| APRIL 25 - BIRTHS | |
| Gerard Henri de Vaucouleurs | |
(source) |
 Born 25
Apr 1918; died 7 Oct 1995.
French-born U.S. astronomer whose pioneering studies of distant galaxies contributed to knowledge of the age and large-scale structure of the universe. He produced three Reference Catalogues of bright galaxies (1964, 1976, 1991). Each was a homogenization of data from widely different sources, so that the catalogues would not be merely finding lists or data collection lists, but astrophysically useful databases. Using data in the Reference Catalogues, he was able to develop new distance indicators and refine others. His unique philosophy on distance matters was "spreading the risks," that is, applying as many different and independent techniques as possible to check for scale and zero-point errors. |
| Meyer Fortes | |
(source) |
Born 25
Apr 1906; died 27 Jan 1983.
English social anthropologist (born in South Africa) known for his investigations of West African societies. He turned in 1932 to anthropology after originally training in psychology, which shows in his later works on ancestor worship. He was primarily interested in family and kinship, and made field studies (1934–37) with the Tallensi and Ashanti in Ghana. His monographs on these studies laid the foundations for the theory of descent, a cornerstone of the "structural-functionalism" dominating the social anthropology of the 1950s and 60s. His major contributions in lineage theory, studies of religion and ancestor worship set the standard for all subsequent studies of African social organization. He was professor of social anthropology at Cambridge University (1950-73).«  The
web of kinship among the Tallensi, by Meyer Fortes. |
| Andrey Nikolayevich Kolmogorov | |
(source) |
Born 25
Apr 1903; died 20 Oct 1987.
Russian mathematician whose basic postulates for probability theory that have continued to be an integral part of analysis. This work had diverse applications such as his study of the motion of planets (1954), or the turbulent air flow from a jet engine (1941). In topology, he investigated cohomology groups. He made a major contribution to answering the probability part of Hilbert's Sixth Problem, and completely resolved (1957) Hilbert's Thirteenth Problem. Kolmogorov was active in a project to provide special education for gifted children, not only by writing textbooks and in teaching them, but in expanding their interests to be not necessarily in mathematics, but with literature, music, and healthy activity such as on hikes and expeditions.« |
| Wolfgang Pauli | |
(source) |
Born 25
Apr 1900; died 15 Dec 1958
Austrian-born American winner of the Nobel Prize for Physics in 1945 for his discovery in 1925 of the Pauli exclusion principle, which states that in an atom no two electrons can occupy the same quantum state simultaneously. This principle clearly relates the quantum theory to the observed properties of atoms. No
Time to be Brief: A Scientific Biography of Wolfgang Pauli,
by Charles P. Enz. |
| John Chipman | |
| Born 25
Apr 1897; died 14 May 1983
American physical chemist and metallurgist who was instrumental in applying the principles of physical chemistry to constituents in liquid metals and to the chemical reactions between slag and liquid iron that are important in the production of pig iron and steel. |
|
| Pavel Sergeevich Aleksandrov | |
| Born 25
Apr 1896; died 16 Nov 1982.
Soviet mathematician who made important contributions to the field of topology, the study of related physical or abstract elements that remain unchanged under certain distortions. |
|
| Guglielmo Marconi | |
(source) |
Born 25
Apr 1874; died 20 July 1937.
Italian inventor, born in Bologna. He was a physicist, who invented the wireless telegraph in 1935 known today as radio. Nobel laureate (1909). In 1894, Marconi began experimenting on the "Hertzian Waves" (the radio waves Hertz first produced in his laboratory a few years earlier). Lacking support from the Italian Ministry of Posts and Telegraphs, Marconi turned to the British Post Office. Encouraging demonstrations in London and on Salisbury Plain followed. Marconi obtained the world's first patent for a system of wireless telegraphy, in 1897, and opened the world's first radio factory at Chelmsford, England in 1898. In 1900 he took out his famous patent No. 7777 for "tuned or syntonic telegraphy." |
| Félix d' Hérelle | |
(source) |
Born 25
Apr 1873; died 22 Feb 1949.
