Sep 18, 1752: Adrien-Marie Legendre, French mathematician who contributed to number theory, celestial mechanics and elliptic functions, was born.

Sep 18, 1819: French physicist, Jean-Bernard-Léon Foucault was born. Using a long pendulum that would swing for many hours, Foucault directly proved that Earth rotates on its axis. The plane under the pendulum rotated, relative to the pendulum, at a rate related to the latitude of the site and Earth’s angular velocity. He made accurate measurements of the velocity of light. He proved that light travels slower in water than in air. He invented an accurate test still used today to measure the spherical and chromatic aberrations of lenses and telescope mirrors.

Sep 18, 1830: On this day, the first railroad locomotive built in the U.S., B&O locomotive Tom Thumb, the first locomotive built in America, lost a 14 kilometer race with a horse due to a boiler leak.

Sep 18, 1831: German-Austrian inventor, Siegfried Marcus, was born. He built four of the world’s first gasoline powered automobiles. He first began working on self-propelled vehicles in 1860. He made many inventions including an electric lamp, a carburetor, and an igniter for explosives. He also taught physics.

Sep 18, 1839: John Aitkin, Scottish physicist and meteorologist, John Aitkin is born. He’s know for his studies on atmospheric dust, the formation of dew, cyclones and evaporation. He invented instruments to study dust particles. Most importantly, Aitkin determined that condensation of water vapor from the air begins on the surface of microscopic particles, now called Aitken nuclei. This is critical to the formation of dew and rain.

Sep 18, 1895: Daniel David Palmer gave the first chiropractic adjustment to Harvey Lillard in Davenport, Iowa – now the home of Palmer Chiropractic College.

Sep 18, 1907: U.S. physicist Edwin Mattison McMillan was born. McMillan shared the 1951 Nobel Prize in Chemistry with Glenn T. Seaborg for their discovery of element 93, neptunium. Uranium is the heaviest naturally occurring element (92). By bombarding uranium with fast neutrons or deuterons, isotopes of the first element (93) beyond uranium were produced at a laboratory at UC Berkeley. By 1940, McMillan, Seaborg, and other colleagues found that the radioactive decay of neptunium produced element 94, which they named plutonium.

Sep 18, 1927: Columbia Phonograph Broadcasting System, the first radio network, first went on the air with 47 radio stations. The radio network lost money in its first year. On Jan 18, 1929, Columbia sold out to a group of private investors for $400,000, headed by William S. Paley, a Philadelphia cigar manufacturer. The radio network was renamed The Columbia Broadcasting System (CBS).

Sep 18, 1980: Cuban cosmonaut Arnaldo Tamayo-Mendéz became the first person of color and the first Latin American to fly into space. He flew on Soyuz 38, one of two men comprising the seventh international crew of the Intercosmos program. Tamayo-Mendéz spent several days aboard the Soviet space laboratory Salyut 6. He engaged in several experiments and measured the speed at which sugar crystals grow in space.