Mendeleyev, D. Ivanovich
Mendeleyev taught chemistry at St. Petersburg University, where he discovered the periodicity of the chemical properties of the elements.
The periodic table became one of the most useful and important generalizations of chemistry and of all science. In Mendeleyev's lifetime several new elements, including gallium, scandium, and germanium, were found in nature, and their chemical behavior matched that predicted by Mendeleyev's periodic table.
In 1569 he invented a type of map for seamen with perpendicular longitudes and latitudes, the now famous Mercator projection. In addition, he made remarkably detailed and accurate maps of western and southern Europe, which he designed, engraved and published.
He also designed a 6-engine transport capable of carrying 18 tons and the Me 410, a fighter bomber. In 1944 he produced the Me 262, the world's first jet fighter flown in combat.
After the war he was at first forbidden to design aircraft, but in 1958 he received NATO contracts for co-production of aircraft and missiles.
With the help of his colleague Edward Morley he conducted the Michelson-Morley experiment. This experiment showed that there was no significant motion of the Earth relative to the ether *. This result later became the foundation of Einstein's Theory of Relativity.
(* The ether was a hypothetical medium in which light waves were supposed to travel. The notion of this medium eventually had to be abolished.)
Although best known for his invention of logarithms his other mathematical contributions include a mnemonic for formulas used in solving spherical triangles, two formulas known as Napier's analogies used in solving spherical triangles and other inventions.
He also found exponential expressions for trigonometric functions, and introduced the decimal notation for fractions.
Napier, however, will be remembered for making one of the most important contributions to the advance of knowledge. It was through the use of logarithms that Kepler was able to reduce his observations and make his breakthrough which then in turn underpinned Newton's theory of gravitation.
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