Today is the birthday of Johann Loschmidt, born in 1821; he called himself Josef which was his middle name. He wrote a book in 1861 with over 300 two-dimensional representations of molecules, Chemische studien. He represented benzene with a circle four years before Kekule. He was the first to estimate the size of air molecules and propose a constant for measuring the number of gas molecules in a volume called the Loschmidt constant. He also proposed the Loschmidt paradox while working with his friend Ludwig Boltzman. I wonder how many people have ever heard of him, this is some pretty important stuff.
Nicolas Lacaille was also born on this day in 1713, an astronomer, originally studied theology, directed an expedition to the Cape of Good Hope to measure the moon’s parallax. He prepared a star map of the southern sky, discovered Alpha Centauri to be a double star and named the southern stars after astronomical instruments. He lived in poverty but gave away copies of his star maps to anyone who wanted one, he died in 1762 at the age of 49.