Jan Ingenhousz

Hello! My name is Jan Ingenhousz. I was born a long, long time ago, on December 8th, 1730, in a town called Breda in Holland. Even as a little boy, I was very curious. I loved asking questions and learning how things worked. I studied hard and grew up to become a doctor so I could help people feel better.

As a doctor, I wanted to stop a sickness called smallpox. It was making many people very ill. In 1765, I moved to London, England, to learn a new way to protect people. The idea was to give someone a tiny, safe piece of the sickness so their body could learn how to fight it off. It worked! I helped many people stay healthy. While in London, I met other curious people, like the famous American scientist, Benjamin Franklin. We loved talking about science and new ideas.

My work became so well-known that in 1768, the Empress of Austria, a very important ruler named Maria Theresa, asked me to come to her palace in Vienna. She wanted me to protect her whole family from smallpox. It was a very big job, but I was happy to help. I stayed there for many years, making sure the royal family was safe and healthy.

Even while I was a busy doctor, I never stopped being curious. I became fascinated by plants! Another scientist, Joseph Priestley, had discovered that plants could make air fresh again, but I wanted to know how. In 1779, I did many experiments. I put plants in water and watched them closely. I discovered something amazing! In the sunlight, the green parts of plants released bubbles of a special air that we need to breathe. But in the dark, they didn't. I realized that plants need sunlight to make the fresh air that all animals and people depend on. It was their secret recipe!

I spent the rest of my life exploring the world and conducting experiments. I lived to be 68 years old. Today, people remember me for discovering the secret of plants. The process I found is called photosynthesis, and it's one of the most important processes on Earth. Every time you take a deep breath of fresh air, you can thank the green plants and the sunlight for working together, just like I discovered.