September 30th in stamps Babe Ruth, Hoover Dam, Jean Baptiste Perrin

Here are some events that happened on September 30th. It could be an event or a person that died or was born on that day

1870 Born: Jean Baptiste Perrin, French-American physicist and chemist, Nobel Prize laureate (d. 1942)

Jean Baptiste Perrin  (30 September 1870 – 17 April 1942) was a French physicist who, in his studies of the Brownian motion of minute particles suspended in liquids, verified Albert Einstein’s explanation of this phenomenon and thereby confirmed the atomic nature of matter (sedimentation equilibrium). For this achievement he was honoured with the Nobel Prize for Physics in 1926.

In 1895, Perrin showed that cathode rays were of negative electric charge in nature. He determined Avogadro's number (now known as the Avogadro constant) by several methods. He explained solar energy as due to the thermonuclear reactions of hydrogen.

After Albert Einstein published (1905) his theoretical explanation of Brownian motion in terms of atoms, Perrin did the experimental work to test and verify Einstein's predictions, thereby settling the century-long dispute about John Dalton's atomic theory. Carl Benedicks argued Perrin should receive the Nobel Prize in Physics; Perrin received the award in 1926 for this and other work on the discontinuous structure of matter, which put a definite end to the long struggle regarding the question of the physical reality of molecules.

Perrin was the author of a number of books and dissertations. Most notable of his publications were: "Rayons cathodiques et rayons X"; "Les Principes"; "Electrisation de contact"; "Réalité moléculaire"; "Matière et Lumière"; "Lumière et Reaction chimique".

Perrin was also the recipient of numerous prestigious awards including the Joule Prize of the Royal Society in 1896 and the La Caze Prize of the French Academy of Sciences. He was twice appointed a member of the Solvay Committee at Brussels in 1911 and in 1921. He also held memberships with the Royal Society of London and with the Academies of Sciences of Belgium, Sweden, Turin, Prague, Romania and China. He became a Commander of the Legion of Honour in 1926 and was made Commander of the Order of Léopold (Belgium).

In 1919, Perrin proposed that nuclear reactions can provide the source of energy in stars. He realized that the mass of a helium atom is less than that of four atoms of hydrogen, and that the mass-energy equivalence of Einstein implies that the nuclear fusion (4 H → He) could liberate sufficient energy to make stars shine for billions of years. A similar theory was first proposed by American chemist William Draper Harkins in 1915. It remained for Hans Bethe and Carl Friedrich von Weizsäcker to determine the detailed mechanism of stellar nucleosynthesis during the 1930s.

In 1927, he founded the Institut de Biologie Physico-Chimique together with chemist André Job and physiologist André Mayer. Funding was provided by Edmond James de Rothschild. In 1937, Perrin established the Palais de la Découverte, a science museum in Paris.

Perrin is considered the founding father of the National Centre for Scientific Research (Centre National de la Recherche Scientifique (CNRS)). Following a petition by Perrin signed by over 80 scientists, among them eight Nobel Prize laureates, the French education minister set up the Conseil Supérieur de la Recherche Scientifique (French National Research Council) in April 1933. In 1936, Perrin, now an undersecretary for research, founded the Service Central de la Recherche Scientifique (French Central Agency for Scientific Research). Both institutions were merged under the CNRS umbrella on October 19, 1939.

His notable students include Pierre Victor Auger. Jean Perrin was the father of Francis Perrin, also a physicist.

Stamp issued by Guyana depicting Jean Baptiste Perrin

1927 – Babe Ruth becomes the first baseball player to hit 60 home runs in a season.

George Herman "Babe" Ruth Jr. (February 6, 1895 – August 16, 1948) was an American professional baseball player whose career in Major League Baseball (MLB) spanned 22 seasons, from 1914 through 1935. Nicknamed "The Bambino" and "The Sultan of Swat", he began his MLB career as a star left-handed pitcher for the Boston Red Sox, but achieved his greatest fame as a slugging outfielder for the New York Yankees. Ruth established many MLB batting (and some pitching) records, including career home runs (714), runs batted in (RBIs) (2,213), bases on balls (2,062), slugging percentage (.690), and on-base plus slugging (OPS) (1.164); the last two still stand as of 2019. Ruth is regarded as one of the greatest sports heroes in American culture and is considered by many to be the greatest baseball player of all time. In 1936, Ruth was elected into the Baseball Hall of Fame as one of its "first five" inaugural members.

At age seven, Ruth was sent to St. Mary's Industrial School for Boys, a reformatory where he was mentored by Brother Matthias Boutlier of the Xaverian Brothers, the school's disciplinarian and a capable baseball player. In 1914, Ruth was signed to play minor-league baseball for the Baltimore Orioles but was soon sold to the Red Sox. By 1916, he had built a reputation as an outstanding pitcher who sometimes hit long home runs, a feat unusual for any player in the pre-1920 dead-ball era. Although Ruth twice won 23 games in a season as a pitcher and was a member of three World Series championship teams with the Red Sox, he wanted to play every day and was allowed to convert to an outfielder. With regular playing time, he broke the MLB single-season home run record in 1919.

After that season, Red Sox owner Harry Frazee sold Ruth to the Yankees amid controversy. The trade fueled Boston's subsequent 86-year championship drought and popularized the "Curse of the Bambino" superstition. In his 15 years with the Yankees, Ruth helped the team win seven American League (AL) pennants and four World Series championships. His big swing led to escalating home run totals that not only drew fans to the ballpark and boosted the sport's popularity but also helped usher in baseball's live-ball era, which evolved from a low-scoring game of strategy to a sport where the home run was a major factor. As part of the Yankees' vaunted "Murderers' Row" lineup of 1927, Ruth hit 60 home runs, which extended his MLB single-season record by a single home run. Ruth's last season with the Yankees was 1934; he retired from the game the following year, after a short stint with the Boston Braves. During his career, Ruth led the AL in home runs during a season 12 times.

During Ruth's career, he was the target of intense press and public attention for his baseball exploits and off-field penchants for drinking and womanizing. After his retirement as a player, he was denied the opportunity to manage a major league club, most likely due to poor behavior during parts of his playing career. In his final years, Ruth made many public appearances, especially in support of American efforts in World War II. In 1946, he became ill with nasopharyngeal cancer and died from the disease two years later. Ruth remains a part of American culture, and in 2018 President Donald Trump posthumously awarded him the Presidential Medal of Freedom.

1935 – The Hoover Dam, astride the border between the U.S. states of Arizona and Nevada, is dedicated.

Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. Originally known as Boulder Dam from 1933, it was officially renamed Hoover Dam, for President Herbert Hoover, by a joint resolution of Congress in 1947.

Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc., which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.

Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume (when it is full). The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.

US stamps depicting the Hoover Dam