Gerhard Herzberg

Gerhard Heinrich Friedrich Otto Julius Herzberg was born on December 25, 1904 in Hamburg, Germany.  His father was a businessman and worked for a small shipping company.  He died when Herzberg was still young.  After his father's death he lived briefly with his uncle in Frankfurt, but he did poorly in school and was homesick so he returned to live with his mother.  In Hamburg he attended the Realgymansium de Johanneums, where he had excellent teachers and developed an interest in astronomy and atomic physics.  He studied astronomy by reading textbooks from public libraries and with a friend made a crude telescope, but he was unable to pursue a career in astronomy for financial reasons.  With a fellowship from industrialist Hugo Stinnes he was able to attend the Technische Universtat Darmstadt, graduating with a Dr.Ing. in 1928.  After graduation he did postdoctoral work at Gottengen University and Bristol University under James Franck, Max Born and John Lennard-Jones.

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.


References:

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

Edwin Howard Armstrong

Edwin Howard Armstrong was born on December 18, 1890 in the Chelsea neighborhood of New York City.  His father was the president of the American office of Oxford University Press and his mother was a former school teacher.  Armstrong was a shy child who was interested engines and other mechanical things.  In 1902 he moved with his family to Yonkers, New York.  A case of rheumatic fever left him with a tic in one eye.  At age 14, inspired by the work of Guglielmo Marconi, Armstrong decided at he would be an inventor and built a wireless apparatus in the attic of his family's home and constructed a 125 foot tall antenna mast on his family's lawn.  Armstrong attended public schools in Yonkers, graduating from Yonkers High School.  After graduation he commuted by motorcycle to the engineering school at Columbia University.

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.


References:

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

Annie Jump Cannon

Annie Jump Cannon was born on December 11, 1863 in Dover, Delaware, the first of three daughters.  Her father, Wilson Cannon, was a shipbuilder and a Delaware state senator.  It was her mother, Mary Jump, Cannon's second wife, who sparked young Annie's interest in astronomy when she taught her the constellations. Cannon was hard of hearing, but she was able to attend Wilmington Conference Academy and then Wellesley College, in Wellesley Massachusetts where she studied physics and graduated in 1884.  The cold weather of Massachusetts left Cannon often sick and one winter she suffered scarlet fever, which left her deaf in one ear.  At Wellesley she also learned the new art of photography.

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.


References:

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

Benjamin Sillman Jr.

Benjamin Sillman Jr. was born on December 4, 1816 in New Haven Connecticut.  His father, Benjamin Sillman Sr. was a professor of chemistry at Yale College in New Haven and his grandfather was General Gold Selleck Sillman, who served in the American Revolution, winning distinguished service defending the southeast corner of Connecticut. Visiting scientists often came to the Stillman home and Benjamin Jr. grew up in a home with the atmosphere of scientific culture.  As a child he collected minerals and became interested in chemical experiments.  He attended the schools of New Haven and in 1833 he entered Yale College, graduating in 1937.

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.


References

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

Sir Charles Scott Sherrington

Sir Charles Scott Sherrington was born in Islington, London, England on November 27, 1857.  Sherrington was the illegitimate son of Anne Brooks Sherrington and Caleb Rose, an imminent Ipswich surgeon.  Caleb Rose and Anne Sherrington were married only in 1880 after the  death of his wife.  Rose was a patron of the arts and the house that Sherrington grew up in had many books and paintings.  In 1871 Sherrington entered Ipswich school, where he played soccer and was an outstanding athelete.  He began his medical training at the urging of his step-father at St. Thomas Hospital in 1876 and passed the preliminary medical examination of the Royal College of Surgeons in 1878.  A year later he passed the examination for a fellowship from the Royal College of Surgeons.  In 1879 he went to Cambridge as a non-collegiate student and began studying physiology under Sir Michael Foster.  The following year he entered Gonville and Caius College, Cambridge.