French-Canadian microbiologist generally known as the discoverer of the bacteriophage, a virus that infects bacteria. (The earlier identification of the bacteriophage by the British microbiologist F.W. Twort in about 1915 became obscured by Twort's disinclination to take credit for or to pursue his initial findings. |
| Charles Sumner Tainter | |
(source) |
Born 25
Apr 1854; died 20 Apr 1940
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. |
| John Frank Stevens | |
| Born 25
Apr 1853; died 2 June 1943.
American civil engineer and railroad executive who, as chief engineer of the Panama Canal from late 1905 to April 1907, laid the basis for that project's successful completion. |
|
| Felix Klein | |
(source) |
Born 25 Apr 1849; died 22 June 1925.
German mathematician whose synthesis of geometry as the study of the properties of a space that are invariant under a given group of transformations, known as the Erlanger Programm, profoundly influenced mathematical development. He created the Klein bottle, a one-sided closed surface. A Klein bottle cannot be constructed in Euclidean space. It is best pictured as a cylinder looped back through itself to join with its other end. However this is not a continuous surface in 3-space as the surface cannot go through itself without a discontinuity. It is possible to construct a Klein bottle in non-Euclidean space. |
| François Hennébique | |
(source) |
Born 25
Apr 1842; died 20 Mar 1921.
French engineer who was an important leader in experimenting with various ways of reinforcing concrete with iron and steel. At the Paris Exposition of 1867, Hennebique saw Joseph Monier's tubs and tanks built of concrete reinforced with wire mesh, and began experimenting with ways to apply this new material to building construction, setting up his own firm (1867). First using reinforced-concrete floor slabs (1879), he progressed to a complete building system, patented 1892, using his invention of a method using hooked connections on reinforcing bars. Hennébique introduced his techniques into Britain when he was commissioned to build a new flour mill in Swansea (completed 1898). This was the first multistorey reinforced concrete building in Britain. |
| Sir Marc Isambard Brunel | |
(source) |
Born 25
Apr 1769; died 12 Dec 1849.
French-born English engineer and inventor who solved the historic problem of underwater tunneling. A prolific inventor, Brunel designed machines for sawing and bending timber, boot making, stocking knitting, and printing. As a civil engineer, his designs included the Île de Bourbon suspension bridge and the first floating landing piers at Liverpool. In 1818, however, Brunel patented the tunneling shield, a device that made possible tunneling safely through waterbearing strata. On 2 Mar 1825 operations began for building a tunnel under the Thames River between Rotherhithe and Wapping. The Thames Tunnel was eventually opened on 25 Mar 1843. It has a twin horseshoe cross-section with height of 23-ft (7m), width of 37-ft (11m), and total length 1,506-ft (406m). |
|
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| APRIL 25 - DEATHS | |
| Francis P. Shepard | |
 Died
25 Apr 1985 (born 10 May 1897)
Francis P(arker) Shepard was an American marine geologist whose pioneering surveys of submarine canyons off the coast of California near La Jolla marked the beginning of Pacific marine geology. |
|
| Charles Mauguin | |
(source) |
Died
25 Apr 1958 (born 19 Sep 1878)
Charles-Victor Mauguin was a French mineralogist and crystallographer who was one of the first to make a systematic study of the silicate minerals. Using X-ray diffraction techniques, he determined the structure of a large number of micas. He also published the atomic structure of cinnabar, calomel and graphite and devised a system of symbols for designation of symmetry properties of crystals, adopted (1935) as international standard.« |
| Wilhelm Dörpfeld | |
(source) |
Died
25 Apr 1940 (born 26 Dec 1853)
German archaeologist who was the first to study the construction of ancient Greek theatres. He worked with Ernst Curtius as a member of the excavation team at the Olympia site in Greece (1877-81), where Dörpfeld developed the method of dating ancient archaeological sites based on the strata in which objects were found and the type of building materials. He excavated the Mycenaean palace at Tiryns, Greece (1884-85). He was an associate of the German archaeologist Heinrich Schliemann assisting in the search for the Harbour of Troy, at Hisarlik, Turkey (1882-83). Dörpfeld continued that work (1893-94) after Schliemann's death.« |
| Floyd Bennett | |
(source) |
Died
25 Apr 1928 (born 25 Oct 1890)
