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From 1913, another of Copeman's inventions, a toaster with bread turner, was also produced by the Copeman Electric Stove Company. Electric toasters were a recent invention at that time - the first commercially successful version was patented in July 1909 - and the bread had to be turned manually once the first side had been toasted.
On September 16, 1930, Lehberger was issued U.S. patent #1,775,861. [232] 1930 Car audio. Car audio/video (car AV) is a sound or video system fitted in an automobile. In 1930, the Galvin Corporation introduced the first commercial car radio, the Motorola model 5T71, which sold for between $110 and $130 and could be installed in most popular ...
The Lower Paleolithic period lasted over 3 million years, during which there many human-like species evolved including toward the end of this period, Homo sapiens.The original divergence between humans and chimpanzees occurred 13 (), however interbreeding continued until as recently as 4 Ma, with the first species clearly belonging to the human (and not chimpanzee) lineage being ...
March 4, 1925 – President Coolidge begins full term, Dawes becomes the 30th vice president 1925 – Scopes Trial , whose outcome found that the teaching of evolution in the classroom "does not violate church and state or state religion laws but instead, merely prohibits the teaching of evolution on the grounds of intellectual disagreement"
The British physicist Dennis Gabor (1900–1979) invents holography. This method of recording and reproducing image with coherent light allows three-dimensional images. It was not until 1971 when the procedure gained practical importance, he received the Nobel Prize for Physics. 1949 In Germany, FM broadcasting starts regular program operation.
By 1950, his inventions were earning over $50,000 a year, enabling him to hire six assistants and investing $65,000 to convert his smithy into a machine and welding shop. [4] He also partnered with a local white man, Howard L. Rutter, who assisted him with distribution and marketing to white manufacturers and farmers beyond Lancaster. [ 7 ]
1900 – The Brownie camera is invented; this was the beginning of the Eastman Kodak company. The Brownie popularized low-cost photography and introduced the concept of the snapshot. The first Brownie was introduced in February 1900, [34] The first ascent of LZ1 over Lake Constance (the Bodensee) in 1900.
Hilbert's tenth problem is the tenth on the list of mathematical problems that the German mathematician David Hilbert posed in 1900. It is the challenge to provide a general algorithm which, for any given Diophantine equation (a polynomial equation with integer coefficients and a finite number of unknowns) can decide whether the equation has a ...