Sherrington was a good student and earned the highest marks in his class in botany, human anatomy and physiology.  He earned membership in the Royal College of Surgeons in 1884 and earned a first class in the Natural Science Tripos and earned a M.B. Bachelor of Medicine and Surgery in 1885.  In 1886 he earned the title of Licentiate of the Royal Collage of Physicians.  During the winter of 1884-5 he worked for German physiologist Friedrich Goltz in Strasbourg, Germany.  In 1885 he served as part of a committee that went to Toledo, Spain to investigate a potential vaccine for cholera.  The vaccine turned out to be ineffective.  Later that year he went to Berlin to work for Rudolf Virchow, studying the cholera specimens gathered in Spain.  Virchow sent Sherrington to Robert Koch for a class on technique.  Sherrington stayed with Koch for a year and studied bacteriology.  In 1886 Sherrington went to Italy to investigate a cholera epidemic.

In 1887 Sherrington was elected as a fellow at Caius College and appointed lecturer in systematic physiology at St. Thomas Hospital Medical School.  In 1891 Sherrington was appointed superintendent of the Brown Institute for Physiological and Pathological Research at the University of London.  Sherrington's research topics included leukocytes, the specific gravity of blood, the presence of bacteria in secretions and changes in blood in local inflammation. He was also able to cure his nephew from diphtheria by injecting him with anti-toxin.  This is the first recorded case of the successful use of anti-toxin in diphtheria treatment in England.  He also researched spinal reflexes, which laid the basis of the work for which he is most remembered.  In 1895 he was appointed as the Holt Professor in physiology at Liverpool University.  He continued his research into spinal cord innervation and the innervation of opposing muscles.

In 1906 Sherrington published The Integrative Action of The Nervous System, a book so important in neurophysiology that its influence has been compared to Newton's Principia's importance to physics.  In the book he introduced the term synapse to describe the space between nerve cells.  Nerve cells function to carry action potentials, a wave of electrochemical energy, that move down nerve cells.  Synapses, the spaces in between nerve cells, carry the impulse from one cell to the next by means of a chemical neurotransmitter.  When the action potential reaches the end of one nerve cell (called dendrites) that cell releases a neurotransmitter that signals the next cell to fire an action potential.  The neurotransmitter diffuses across the synapse and is detected by receptors on the second nerve cell.  In response to the neurotransmitter being detected by the receptor the second nerve cell fires, sending an action potential down the nerve.  For his work in elucidating the structure and function of the nervous system Sherrington shared part of the 1932 Nobel Prize for physiology and medicine.

In 1913 he was offered the Waynflete chair in physiology, where he remained until his retirement 1936.  During World War I, when his classes were reduced he worked at a shell factory and studied fatigue, particularly industrial fatigue.  Other honors won by Sherrington include election to the Royal Society in 1893 and he served as its president in the early 1920s.  He won the Royal Medal from the Royal Society in 1905, the Knight of the Grand Cross in the Most Excellent Order of the British Empire in 1922 and Order of Merit in 1924.

He spent his retirement in a house he built in his boyhood home, Ipswitch, keeping an active correspondence with many of his former students. He died on March 4, 1952


References:

O'Connor, W.J.; British Physiologists 1885-1914: A Biographical Dictionary; Manchester University Press ND; 1991

Pearce, J.M.S.; "Sir Charles Scott Sherrington and the Synapse"; Journal of Neurology, Neurosurgery, and Psychiatry(2004)75:544

Charles Scott Sherrington Wikipedia Entry

Sir Charles Scott Sherrington Nobel Biography

Edwin Powell Hubble

Edwin Powell Hubble was born on November 20, 1889 in Marshfield, Missouri in the home of his maternal grandparents.  A year later his parents John Powell and Virginia Lee Hubble moved to Marshfield.  His father worked in insurance and often moved with his wife and children and rented out the family's house in Marshfield.  In 1895 Hubble moved back into the family home in Marshfield with his mother and siblings, where he started school.  In 1901 the family moved to Wheaton, Illinois, where Hubble went to middle and high school.  In school Hubble was a good athlete and did well in all his subjects, excepting spelling.  Young Hubble was an avid reader and enjoyed the novels of Jules Verne.  In 1906 Hubble began at the University of Chicago, where he earned his bachelors in mathematics and astronomy in 1910.

