This Day In History : April 18

1986 United States

IBM Produces First Megabit Chip

In 1986, IBM manufactured the world's first megabit-chip, marking a significant advancement in semiconductor technology. This development paved the way for higher-capacity memory storage in computers. The achievement showcased IBM's leadership in the technology sector.

Also on This Day in History April 18

Discover what happened on April 18 with HISTORY's summaries of major events, anniversaries,
famous births and notable deaths.

Births on This Day, April 18
  • 1949 Charles Louis Fefferman

    American mathematician who received the Fields Medal in 1978 for his work in mathematical analysis.

  • 1911 Maurice Goldhaber

    Austrian-American physicist who devised an experiment to show that neutrinos always rotate in one direction (only counterclockwise).

  • 1907 Lars Valerian Ahlfors

    Finnish mathematician who was awarded one of the first two Fields Medals in 1936 for his work with Riemann surfaces.

  • 1838 Paul Émile Lecoq de Boisbaudran

    French chemist who developed improved spectroscopic methods which had recently been developed by Kirchhoff.

  • 1863 Hugh Longbourne Callendar

    English physicist who was famous for work in calorimetry, thermometry and especially, the thermodynamic properties of steam.

Deaths on This Day, April 18
  • 2003 Edgar Frank Codd

    British-American computer scientist and mathematician who laid the theoretical foundation for relational databases, for storing and retrieving information in computer records.

  • 1945 John Ambrose Fleming

    English electrical engineer who invented, and coined the name for, the diode—first thermonic valve (tube).

  • 1674 John Graunt

    English statistician who is considered by many historians to have founded the science of demography (statistical study of human populations).

  • 1845 Nicolas-Théodore de Saussure

    Swiss chemist and plant physiologist whose quantitative experiments on the influence of water, air, and nutrients on plants laid the foundation for phytochemistry.

  • 1802 Erasmus Darwin

    Prominent English physician, poet , philosopher, botanist, naturalist and the grandfather of naturalist Charles Darwin and the biologist Francis Galton.

1925

Woman's World Fair

In 1925, the first Woman's World's Fair in U.S. was officially opened in Chicago, Illinois, by Mrs. Calvin Coolidge. For eight days, it displayed women's progress in 70 industries.
1949

Ireland becomes an independent republic

April 18, 1949, Ireland officially became an independent republic, severing its last ties with the British Commonwealth. This change followed the Republic of Ireland Act, which came into effect on this date. The country then began to assert its sovereignty on the global stage.
1906

San Francisco Earthquake and Fire Devastates City

On April 18, 1906, a massive earthquake struck San Francisco, causing widespread destruction and igniting fires that ravaged the city. Nearly 4,000 people were killed, and 75% of the city was destroyed in the disaster.
1985

Japan Enacts Its First Patent Law

On April 18, 1885, Japan established its first modern patent law, the Patent Monopoly Act. This legislation marked the foundation of Japan's patent system, promoting innovation and safeguarding inventors' rights.
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