| APRIL 20 - BIRTHS | |
| Gerald S. Hawkins | |
(source) |
 Born 20
Apr 1928; died 26 May 2003.
Gerald Stanley Hawkins was an English astronomer and mathematician who identified Stonehenge to be a prehistoric astronomical observatory. He identified 165 key points in the Stonehenge complex and found that many of them very strongly correlated with the rising and setting positions of the sun and moon. He used a computer to show that there existed at Stonehenge a pattern of alignments with twelve major lunar and solar events. He first published his findings in an article, Stonehenge Decoded, in the journal Nature (1963), and then in a book with the same title (1965). In Beyond Stonehenge he explored the mysteries of Machu Pichu, the Nasca Lines, Easter Island and the Egyptian Temples of Karnak and Amon-Ra. |
| Karl Alex Müller | |
(source) |
Born 20
Apr 1927
Swiss physicist who, along with J. Georg Bednorz, was awarded the 1987 Nobel Prize for Physics for their joint discovery of superconductivity in certain substances at higher temperatures than had previously been thought attainable. They startled the world by reporting superconductivity in a layered, ceramic material at a then-record-high temperature of 33 degrees above absolute zero. Their discovery set new research worldwide into related materials that yielded dozens of new superconductors, eventually reaching a transition temperature of 135 kelvin. |
| Kai Manne Börje Siegbahn | |
| Born 20
Apr 1918
Swedish physicist, corecipient with Nicolaas Bloembergen and Arthur Leonard Schawlow of the United States of the 1981 Nobel Prize for Physics for their revolutionary work in spectroscopy, particularly the spectroscopic analysis of the interaction of electromagnetic radiation with matter. |
|
| Joseph Wolpe | |
(source) |
Born 20
Apr 1915; died 4 Dec 1997.
South African-born American psychotherapist who helped usher in cognitive behavioral therapy during the 1960s; he devised a treatment to help desensitize patients with phobias by exposing them to their fears incrementally. He worked on systematic desensitization with a methodology designed to treat people with extreme anxiety about specific events, situations, things, or people. His approach involved developing a hierarchy of anxiety-provoking situations, learning relaxation techniques, then associating these situations with relaxation, beginning at the bottom, or least anxiety-provoking, part of the hierarchy. He founded the Association for Advancement of Behaviour Therapy and the Journal of Behavior Therapy. |
| Robert Galambos | |
(source) |
Born 20
Apr 1914
American physiologist who, with Donald Griffin, confirmed that bats use echolocation to avoid obstacles while in flight. Their work conclusively proved Jurine's suggestion, of a century and a half before, that bats could hear sounds beyond the human range, and that this ability facilitated night flight. In their experiment (1938), a special microphone in a dark room was used to prove that bats flying in the dark could "see" by emitting ultrasonic vocal sounds and then navigating around obstacles using the echoes as an internal guidance system. Such flight was severely impaired if either a bat's ears were plugged, or its mouth was held closed by a loop of thread. Galambos' subsequent career was devoted to the neurophysiology of hearing and the brain.«  Listening
in the dark: The acoustic orientation of bats and men,
by Donald R Griffin. |
| Willi Hennig | |
| Born 20
Apr 1913; died 5 Nov 1976.
German zoologist recognized as the leading proponent of the cladistic school of phylogenetic systematics. According to this school of thought, taxonomic classifications should reflect exclusively, so far as possible, genealogical relationships. In effect, organisms would be grouped strictly on the basis of the historical sequences by which they descended from a common ancestor. This diverges significantly from evolutionary systematics, the traditional school of thought which holds that taxonomic classifications ought to be based on genetic as well as genealogical affinities. |
|
| Charles Gordon Curtis | |
(source) |
Born 20
Apr 1860; died 10 Mar 1953.
U.S. inventor who devised a steam turbine widely used in electric power plants and in marine propulsion. He was a patent lawyer for eight years. He patented the first U.S. gas turbine (1899). Among his other achievements, the Curtis multiple-stage steam turbine (patented 1896, sold rights to GE in 1901) required one tenth the space and weighed one eighth as much as machines it replaced. The Curtis generator was the most powerful steam turbine in the world and represented a significant advance in the capacity of steam turbines. In spite of its high-power output, this machine cost much less than contemporary reciprocating steam engine-driven generators of the same output. Image: One of Curtis's first steam turbines - 50kw. |
| Wilhelm Körner | |
(source) |
Born 20
Apr 1839; died 28 Mar 1925.
