Sunday, December 25, 2011
After completing his postdoc he returned to Technishche Universtat Darmstadt as a pirvatdozant (lecturer). In 1935 Herzberg was forced to flee Germany because of his Jewish wife, and he took a position as a guest lecturer at the University of Saskatchewan in Saskatoon, Saskatchewan, which was almost immediately made permanent. Herzberg remained at the University of Saskatchewan until 1945 when he became professor of spectroscopy at Yerkes Observatory at the University of Chicago, where he remained until 1948. In 1948 he returned to Canada as the principal research officer and then director of the Division of Physics at the Canadian National Research Council. In 1955 the Division of Physics of the Canadian National Research Council was split into two divisions, pure and applied physics and Herzberg remained president of the pure physics division. In 1969 he was made distinguished scientist of the recombined Division of Physics of the Canadian National Research Council.
Herzberg's research dealt with spectroscopy and determining molecular geometries using spectroscopy. From his doctoral thesis, on the spectrum of nitrogen gas, and throughout his career he determined spectra of various chemicals and from these data he was able to determine their geometry. Because of Herzberg's work spectroscopy is a tool that chemists can use to determine the identity of a chemical. Different molecules absorb and emit characteristic wavelengths of electromagnetic radiation determined by their structure. Chemists use these characteristic absorbancies and emissions to determine the structure and identity of molecules. At Yerkes Observatory Herzberg applied his knowledge of spectroscopy to determine the gasses present in planetary atmospheres. He is author of the four volume Molecular Spectroscopy and Molecular Structure which has been called the spectroscopist's bible. In 1971 Herzberg was awarded the Nobel Prize in chemistry for "his contributions to the knowledge of electronic structure and geometry of molecules, particularly free radicals".
Other honors won by Herzberg include election to the Canadian National Academy of Science in 1939 and the Royal Society of London in 1951. Other awards won by Herzberg include the Willard Gibbs Award from the American Chemical Society, the Order of Canada, and the Royal Medal from the Royal Society of London.
Herzberg died on March 3, 1999 at the age of 94.
Interview of Gerhard Herzberg by Brenda J. Weinnwisser on February 28 and March 2, 1989, Niels Bohr Library and Archive, American Institute of Physics, aip.org.
Black, Harry; Canadian Scientists and Inventors: Biographies of People Who Made a Difference; Pembroke Publishers Ltd.; 1997
Devorkian, David; "Gerhard Herzberg, 1904-1999"; Bulletin of the American Astronomical Society; (2000)35:1669-1670
Gerhard Herzberg Nobel Biography
Gerhard Herzberg Wikipedia Entry
Sunday, December 18, 2011
At Columbia Armstrong studied under inventor Micheal Pupin and during his junior year invented the regenerative circuit. The regenerative circuit was an improvement on the audion, a radio tube circuit that was used in wireless receivers and invented by Lee DeForest. With the audion the receiver signal was weak and required the use of headphones in order to hear the broadcast. Armstrong's regenerative circuit amplified the signal and loudspeakers could be used to listen to the broadcast. The regenerative circuit could also be used to create radio transmitters. Armstrong graduated with a engineering degree in 1913 and filed for a patent for the regenerative circuit. After graduation he stayed at Columbia teaching and working as Pupin's assistant.
During the first world war Armstrong served in the United States Army Signal Corps. He was sent to Paris, France where he worked to intercept enemy shortwave radio signals setting up his receiver on the Eiffel Tower. While serving in the Army he developed his second major invention, the superheterodyne circuit, which made radio receivers easier to tune and is still used today. Armstrong rose to the rank of major and was awarded the French Legion of Honor ribbon. After the war he returned to Columbia where he eventually succeeded Pupin and in 1920 he sold the rights to his two inventions to Westinghouse. He also sold the rights for another invention, the super regenerative circuit, to newly founded RCA for a large block of stock.
As the 1920s wore on Armstrong increasingly became involved in patent infringement lawsuits. Lee DeForest filed a patent on the regenerative circuit a year after Armstrong's patent and sold the rights to AT&T. AT&T sued Armstrong and the case went through a dozen courts eventually reaching the United States Supreme Court, where Armstrong lost his case due to the justices' misunderstanding of technical details of the circuit. The Institute of Radio Engineers, which had awarded its first gold medal to Armstrong, refused to accept the verdict and take back its medal.
While the legal battle continued Armstrong was working on another invention. Instead of using radio wave amplitude modulation (AM radio) for tuning he developed a receiver that was tuned by radio wave frequency modulation (FM radio). Frequency modulation reduced background noise allowing for clearer reception. The great depression of the 1930s made it impossible for Armstrong to sell his new invention and it was not until 1940 that Armstrong built the first FM station in Alpine, New Jersey, but it was not for another two years that the Federal Communications Commission allocated frequencies to Armstrong.
FM radio did not take off until after World War II when Armstrong again found his patents infringed. Being ill, bereft of money, and facing another long legal battle Armstrong committed suicide on new years eve of 1954, jumping out the window of his New York City apartment.