After finishing his bachelors Hubble went to England, where he studied law, at the insistence of his dying father, at Queens College, Oxford on a Rhodes Scholarship.  He remained in England for three years.  Upon returning to the United States Hubble taught high school mathematics, physics and Spanish, also coaching basketball, for a year.  After a year teaching he returned to his passion, astronomy, and began studying at the Yerkes Observatory at the University of Chicago, finishing his Ph.D. in 1917.  His dissertation was titled "Photographic Investigations of Faint Nebulae"  Hubble served in the United States Army during World War I, rising to the rank of major.  In 1919 Hubble accepted a position at the Mt. Wilson Observatory, in Pasadena, California, where he remained on staff until his death.  During World War II Hubble  worked for the Army at the Aberdeen Proving Ground, in Aberdeen, Maryland, where he worked on ballistics and for which he was awarded the Legion of Merit.

Hubble's arrival at the Mt. Wilson Observatory coincided with the instillation of the Hooker Telescope, a 2.5 meter telescope, which at the time was the largest in the world.  At the time most astronomers believed that the Milky Way Galaxy was the extent of the universe and that the fuzzy objects called nebulae were contained within it.  Using the Hooker Telescope, Hubble was able to show that some of these fuzzy objects contained stars and were much too distant to be inside of the Milky Way.  Hubble showed that some of these objects were in fact galaxies and he devised a method of categorizing them based on their shape, called the Hubble Sequence, which is still used today classify galaxies.  Hubble's most astonishing discovery came from studying the spectra of 46 galaxies in which he showed that the further galaxies were from each other the faster that they were moving away from each other.  Based on this observation Hubble concluded that the universe was expanding at a constant rate (it later was determined that the rate of expansion is actually increasing).  With his colleague Milton Humason, he estimated that the rate of expansion is 500 Km per second per megaparsec.  So a galaxy one megaparsec away is receding from the Milky Way at a rate of 500Km/second (a mega parsec is one million parsecs, each 3.3 light years or about 3.08x10²²meters).  This is called the Hubble Constant and astronomers have been refining the measurement ever since.

Honors won by Hubble include the Bruce Medal, awarded by the Astronomical Society of the Pacific, the Franklin Medal, awarded by the Franklin Institute, and Gold Medal, the highest honor of the Royal Astronomical Society of Great Britain.  He was never awarded the Nobel Prize because it was not till after his death that astronomy was considered a subject for which the Nobel Prize in physics could be awarded and the Nobel Prize is not awarded posthumously. In addition to the Hubble Space Telescope, a telescope orbiting the earth, an asteroid and a crater on the moon are also named after Hubble.  In 2008 the United States Postal Service issued a stamp honoring Hubble.

Hubble died on September 23, 1953.


References:

Christianson, Gale E.; Edwin Hubble: Mariner of the Nebulae; University of Chicago Press; 1996

Anonymous; Edwin Hubble Biography at edwinhubble.com

Anonymous: Edwin P. Hubble at Hubble Space Telescope Website (hubble.nasa.gov)

Edwin Hubble Wikipedia Entry

Edward Adelbert Doisy

Edward Adelbert Doisy was born on November 13, 1893 in Hume, Illinois.   His father, Edward, was a traveling salesman and his mother Ada was a homemaker.  He went to the University of Illinois, where he earned his bachelors in 1914 and his masters in 1916, both in chemistry.   From 1915 until 1917 he was a biochemistry assistant at Harvard University and from 1917 to 1919 he served in the U.S. Army Sanitary Corps.  Starting in 1919 he taught biochemistry at Washington University in St. Louis, Missouri and he finished his Ph.D., from Harvard University, in 1920, with his thesis research on methods of detecting nitrogen containing biochemicals in blood, including creatine, creatinine and uric acid.  In 1923 he was named the head of the biochemistry department at St. Louis University, in St. Louis, Missouri, where he remained for the rest of his career.

With Edgar Allen, his research assistant, Doisy investigated the mouse estrous cycle and by 1936 they succeed in isolating all three estrogens (esterone, esterdiol and estratiol) from human urine (while collecting samples, one driver committed a traffic violation and was pulled over by a policeman, who when seeing the bottles of amber liquid in the car, believed that the driver was a bootlegger).  Doisy followed the work of Danish researcher Henrick Dam, who had grown baby chickens on an artificial diet that contained no fats, and found that they were prone to hemmoraging. Dam also found this could be cured by a diet of hempseed, and was able to isolate the active principal.  Doisy, with the assistance of graduate assistant Ralph McKee, was able to isolate two forms of this chemical (named K1 and K2).