German organic chemist who established in 1874 how to determine the positions of the substituents on di- and tri-substituted isomers of the benzene ring by counting product or source isomers (five years before the van't Hoff-Le Bel hypothesis of tetrahedral carbon.) Because the 1,2-disubstituted isomer gives two products; the 1,3 gives three; and the 1,4 gives only one, both starting compounds and products can be identified. This identifies both starting materials and products. From 1864-67, Korner worked directly with August Kekulé (who realized the ring structure of benzene). The 126 aromatic compounds he prepared included pyridine (1869) and asparagine (1887, with Angelo Menozzi). He died by suicide.« 
[Image: diagram showing how each disubstituted isomer (top) produces a
different range of possible trisubstituted products (bottom) as listed
in the text above. ] |
| James David Forbes | |
(source) |
Born 20
Apr 1809; died 31 Dec 1868.
Scottish physicist noted for his research on heat conduction and glaciers. In 1836-44, he described the polarization (alignment of waves to vibrate in a plane) of radiant infrared heat by the mineral tourmaline, by transmission through a bundle of thin mica plates, and by reflection from the surfaces of a pile of mica plates. In 1846 he began experiments on the temperature of the Earth at different depths and in different soils near Edinburgh. Later he investigated the laws of heat conduction in bars, and in his last piece of work reported that iron conducts heat less efficiently as its temperature rises. He was among the first to study glacier movements and was involved with Tyndall in the great glacier controversy of the 1850s. |
| Sir William Edmond Logan | |
Age 58 (source) |
Born 20
Apr 1798; died 22 June 1875.
Canadian geologist, who was the "Father of Canadian Geology." With his uncle's coal and copper-smelting business in Wales, he made geologic maps of coalfields in Wales. His practice of geology arose from a desire to understand the sources of coal and ores. He noted the relationship between the underlying clay layers and fossil tree roots with local coal beds. This substantiated the theory that coal beds are formed in place. When he began as director (1842-69) of the new Geological Survey of Canada, its geology was virtually unknown. He produced the monumental Report on the Geology of Canada (1863) which recorded 20 years of research, fieldwork, plotting maps, preparing reports, and examining fossil and mineral specimens. |
| Marc Séguin, the Elder | |
(source) |
Born 20
Apr 1786; died 24 Feb 1875.
French engineer and inventor of the wire-cable suspension bridge and the tubular steam-engine boiler. Séguin (a nephew of Joseph Montgolfier, the pioneer balloonist) developed an early interest in machinery. By 1822, he was studying the strength of wire cables. With his brother Camille he studied the principles of the suspension bridge, at that time built with chain cables. In 1824, they built a bridge suspended from cables of parallel wire strands over the Rhône River at Tournon, the first such bridge, then copied around the world. Séguin also improved locomotive efficiency with his invention of the multiple fire-tube boiler, in place of the water-tube boiler used by the earlier steam engines. The brothers collaborated in the construction of the first French railroad (1824-33). |
| Philippe Pinel | |
(source) |
Born 20
Apr 1745; died 25 Oct 1826
French physician who pioneered in the humane treatment of the mentally ill. In 1792 he became the chief physician at the Paris asylum for men, Bicêtre, and made his first bold reform by unchaining patients, many of whom had been restrained for 30 to 40 years. He did the same for the female inmates of Salpêtrière when he became the director there in 1794. Discarding the long-popular equation of mental illness with demoniacal possession, Pinel regarded mental illness as the result of excessive exposure to social and psychological stresses and, in some measure, of heredity and physiological damage. |
| William Bartram | |
| Born 20
Apr 1739; died 22 Jul 1823.
