Today is the birthday of Jacques Charles, born in 1746, he constructed the first hydrogen balloons in 1783, and went up several times, reaching a height of over a mile. He repeated the work of Guillaume Amontons in 1787 and showed that different gases all expand by the same amount with a given rise in temperature. He was the first to make an accurate estimate of the degree of expansion, 1/273 per degree C. he did not publish his experiments and in 1802 Gay-Lussac also a balloonist published his same observations so that is why it is sometimes called Gay-Lussac’s Law.
Today is the birthday of John Rayleigh, born in 1842, he received the Nobel Prize for his discovery of argon. He wrote a textbook called the theory of sound which is still used today. He also discovered the phenomena of Rayleigh scattering, explaining why the sky is blue.