Vitamin K, first reported by Dam, is short for Koagulationsvitamin, the German name given to it.  Vitamin K functions to modify proteins by adding a carboxy group certain glutamine residues forming gamma-carboxyglutamate, which allows the protein to bind calcium.  These modified proteins take part in the blood coagulation cascade and bone metabolism.  Like other fat soluble vitamins (A and D) it is stored in fat tissue in the human body.  Newborns are injected with a dose of vitamin K to prevent hemmoraging.  It is found in green leafy vegetables such as spinach and Swiss chard and fruits including avacado, grapes, and kiwi fruit.  For their work in discovering vitamin K, Doisy and Dam were awarded the 1943 Nobel prize in physiology or medicine.

Other awards won by Doisy include honorary degrees from Yale, Washington, Chicago, Illinois, St Louis, Gustavus Aldolphus College, and Paris Universities.  He served on the League of Nations Committee for the Standardization of Sex Hormones in 1932 and 1935.  He was president of the American Society of Biological chemists from 1943 to 1945, the Endocrine Society from 1948 to 1950 and the Society of Experimental Biology and Medicine from 1950 to 1951.  In 1955 the biochemistry department of St. Louis University was named after him.  He retired in 1965.

He died on October 23, 1986.


References:

Carey, Charles W.; American Scientists; Infobase Publishing; 2006

Simoni, Robert D., Hill, Robert L., and Vaughn, Linda; "The Discovery of Esterone, Esterol, and Esterdiol and the Biochemical Study of Reproduction.  The Work of Edward Aldebet Doisy"; The Journal of Biological Chemistry(2002)277:e7

Edward A. Doisy Nobel Autobiography

Edward Aldebert Doisy Wikipedia Entry

James Gregory

James Gregory was born on November 6, 1638 in Drumoak, Scotland.  His father was a minister and died when Gregory was thirteen.  His mother, whose uncle was a professor of mathematics, schooled the boy in geometry and had him attend grammar school in Aberdeen, Scotland.  With his father dead, his education was seen to by his older brother David and he attended Marischal College in Aberdeen, graduating in 1657.  Gregory studied optics and in 1663 published Optica Promota in which he described for the first time the construction of a reflecting telescope, also called a Gregorian telescope, honoring Gregory.  He was not able to construct one because he did not have the skills required to prepare the mirrors.

A reflecting telescope is an optical telescope that uses one or more curved mirrors to reflect light from the object being viewed.  It was invented as an alternative to a refracting telescope, in which light passes through lenses.  Refracting telescopes suffer from the problem of chromatic aberration, in which, due to the fact that different colors of light have different indices of refraction through glass, some details can be blurry and show color blotches.  An index of refraction is the ratio of the speed of light through a vacuum over the speed of light through a particular medium, in this case glass, and can used to determine how far a light beam is bent when it travels through one medium to another. The effect of the differences in the indices of refraction is that different colors will have different focal lengths for a particular telescope. Today nearly all large research-grade telescopes are reflecting telescopes.  Without lenses, they do not suffer from chromatic aberration and have a wider spectrum of color, due to the fact that some wavelengths of light (particularly UV light) are absorbed by glass lenses.  Another advantage of reflecting telescopes is that they can be made larger than refracting telescopes.  The largest lens that can be practically created is only 1 meter in diameter, whereas reflecting telescope mirrors have been created that exceed 10 meters in diameter.

In 1663 Gregory went to London, England where he met some members of the Royal Society, including John Collins, Robert Hooke, and Sir Robert Moray.  These friends introduced him to an optician named Rieve, who attempted to construct a telescope using Gregory's design, but he was unable to make the parabolic mirror to work to Gregory's satisfaction.  Isaac Newton read Gregory's book and the two later corresponded.  At that time the European continent was considered the center of mathematics research so in 1664 he left London for Padua, in the Venetian Republic, where he studied mathematics and published two works on proto-calculus, which bolstered his reputation and got him into the Royal Society when he returned to London in 1668.  In 1669, with the help of Robert Hooke, he was appointed to a new chair in mathematics at the University of St. Andrews.  He taught at St. Andrews for 6 years but did not enjoy his time there.  Suspicious of his new ideas and his interest in higher mathematics his masters at the school shunned him and eventually withheld his salary and servants.  