Curley, Robert, editor; "Edwin H. Armstrong"; The 100 Most Influential Inventors of All Time; Britannica Educational Publishing; The Rosen Publishing Group; 2009
Lessing, Lawrence P.; "Armstrong Bio" at users.erols.com; originally published in the American Dictionary of Biography published by Charles Scribner Sons; 1977
Edwin Howard Armstrong Wikipedia Entry
Sunday, December 11, 2011
After graduation, with few jobs available to a woman and none that interested her, she returned home. In 1892 she traveled to Europe and with her box camera. The pictures that she took were used to make a book In the Footsteps of Columbus, that was sold as a souvenir at the 1893 Chicago World's Fair. In 1894, after her mother's death, Cannon returned to Wellesly as a graduate student in astronomy. In 1895 she went to Radcliffe College in Cambridge, Massachusetts as student assistant. She received her M.A. from Radcliffe in 1907. In 1896 she was hired by Charles Pickering, the director of the Harvard Observatory, to classify stellar spectra. Pickering was in charge of the project creating the Henry Draper Catalog, a catalog of stellar spectra and had hired a group of women, because their salaries were cheaper then men, to do the calculations necessary to determine the position of a star.
Not long after the project started there arose a question of how to classify stellar spectra. Williamena Fleming ,who was in charge of the group of women working for Pickering, wanted a simple classification system and Antonia Draper, the niece of Henry Draper, wanted a more complex system. Cannon incorporated the work of these women in developing her own system, which became the Harvard Stellar Classification System. The letters O,B,A,F,G,K,M (memorized by astronomy students using the mnemonic "oh be a fine girl/guy kiss me") are the classification system developed by Cannon, starting with O for the hottest, blue-white stars, B for blue stars, A for white stars, F for yellow-white stars, G for yellow stars, K for cooler orange stars and M for the coolest red stars. This system, with some modifications, is still used today. Her work, with classifications of 225,000 stars, was published in the 9 volumes of the Henry Draper Catalog.
In 1911 Cannon succeed Fleming as the curator of astronomical photographs at Harvard Observatory. In 1938 she was named the William Cranch professor of Astronomy. She was the first woman to receive a doctorate in astronomy from Groningen University in 1921 and the first woman to receive a honorary doctorate from Oxford in 1925. In 1931 she received the Henry Draper Medal from the National Academy of Science. She was the first woman elected as an officer in the American Astronomical Society and has a crater on the moon named for her. The Annie Jump Cannon prize is awarded every year by the American Astronomical Society for outstanding contribution by women astronomers, within five years of their doctorate. She retired in 1940 but continued working at Harvard Observatory.
She died on April 13, 1941.
Hennessey, Logan; "Annie Jump Cannon (1863-1941)"; available at Wellesly.edu
Kuiper, Kathleen, editor; "Annie Jump Cannon" in The 100 Most Influential Women of All Time, The Rosen Publishing Group; 2009
Annie Jump Cannon Wikipedia Entry
Sunday, December 4, 2011
After graduating he worked for his father as an assistant and obtained his masters degree in 1840, after which he was made a lecturer and began teaching classes in addition to research. In 1838 with his father he became editor of the American Journal of Science and Arts a position he held until his passing. In 1846 he was made professor of chemistry and kindred sciences at Yale. With J.P. Norton he organized the School of Applied Chemistry in 1846, setting up a laboratory at their own expense in a house on the college grounds that had formally been the home of college presidents. The school was enlarged a year later and became the Yale Scientific School and later the Sheffield Scientific School. He remained teaching at Yale until his death.
Sillman's research involved applied chemistry and in 1855 he was given a sample of crude Pennsylvania rock oil by speculators to find out if it could be used for illumination. At the time coal oil and a diminishing supply of whale oil were used in lamps for light. Sillman fractionally distilled (a process invented by his father) the rock oil sample separating it into various samples which he tested for illumination power. Fractional distillation is used to separate constituents of a mixture that have evaporation points that are close together and a special column filled with glass beads or metal pieces that allow vapor to condensate is used. As the mixture is heated vapor moves up the column and the less volatile constituents of the mixture condensate on the glass or metal, allowing only the most volatile constituents to move to the top of the column. A second condensation column is then used to collect the components. Fractional distillation on an industrial scale is done today on crude oil to make gasoline and other fuels. Sillman's experiment produced a product that burned brighter than other fuels on the market at the same price. He described the crude oil to the investors as "a raw material from which...they may manufacture a valuable product." In his report he also said that the distillation products of rock oil might also be useful for lubrication. His report led to an oil boom in Pennsylvania.
With his report Sillman's advice was sought out as a mining consultant, a field in which he was not as successful. He served as secretary to the American Association of Geologists and Naturalists. The United States Congress named him as an original member to the National Academy of Sciences and he was in charge of the mineralogical and geological departments of the New York World's Fair in 1853.
He died on January 14, 1885.
Wright, Arthur W.;"Biographical Memoir of Benjamin Stillman Jr. 1816-1885"; Biographical Memoirs Vol. 7; National Academy Press; 1911
Anonymous; "Benjamin Stillman"; in Memorial Biographies of the New England Historical Genealogical Society: 1880-1889; New England Historical Genealogical Society; 1907
Benjamin Stillman Jr. Wikipedia Entry