Joseph LeConte

Joseph LeConte was born on February 26, 1823 on the plantation "Woodmanston" in Liberty County, Georgia. He was the fifth child and youngest son in the family. His mother died of pneumonia when he was three. His father, who had trained as a doctor, but did not earn a degree, ran the family plantation and set up a chemical laboratory in his house and a botany garden for the education of his sons. As a boy LeConte frequently ranged the backwoods of Liberty County with his older brothers and took an interest in nature. He attended a country school set up by several of the plantation families and among his teachers was Alexander Hamilton Stephens, who was later a U.S. Senator and vice-president of the Confederacy, and with whom he maintained a lifelong friendship.

He attended Franklin College which later founded the University of Georgia in Athens, Georgia. He graduated in 1841. After graduation he began studying medicine under Charles West in Macon, Georgia and then he attended the New York College of Physicians and Surgeons, graduating with a medical degree in 1845. He practiced medicine for three years in Macon, Georgia and then studied history at Harvard University, in Boston, Massachusetts, studying under Louis Agassiz. After graduation in 1851, he accompanied an expedition lead by Agassiz to the Florida Reef. After the expedition he became a professor of natural science at Oglethorpe College in Midway, Georgia. From 1852 to 1856 he was a professor of natural sciences and geology at Franklin College and from 1857 to 1869 he was a professor of chemistry and geology at South Carolina College (later the University of South Carolina) in Columbia, South Carolina. During the American Civil War he continued teaching, but also ran a niter works used to produce explosives. In 1869 he moved to California, taking a job as the first professor of natural history and geology at the newly founded University of California, at Berkeley. He remained there until his death.

LeConte was primarily a geologist but he also wrote papers on monocular and binocular vision. He was also an early proponent of Charles Darwin's theory of natural selection. LeConte was one of the early supporters of the theory of contraction formation of mountain ranges. The theory was that when the earth was formed it was a molten ball  and as it cooled ridges on the surface developed. These ridges are the mountain ranges we see today. This theory of mountain range formation has been replaced by plate tectonic theory. LeConte was also an ardent conservationist. He was friends with John Muir, and with Muir was a co-founder of the Sierra Club. In 1874 he was nominated to the National Academy of Science. He served as president of the American Association for the Advancement of Science in 1892 and president of the Geological Society of America in 1896.

He died on July 6, 1901 of a heart attack, while in Yosemite Valley. He was to be leaving on a Sierra Club trip the next day.


References:

LeConte, Joseph; "The Autobiography of Joseph LeConte", edited by William Dallam Ames; D. Appleton and Company; 1903

Hilgard, Eugene W.; "Biographical Memoir of Joseph LeConte: 1823-1901"; in Biographical Memoirs; National Academy Press; 1907

Joseph LeConte Wikipedia Entry

Svante August Arrhenius

Svante August Arrhenius was born on February 19, 1859 in Vik, a village near Uppsala, Sweden. His father, Svante Gustaf Arrhenius, was a land surveyor who worked for the University of Uppsala. The family moved to Uppsala in 1860. A gifted child, Arrhenius learned to read from lessons given by his older brother Janne. He learned to do arithmetic by watching his father keeping the accounts that he was responsible for. At age 8 he entered the local cathedral school, starting in 5th grade. He excelled at mathematics and physics, graduating as the youngest and most able student in 1876. In the autumn of 1876 Arrhenius entered the University of Uppsala, where he studied mathematics, physics and chemistry. He finished his bachelors in January 1878, finishing in a year and a half, a record at the time.

After a trip to Paris, he began his graduate studies in physics at the University of Uppsala, but due to the poor instruction he moved to Stockholm, studying under Erik Edland at the Physical Institute of the Swedish Academy of Sciences. Arrhenius began working for Edland studying electrical spark discharges, but moved on to studying the dissolution of electrolytes in water. Electrolytes are chemicals that when added to water make a solution that conducts electricity. Arrhenius discovered that electrolytes, when dissolved in water, break up into negatively and positively charged particles called ions. His thesis was not well received by his professors and was given the lowest possible passing grade.  Only after his defense was it raised to a third class rating.

