augusto Marinon, the man that show the draw.
Although the Historians say no chain-driven, pedal-powered two-wheeler was built with the tools and materials of Leonardo's time, but Marinon beleves it possible: "... Leonardo envisioned such a vehicle. He had drawn other gear and chain mechanisms, and his spring-driven wagon was a forerunner of the modern automobile."

Some historians suggest the bicycle sketch is a fake and I think the same.

Text of a paper presented at the 8th International Conference on Cycling History, Glasgow School of Art, August 1997
Prof. Dr. Hans-Erhard Lessing

News of a bicycle-like sketch said to have been discovered during the ten-year restoring period of Leonardo da Vinci’s Codex Atlanticus popped up in 1974, when literary historian Augusto Marinoni gave a lecture in Vinci, Leonardo’s birthplace. From the chronology of disclosures and (in part circumstantial) evidence, it is now becoming clear that we are dealing with a recent forgery.

Popular credit for developing the modern bicycle usually goes to father and son Pierre and Ernest Michaux. Their 1860s two-wheeled velocipede had cranks and pedals connected to the axle of the front wheel, like children's tricycles of today.