American pioneer aviator who piloted the explorer Richard E. Byrd on the first successful flight over the North Pole on 9 May 1926, in a three-engine Fokker monoplane, Josephine Ford. They flew 1,360 miles from King's Bay, Spitzbergen, to the Pole and back in 15-1/2 hours. During his aviation duty in the Navy Bennett had met Byrd (1925) as his commander on the Donald B. MacMillan expedition to northwestern Greenland. Byrd realized that Bennett was more than a good pilot, he was fearless, and one of the finest practical men in the Navy for handling an airplane's temperamental mechanisms. Together, they planned the North Pole flight. For his share in the achievement Bennett received the Congressional Medal of Honor. |
| Henri Duveyrier | |
| Died
25 Apr 1892 (born 28 Feb 1840)
French explorer of the Sahara whose observations of the Tuareg people contributed to African ethnology. His explorations took him from Morocco to Tunisia through the region south of the Atlas Mountains. Duveyrier devoted special attention to the customs and speech of the Tuareg--pastoralists and brigands with a penchant for poetry--among whom he lived for months at a time. |
|
| William Beaumont | |
(source) |
Died
25 Apr 1853 (born 21 Nov 1785)
US army surgeon, the first person to observe and study human digestion as it occurs in the stomach. As a young army surgeon stationed on Mackinac Island in Michigan, Beaumont was asked to treat a shotgun wound. The woundwas "more than the size of the palm of a man's hand," Beaumont wrote. The patient, Alexis St. Martin, survived but was left with a permanent opening into his stomach from the outside. Over the next few years, Dr. Beaumont used this crude fistula to sample gastric secretions. He identified hydrochloric acid as the principal agent in gastric juice and recognized its digestive and bacteriostatic functions. Moreover, many of his conclusions about the regulation of secretion and motility remain valid to this day. |
| Siméon-Denis Poisson | |
(source) |
Died
25 Apr 1840 (born 21 Jun 1781)
French mathematician known for his work on definite integrals, advances in Fourier series, electromagnetic theory, and probability. The Poisson distribution (1837) describes the probability that a random event will occur in a time or space interval under the conditions that the probability of the event occurring is very small, but the number of trials is very large so that the event actually occurs a few times. His works included applications to electricity and magnetism, and astronomy. He is also known for the Poisson's integral, Poisson's equation in potential theory, Poisson brackets in differential equations, Poisson's ratio in elasticity, and Poisson's constant in electricity. |
| Anders Celsius | |
(source) |
Died
25 Apr 1744 (born 27 Nov 1701)
Swedish astronomer, physicist and mathematician who is famous for the temperature scale he developed. Celsius was born in Uppsala where he succeeded his father as professor of astronomy in 1730. It was there also that he built Sweden's first observatory in 1741. He and his assistant Olof Hiortner discovered that aurora borealis influence compass needles. Celsius' fixed scale (often called centigrade scale) for measuring temperature defines zero degrees as the temperature at which water freezes, and 100 degrees as the temperature at which water boils. This scale, an inverted form of Celsius' original design, was adopted as the standard and is still used in almost all scientific work. |
| Leon Battista Alberti | |
(source) |
Died
25 Apr 1472 (born 18 Feb 1404)
Artist and geometrist. As an artist, he "wrote the book," the first general treatise Della Pictura (1434) on the the laws of perspective, establishing the scienceof projective geometry. Alberti also worked on maps (again involving his skill at geometrical mappings) and he collaborated with Toscanelli who supplied Columbus with the maps for his first voyage. He also wrote the first book on cryptography which contains the first example of a frequency table. |
| APRIL 25 - EVENTS | |
| Hubble Space Telescope | |
(NASA) |
In 1990, the $2.5 billion Hubble Space Telescope was deployed
in space from the Space Shuttle Discovery into an orbit 381 miles
above Earth. It was the first major orbiting observatory, named in honour
of American astronomer, Edwin Powell
Hubble. It was seven years behind schedule and nearly $2 billion over
budget. In orbit, the 94.5-in primary mirror was found to be flawed, giving
blurred images and reduced ability to see distant stars. However, correcting
optics were successfully installed
in 25 Dec 1993. The telescope 43-ft x 14-ft telescope now provides images
with a clarity otherwise impossible due to the effect of the earth's atmosphere.