 Arrhenius sent his thesis to two of the leading physical chemists of the time, Jacobus van't Hoff and Wilhelm Ostwald. Ostwald was so impressed that after some correspondence he traveled to Uppsala to offer Arrhenius a docent position in Riga, which at that time was part of the Russian Empire. Arrhenius decided to stay in Sweden and he was given an unpaid docent position at the University of Uppsala, the first such position in the emerging science of physical chemistry. In 1885, with the recommendation of Edland he received a traveling fellowship from the Swedish Academy of Science that allowed him to travel through Europe and work with prominent physical chemists. In 1886 he traveled to Riga to work with Ostwald and to Wurzburg to work with Friedrich Kohlrausch. In 1887 he traveled to Graz to work with Ludwig Boltzmann and in 1888 he traveled to Amsterdam to work with van't Hoff. During these trips he studied the effects of ions in solution, including the increase in the boiling point and lower the freezing point of ionic solutions versus pure solvents and the effects of ions in digestion and in the interaction of toxins and anti-toxins.

It was not until 1891, after he refused the offer of a professorship in Giessen, Germany, that he was made lecturer at Stockholm University College and in 1895 he was appointed professor of physics. In 1886 after studying the causes of ice ages he published a paper linking atmospheric carbon dioxide levels and rising temperatures. He calculated that if the level of carbon dioxide in the atmosphere doubled the temperature would rise by 5^o-6^oC. Scientists today say that it is really only a 2^o-3^oC rise in temperature. This rise in temperature is caused by the infrared absorption of carbon dioxide. The sun's rays warm the earth and it cools by releasing infrared radiation. This radiation is absorbed by carbon dioxide in the atmosphere and reflected back to earth, preventing it from escaping back into space. This is called the greenhouse effect, where carbon dioxide in the atmosphere keeps the earth warm by preventing heat from escaping. The cumulative effect of carbon dioxide and other greenhouse gasses give rise to global warming.

Around 1900 Arrhenius became involved with the Nobel Prize. In 1897, with the death of Alfred Nobel, the Swedish scientific establishment was left with the task of organizing the bequest from his will, prizes awarded to outstanding achievements in chemistry, medicine, physics, economics, literature, and peace that benefit mankind. Arrhenius was largely responsible for setting up the rules that govern the prizes. In 1903 he won the Nobel Prize for Chemistry for his work on the "electrolyte theory of dissociation". This was partly work he had done on his doctoral dissertation that only earned third class honors. Other honors he won include election as a foreign member to the Royal Society of England in 1911, the Society's Davy Medal and the Faraday Medal given by the Chemical Society, as well as many honorary doctorates.

Arrenius spent his later years writing  scientific textbooks and science books for a lay audience and he died on October 2, 1927 in Stockholm. He was buried in Uppsala.


References:

Arrhenius, Gustav; Caldwell, Karen; and Wold, Svante; "A tribute to the memory of Svante Arrhenius (1859-1927)"; The Royal Swedish Academy of Engineers (2008)

Sample, Ian; "The Father of Climate Change"; The Guardian; June 30, 2005

Svante Arrhenius Wikipedia Entry

Svante Arrhenius Nobel Biography

Marcel Gilles Jozef Minnaert

Marcel Gilles Jozef Minnaert was born on February 12, 1893 in Burges, Belgium. His father and mother were school teachers, liberal and supportive of Flemish causes. Minnaert, in his youth was influenced by his uncle, Gerard Minnaert, who was important in the Flemish movement. He grew up in a part of Belgium where Dutch was the common language but all the schools taught in French. After his father's death in 1902 his mother moved the family to Gent, Belgium. Minnaert went to secondary school in Gent and then to the University of Gent, where he studied natural sciences, particularly biology. While a student he was part of a movement to change the language of the university from French to Dutch. He earned his doctorate in biology in 1914.

In 1915-16 he spent a year in Leiden in order to study mathematics and physics. During the German occupation of Belgium he taught physics at the University of Gent, but was forced to flee in 1918, when the Germans left, because he was seen as a collaborator. He relocated to the University of Utrehct, in the Netherlands, where he worked for W.H. Julius who stimulated his interest in solar physics. He finished his second doctorate, this time in astronomy in 1925 the same year that Julius died. Minnaert replaced Julius as the director of the solar spectrograph research project at Utrecht. This was a fascinating time in stellar physics when atomic physics could finally explain what was really happening. Stars, like our sun, are fusing nucleons together, creating new atoms, making the matter that we are made of.