American traveller and naturalist, the son of botanist John Bartram, whom he accompanied on botanical expeditions. From 1773, William Bartram made his own exploration of several Southern states, observing the wildlife: birds, animals, fishes as well as plants. He also made notes on life of the Indians. He wrote about his journeys in much the reprinted Travels (1791). Alexander Wilson, a Scottish immigrant to America, was inspired to become a leading ornithologist with Bartram's coaching. When Benjamin Smith Barton authored the first botanical textbook published in the U.S., Elements of Botany (1803), Bartram illustrated it. |
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| APRIL 20 - DEATHS | |
| Alfred Cort Haddon | |
(source) |
 Died
20 Apr 1940 (born 24 May 1855)
English anthropologist who is recognised as one the founders of modern British anthropology as an observational science. He began as a professor of zoology, and in 1888 spent eight months studying the coral reefs and marine zoology of the Torres Straits. He thereby became interested in the folk-lore, ceremonies and beliefs of the islanders and began to rescue such fast-perishing knowledge by collecting information from the elders. He organised the Cambridge Anthropological Expedition to the Torres Strait Islands in 1898, as he saw a need in the field of ethnology to make intensive studies in limited areas. Upon his return, he changed disciplines from biology to ethnology at the Cambridge University Museum.*« Magic
and Fetishism, by Alfred Cort Haddon. |
| Charles Sumner Tainter | |
(source) |
Died
20 Apr 1940 (born 25 Apr 1854)
American inventor of various sound-recording instruments, including the photophone (1880, with Alexander Graham Bell), an instrument for transmitting sound to a distance through the agency of light, using sensitive selenium cells. He also developed the Graphophone (1881, patented 1886; with Chichester A. Bell, a cousin of Alexander Graham Bell). This greatly improved on the tinfoil surface and rigid stylus then used by Thomas A. Edison. Tainter devising a wax-coated cardboard cylinder and a flexible recording stylus which incised the grooves (rather than embossing) to achieve better reproduction, making the phonograph and the dictagraph commercially possible. |
| William Henry Holmes | |
1884 (source) |
Died
20 Apr 1933 (born 1 Dec 1846)
American archaeologist, artist, and museum director who helped to establish professional archaeology in the United States. He was a geologist and outstanding illustrator who turned to archaeology while working for the U.S. Geological Survey (1875) and became an expert on southwestern Indian art and prehistoric ceramics and stone implements. His knowledge of geology, archaeology, anthropology, and ethnology made him a master in the scientific documentation of landscapes. His achievements included important publications on Indian cultures in prehistory and on Mayan civilization at Chichen Itza. He was chief of the Bureau of American Ethnology (1902-09) and director of the National Gallery of Art (1920-32). |
| Giuseppe Peano | |
(source) |
Died
20 Apr 1932 (born 27 Aug 1858)
Italian mathematician who founded symbolic logic. Through the use of symbols, equations are more easily understood by anyone regardless of their language. For example, Peano introduced symbols to represent "belongs to the set of" and "there exists." In Arithmetics principia (1889), a pamphlet he wrote in Latin, Peano published his first version of a system of mathematical logic, giving his Peano axioms defining the natural numbers in terms of sets. In 1903, Peano unsuccessfully proposed an international, artificial language he called "Latino sine flexione." It was based on Latin without grammar. Its vocabulary comprised words from English, French, German and Latin.«  |
| Ferdinand Braun | |
| Died
20 Apr 1918 (born 6 Jun 1850)
German physicist who shared the Nobel Prize for Physics in 1909 with Guglielmo Marconi for the development of wireless telegraphy. Braun is also known as the developer of the cathode-ray oscilloscope. He demonstrated the first oscilloscope (Braun tube) in 1897, after work on high-frequency alternating currents. Cathode-ray tubes had previously been characterized by uncontrolled rays; Braun succeeded in producing a narrow stream of electrons, guided by means of alternating voltage, that could trace patterns on a fluorescent screen. |
|
| Alfred Cort Haddon | |
| Died
20 Apr 1940 (born 24 May 1855)
One of the founders of modern British anthropology. Virtually the sole exponent of anthropology at Cambridge for 30 years, it was largely through his work and especially his teaching that the subject assumed its place among the observational sciences. |
|
| George Ferdinand Becker | |
| Died
20 Apr 1919 (born 5 Jan 1847)
American geologist who advanced the study of mining geology from physical, chemical, and mathematical approaches. Becker's main interest was the study of the Earth's interior, and his theoretical work on this topic was presented in a series of important papers in the 1890s; his most important theoretical contribution was Finite Homogeneous Strain, Flow, and Rupture of Rocks (1893). |
|
| Charles Friedel | |
(source) |
Died
20 Apr 1899 (born 12 Mar 1832)
