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4.2.3 1920s. 4.2.4 1930s. 4.2.5 1940 ... The timeline of historic inventions is a chronological list of particularly important or significant technological inventions ...
The following articles cover the timeline of United States inventions: Timeline of United States inventions (before 1890), before the turn of the century; Timeline of United States inventions (1890–1945), before World War II; Timeline of United States inventions (1946–1991), during the Cold War
1920 Jungle gym The jungle gym, also known as monkey bars or climbing frame, is a piece of playground equipment made of many pieces of thin material, such as metal pipe or, in more current playgrounds, rope, on which children can climb, hang, or sit.
1870 Feather duster. A feather duster is an implement used for cleaning. It consists typically of a wooden-dowel handle and feathers that are wound onto the handle by a wrapped wire. In 1870, the original idea for the feather duster was conceived in a broom factory in Jones County, Iowa. A farmer brought a bundle of turkey feathers into the ...
By 1920, 254,000 miles (408,800 km) of standard-gauge railroad track had been laid in the United States, all of it owned or controlled by seven organizations. [45] The need to synchronize train schedules and the inefficiencies introduced by every city having its own local time, also led to introduction of Standard time by railway managers in 1883.
The First Industrial Revolution, which ended in the middle of the 19th century, was punctuated by a slowdown in important inventions before the Second Industrial Revolution in 1870.
1920: The first regularly operating radio station KDKA goes on air on 2 November 1920 in Philadelphia, USA. It is the first time electronics are used to transmit information and entertainment to the public at large. The same year in Germany an instrumental concert was broadcast on the radio from a long-wave transmitter in Wusterhausen.
Technical Revolution or Second Industrial Revolution (1870–1920) Scientific-technical revolution (1940–1970) Information and telecommunications revolution, also known as the Digital Revolution or Third Industrial Revolution (1975–2021) Some say we’re on the brink of a Fourth Industrial Revolution, aka “Technological Revolution” (2020s)