4/15/1452 Leonardo Da Vinci artist, illegitimate child, lacked a classical education, vegetarian, dissected at least 30 cadavers, he kept most of his ideas to himself and wrote his notes in code, he painted the last supper, Mona Lisa, he died in 1519 at age 67.
4/15/1707 Leonard Euler mathematician, received his masters degree at age 16, lost the sight of his right eye by observing the sun, he later lost sight in the other eye, he was a prolific mathematician, introduced e for the base of the natural logarithm, i for the square root of -1 and f for function, he published a book on science in 1768 which was in print for 90 years, he died in 1783 at age 76.
4/15/1793 Friedrich Struve astronomer, studied double stars, prepared a catalog of 3112 of them in 1827, he died in 1864 at age 71.
4/15/1801 Edouard lartet paleontologist, one of the founders of modern paleontology, He found a fossil of a mammoth tooth that had a drawing of a mammoth on it, showing that intelligent humans were here when mammoths existed, he died in 1871 at age 70.
4/15/1874 Johannes Stark physicist The Stark Effect in 1913 showed a strong electric field would cause a multiplication in spectral lines. He supported Hitler and his racist views. A Noble Prize winner in 1919, he was tried and convicted as a Nazi in 1947. He died in 1957 at age 83.
4/15/1896 Nikolay Semenov chemist worked on chain reactions and thermal explosions, Theory of branched chain reactions, he died in 1986 at age 100.