French organic chemist and mineralogist who, with the American chemist James Mason Crafts, discovered in 1877 the chemical process known as the Friedel-Crafts reaction. In 1856, after studying in Strasburg, Friedel was appointed conservator of the mineralogical collections at the Superior National School of Mines. In 1871 he began to lecture at the École Normale and in 1876 became professor of mineralogy at the Sorbonne, but on the death of Wurtz in 1884 he exchanged that position for the chair of organic chemistry. He collaborated in efforts to form diamonds artificially, studied the pyroelectric properties of crystals, determined crystallographic constants, and did research on ketone and aldehyde compounds. |
| Chauncey Jerome | |
(source) |
Died
20 Apr 1868 (born 10 Jun 1793)
American inventor and clockmaker whose products enjoyed widespread popularity in the mid-19th century. About 1838 Jerome invented the one-day brass movement, an improvement over the wood clock. Applying the mass-production techniques of American inventor Eli Whitney, Jerome flooded the United States with low-priced brass clocks. His clocks quickly spread to Europe and so astonished the English that "Yankee ingenuity" became a byword. In the 1850s Jerome became associated with unethical businessmen, and his company failed; he died in poverty. |
| Ignatz Venetz | |
(source) |
Died
20 Apr 1859 (born 21 Mar 1788)
Swiss geologist who was one of the first to propose that vast glaciers once covered a substantial portion of the earth's surface. He came to this conclusion by observing that typical striations left in rock by glaciers extended for many miles beyond the limits of existing glaciers. He published these thoughts in 1821, but they were generally ignored. Jean de Chapentier supported Venetz in these ideas, but was also ignored. However, they influenced Louis Agassiz who developed them. |
| Robert Livingston Stevens | |
(source) |
Died
20 Apr 1856 (born 18 Oct 1787)
U.S. engineer and ship designer who invented the widely used inverted-T railroad rail (1830) and the railroad spike. He found that rails laid on wooden ties, with crushed stone or gravel beneath, provided a roadbed superior to any known before. His rail and roadbed came into universal use in the United States. He also added the pilot, or cowcatcher, to the locomotive and increased the number of drive wheels to eight for better traction. He tested the first steamboat to use screw propellers, invented and built by his father, John Stevens. |
| Franz Karl Achard | |
(source) |
Died
20 Apr 1821 (born 28 Apr 1753)
German chemist who invented a process for the large-scale extraction of table sugar (sucrose) from beets, and in 1801, opened the first sugar-beet factory, in Silesia (now Poland). At first, though simple, the method was costly, He improved it using suggestions of the Institute in France, including that the beets be pressed without cooking them, which saved much expense for fuel. He had succeeded Andreas Sigismund Marggraf upon his death (1782) as director of the "Class of Physics" at the Berlin Academy. It was Marggraf that had first discovered the presence of sugar in beetroot, and isolated it on an experimental scale in 1747. Achard also discovered a method for working platinum and was the first to prepare a platinum crucible (1784). |
| Jean-Baptiste-Gaspard Bochart de Saron | |
| Died
20 Apr 1794 (born 16 Jan 1730)
French lawyer and natural scientist who became especially known for his advances in astronomy. He was a patron of the sciences, financing the publication of the marquis de Laplace's Theory of the Movement and Elliptic Figure of the Planets (1784) and developing one of Europe's largest and finest collections of reflecting telescopes and other astronomical instruments for his own use and the use of his scientific friends. Bochart's own studies included calculation of the orbits of comets, using data contributed by his long-time collaborator Charles Messier. His political activities led to his death by guillotine during the French Revolution. |
|
| John Goodricke | |
(source) |
Died
20 Apr 1786 (born 17 Sep 1764)
English astronomer who was the first to notice that some variable stars were periodic. Born a deaf-mute, after a proper education he was able to read lips and to speak. He was the first to calculate the period of Algol to 68 hours and 50 minutes, where the star was changing its brightness by more than a magnitude as seen from Earth. He was also first to correctly propose that the distant sun is periodically occulted by a dark body. John Goodricke was admitted to the Royal Society on 16 April 1786, when 21 years old. He didn't recognized this honour, because he died four days later, in York, by pneumonia. |
| Johann Christoph Denner | |
(source) |
Died
20 Apr 1707 (born 13 Aug 1655)
German inventor, maker of musical instruments and inventor of the clarinet. He made improvements to the chalumeau, the first true single reed instrument, of the late 1600's. He and his son Jacob are attributed with innovating the speaker key which gave the clarinet a larger register. The clarinet overblows at the 12th. That is, when playing a C without the speaker key, then add the speaker key, the note that sounds is a G, which is the interval of a twelfth. The other woodwind instruments overblow at the octave. The clarinet bore is cylindrical, whereas every other woodwind instrument has a conical bore (even the flute!). This is why the clarinet overblows at the twelfth and is so laden with overtones, which contributes to its unique sound. |
| APRIL 20 - EVENTS | |
| Apollo 16 | |
In 1972, Apollo 16 astronauts landed on the moon for a return trip. |
|
| Picturephone | |
(source) |
In 1964, the first picturephone
transcontinental call was made between New York City and Anaheim, California.