Instrument packages capture across the electromagnetic spectrum. |
| Pioneer 10 | |
|
In 1983, Pioneer 10 crossed the orbit of Pluto, the outermost planet,
to continue its voyage into the universe beyond our solar system |
|
| First AIDS patient | |
|
In 1959, a 25-year-old patient, an apprentice printer, entered the Royal
Manchester Infirmary in England, where he died 4-1/2 months later for reasons
that were then unknown. His preserved tissue samples were examined in 1990.
In a letter to the journal The Lancet, Gerald Corbitt - director
of clinical virology at the hospital - suggested this could be the earliest
known AIDS case. In 1995, the journal Nature, reported
that the results were anomolous:
the putative HIV detected was of a "relatively modern strain." Although
having doubts since 1992, Corbitt said he regarded the analysis as no more
than a trial of PCR [polymerase chain reaction] on archival material."
Belatedly, the report of a possible early AIDS case was clarified. |
|
| Atomic reactor | |
|
In 1957, an experimental sodium reactor (SRE) began operation producing
about 6,000 kilowatts of electricity. It was located about 30 miles northwest
of Los Angeles, in the Santa Susana Mountains, California. It was
built for the Atomic Energy Commission by Atomics International, a division
of North American Aviation., Inc. |
|
| DNA structure | |
(source) |
In 1953, the Nature journal publishedthe
structure of DNA, as suggested in a one-page article by James Watson and
Francis Crick. Their work earned the pair of scientists a Nobel Prize in
1962. The structure explained how DNA passed heriditary information from
cell to cell, and from generation to generation. "This structure has two
helical chains each coiled around the same axis... Both chains follow right-handed
helices... The novel feature of the structure is the manner in which the
two chains are held together by purine and pyrimidine bases... They are
joined together in pairs, a single base from one chain being hydrogen-bonded
to a single base from the other chain, so that the two lie side by side
with identical z-co-ordinates."« [Image:
DNA as illustrated in the Nature article.] |
| Manhattan project | |
|
In 1945, the new U.S. President, Harry S. Truman was briefed on the status
of the atomic bomb project. Within 24 hours of Roosevelt's death on 12
Apr 1945, Truman had been told briefly about the atomic bomb project by
Secretary of War Henry Stimson. In this more extensive briefing on 25 Apr,
Stimson, with General Groves's assistance, gave Truman information that
the uranium-235 gun design had been frozen, but sufficient uranium-235
would not be accumulated until around 1 Aug. Enough plutonium-239 would
be available for an implosion assembly to be tested in early July; a second
would be ready in August. eb |
|
| Forestry congress | |
|
In 1882, the first national U.S. forestry society, held the American Forestry
Congress in Cincinnati, Ohio. |
|
| Oil well torpedo | |
 |
In 1865, a U.S. patent was issued, the first for a "torpedo" used in oil
well drilling (No. 47,458). The inventor was Col. Edward A.L. Roberts of
New York City, who had successfully experimented with it in Jan 1865 to
open an obstructed well bore at the Ladies' Well on Watson Flats, near
Titusville, Pennsylvania. |
| Suez Canal | |
|
In 1859, ground was broken for the Suez Canal. The first blow of the pickax
was given by Ferdinand vicomte de Lesseps at Port Said. |
|
| U.S. Patent for Carriage Propulsion | |
In 1794, U.S. letters
patent were granted by George Washington to John J. Staples, Jr., of
New York, for what the inventor described as a "Carriage to be Propelled
by the Mechanic Powers" (not steam power). However, reading the text of
the patent shows that the specifications were vague, and the invention
wholly impractical. It proposed five powers be used, including "The first
power ... is the weight of the whole carriage ... which is raised up by
the oval wheels in turning round, and when descending acts on the shortest
lever. 2d Power is the weight of the top frame which supports the carriage
body ... which being likewise wound up by the said oval wheels at the same
or a different time acts in descending on the two next size levers."  |
|
| Guillotine | |
|
In 1792, in Paris, the guillotine was first used on a human, highwayman
Nicolas Jacques Pelletier, after having been tested during its development
with corpses and sheep. The guillotine was invented in 1788 by French surgeon
Antoine Lewis, and named for the French politician Joseph Ignace Guillotin
who promoted its use as more humane method of execution. |
|