In 1928 he led a successful solar eclipse expedition. In 1940 he published the Utrecht Atlas of the Solar Spectrum and in 1941 he developed the Minnaert function, which is used in the observation of celestial bodies. In 1942, Minnaert, who never hid his liberal political views was taken prisoner by the Germans. He taught physics to his fellow prisoners while he was imprisoned. He was released in 1944. After the war, he returned to the University of Utrecht's observatory and remained director until his retirement in 1963. In addition to his astronomical writings Minnaert also published a physics book that was popular in the Netherlands and was translated, and also a book of poetry dealing with astronomical subjects. Honors won by Minneart include the Bruce medal, presented by the Astronomical Society of the Pacific in 1951 and a gold medal from the Royal Society of London, in 1947. Minneart also has a crater on the moon and an asteroid named after him.

Mineart died on October 26, 1970.


References:

De Jager, C.; "In Memoriam: Marcel Gilles Jozef Minnaert (12 Februarty 1893-26 October 1970)"; Astrophysics and Space Science(1971)10:83-85

Unsold, Albrecht;"In Memorian: Marcel Gilles Jozef Minnaert";Solar Physics(1971)17:3-5

Anon; "Biographies: Marcel Gilles Jozef Minnaert"; online at www.dwc.knaw.nl

Marcel Minnaert Wikipedia Entry

Sir Alan Lloyd Hodgkin

Sir Alan Lloyd Hodgkin was born on February 5, 1914 in Banbury, Oxfordshire, England. His family were Quakers and his pacifist father, George, died of dysentery in Baghdad while on a relief expedition to help Armenia refugees in 1918, when Hodgkin was 4. Hodgkin was raised by his mother. As a young boy he took an interest in natural history, wandering in the Oxford countryside. He attended the Downs School and Gresham's School, winning a scholarship to Trinity College, Cambridge, where he studied zoology, chemistry and mathematics. He graduated from Trinity in 1936. After graduation he did fellowships at Trinity and the Rockefeller Institute in New York.

Returning to Cambridge in 1939, he began working with his students Andrew Huxley and Richard Keynes studying nerve cell activation, but with the outbreak of World War II the research was temporarily abandoned. Hodgkin briefly worked in aviation medicine in Farbourough, England, but then transferred to the Telecommunications Research Establishment where he worked on radars for fighter planes. After the war he returned to Cambridge where he lectured in physiology and was appointed assistant director of research. He  continued researching nerve cells and Huxley and Keynes returned to work with him. They also worked part time at the Laboratory of the Marine Biological Institute in Plymouth where they used giant squid nerves for their research..

The research that they were doing involved the changes in nerve cell membrane ion permeability before, during, and after nerve excitation. Using nerve cells from giant squid they established that during nerve excitement, ion channels in the membrane open allowing sodium ions to flow through the cell membrane into the cell and potassium to flow out.  This flow of ions moves down the length of the nerve cell, conducting an electrical signal. This is the way excitable cells like muscle and heart cells, as well as nerve cells, activate. Later research showed that there were protein ion channels in the cell membrane that allow ions to flow across the membrane. For their work in describing nerve cell action potentials Hodgkin and Huxley, as well as Sir John Eccles, shared the 1963 Nobel Prize for physiology and medicine.

Other honors won by Hodgkin include, election to the Royal Society in 1948, the Foulerton Research Professorship in 1951, and the Copley Medal from the Royal Society in 1965. He served as the president of the Royal Society from 1970 to 1975, as chancellor of Leicester University from 1971 to 1984 and master of Trinity College from 1978 to 1984. He was knighted in 1972 and appointed to the Order of Merit in 1973.

Hodgkin died on December 20, 1998.


References:

Hodgkin, Sir Alan L.; "Sir Alan L. Hodgkin"; in The History of Neuroscience in Autobiography, Volume 1; The Society for Neuroscience; 1996

Anonymous; "Nobel Prize Winning Biologist Dies, Aged 84"; BBC News; December 20, 1998

Alan L. Hodgkin Nobel Biography

Alan Lloyd Hodgkin Wikipedia Entry