The
device
consisted of a telephone handset and a small, matching TV. It allowed telephone
users to see each other in fuzzy video images as they carried on a conversation.When
Picturephone debuted in 1964, at the World's Fair, prices ranged from $16
to $27 for a three-minute call between special booths AT&T set up in
New York, Washington and Chicago. It never became popular after it was
briefly offered commercially in Chicago. If |
| Electron microscope | |
|
In 1940, the first U.S. electron misroscope was demonstrated in Philadelphia,
Pennsylvania. It was able to produce a magnification of 100,000 times,
in an apparatus 10 feet high and weighing half a ton. The inventor was
Dr. Vladimir Zworykin at the RCA laboratories, Camden, New Jersey. |
|
| Radium | |
 |
In 1902, Marie and Pierre Curie isolated one gram of radium, the first
sample of the radioactive element. They had refined it from eight tons
of pitchblende ore. |
| Simon Lake submarine patent | |
(USPTO) |
In 1897, a U.S. patent was issused for a "Submarine Vessel" invented by
Simon
Lake (No. 581,213). It described oscillatory lateral vanes on the sides
of the vessel to set for ascending or descending, a weight to shift fore-and-aft
to keep the vessel on an even keel, a compressed air reservoir, ballast
tanks, an "air-tight diver's chamber provided at the bottom with a trap"
(suitable for diving salvage operations), and wheels to travel on the water-bed
which could be propelled and steered from within. Lake was interested in
the use of a submarine for commercial, rather than military, purposes.
It had a hinged observation tube, which could be provided with a mirror
(forerunner of the perioscope). It was expected to be steam-powered on
the surface (but in practice the heat generated by the boiler was intolerable
to a crew, and thus impracticable.)«
[Image:
rear view of submarine, showing hull with lateral vanes, wheels and propeller.] |
| American Chemical Society | |
|
In 1876, the first national chemical society in the U.S., the American
Chemical Society, was organized in New York City. |
|
| Pasteurization | |
 |
In 1862, the first test of pasteurization
was completed by Louis
Pasteur and Claude Bernard. Jars, sealed since 3 Mar, were opened at
a meeting of the French Academy of Sciences. They containing dog's blood
and urine that had been maintained at an elevated temperature of 30ºC.
Neither liquid showed observable decay or fermentation. This suggested
the possibility of heating foods sufficiently to kill germs without significantly
altering their chemical composition. Pasteurization was applied by brewers.
By heating the finished beer to above 160ºF, to kill harmful bacteria,
a germ-free beer could be produced which did not require constant refrigeration
for lengthy shipment or storage. It also came to be used for milk and other
products. |
| Carpet power loom | |
(source) |
In 1837, the first U.S. patent was issued for a carpet power loom, to Erastus
B. Bigelow of West Boyston, Mass. |
| Hot Springs National Park | |
(source) |
In 1832, what is now Hot Springs National Park in Arkansas was established
as a reservation by an act of Congress. Its 911 acres encompassed 46 hot
springs. It was not designated as a National Park until 4 Mar 1921. Yellowstone
National Park was the first to be declared a U.S. National Park (authorized
on 1 Mar 1872). Thus, Hot Springs is the nation's oldest national park,
though not the first to carry the "National Park" designation. The park
is wrapped around the core of the city of Hot Springs retaining much of
the experience of early-1900s health-seekers who came to take thermal baths
in the city's bathhouses and hotels. American Indian tribes had used the
thermal springs for centuries before the territory was settled by whites. |
