Blaise Pascal was a French physicist, mathematician, philosopher, and inventor. A child prodigy, Pascal's work on projective geometry, at the age of 16 is commendable. He is one of the earliest inventors of the mechanical calculator, which he did when he was still a teenager. His work on probability theory influenced the development of social science and modern economics.
Rudolf Diesel was a German mechanical engineer and inventor best remembered for inventing the Diesel engine. After Diesel's demise, his engine became an important substitution for the steam piston engine. The engine became widespread in applications, such as agricultural machines, submarines, ships, and trucks. His life inspired the 1942 biographical film Diesel, in which he was played by Willy Birgel.
Nicéphore Niépce revolutionized science by inventing heliography and made the first permanent photographic image. He had initially been part of Napoleon’s army but had to quit due to his failing health. The Niépce Prize is awarded to a photographer every year in France, in his honor.
Known for his pathbreaking Gay-Lussac's Law, French chemist-physicist Joseph Louis Gay-Lussac was also the first, along with his colleague Alexander von Humboldt, to discover that water is composed of one part of oxygen and two parts of hydrogen. His name is one of the 72 that adorn the Eiffel Tower.
Augustin-Jean Fresne, best remembered for his pioneering research on the wave theory of light, was a sickly child and was mostly homeschooled in his early days. The French physicist was a civil engineer, too. Unfortunately, most of his scientific work failed to receive public attention during his lifetime.