In 1674 he accepted a new professorship at the University of Edinburgh.  At Edinburgh the university officials were more generous and he had the money he needed to establish an astronomy program.  Sadly, in October of 1675 he suffered a stroke while he was showing the moons of Jupiter to his students.  He died a few days later at the age of 37.  

References:

Chambers, Robert; "Biographical Dictionary of Eminent Scotsmen"; Volume 2; Blackie and Son, 1835

O'Connor JJ and EF Roberson; "Gregory Biography"; at history.st-andrews.ac.uk

Anon; "Biographical Information" for Gregory, James, at nahste.ac.uk

James Gregory Wikipedia Entry

Daniel Nathans

Daniel Nathans was born on October 30, 1928 in Wilmington, Delaware.  He was the youngest of nine children of Russian immigrant parents.  His father lost his business in the great depression and for some time was unemployed (he later learned that his parents sometimes went hungry in order to feed the children).  His early education was in Wilmington public schools, working in the afternoon and weekends, and he attended the University of Delaware, hitchhiking to get to class, and graduating with a chemistry degree in 1950.  Following his father's wishes Nathans went to medical school at Washington University in St. Louis, Missouri.  During a summer job, working at a Delaware hospital he was bored with the routine nature of medical practice and when he returned to St. Louis he began working in the research lab of Oliver Lowery.  He graduated medical school in 1954.

After graduating he did an internship at Columbia-Presbyterian Hospital in New York City and spent two years as a clinical associate at the National Cancer Institute where he cared for patients and researched the synthesis of immunoglobulins by myeloma tumors. He returned to Columbia-Presbyterian for two more years and then began his research career at the Rockefeller Institute working for Fritz Lippman in 1959, where he studied bacterial protein synthesis.  Nathans began a Ph.D. program but did not complete it because he did not want to sit in any more lectures. In 1962 he moved to Johns Hopkins University in Baltimore, Maryland and worked for Barry Wood, who had been his teacher in medical school at Washington University.  In 1969 he went to the Weizmann Institute of Science in Rehovot, Israel to learn about animal viruses and while he was there he received correspondence from his colleagues at Johns Hopkins about a restriction endonuclease enzyme.  When he returned to America, Nathans, with the assistance of his graduate student Kathleen Danna, continued work that further established the function of restriction endonuclease enzymes.

Restriction endonucleases or restriction enzymes are enzymes that cleave double stranded DNA molecules at specific base sequences.  Each enzyme has its own specific recognition sequence, that is a particular sequence of base pairs where it cuts the DNA molecule.  These enzymes are used by bacteria to protect themselves from viruses.  The enzyme with cleave viral DNA but leave the host DNA, which is methylated, alone.  Over 6000 restriction enzymes have been now been characterized. These enzymes have been used to study genetics and find the locations of particular genes.  They are also used in genetic engineering and the insertion of genes into genomic DNA.  For his work characterizing restriction enzymes Nathans was awarded the 1978 Nobel Prize in Medicine, along with Hamilton Smith, who had made the initial discovery, and Werner Arber who had predicted the existence of restriction enzymes.

Other honors won by Nathans include election to the National Academy of Science and its U.S. Steel Foundation Award in Molecular Biology.  Johns Hopkins has honored him co-naming the McKusick-Nathans Institute of Genetic Medicine after him as well as one of its medical school's colleges.

Nathans died on November 16, 1999.


References:

DiMaio, Daniel, "Daniel Nathans: October 30, 1928 - Novermber 16, 1999"; Biographical Memiors Vol. 79, National Academy Press (2001)

Brownlee, Christian; "Danna and Nathans: Restriction Enzymes and the Boon to Modern Molecular Biology"; Proceedings of the National Academy of Science (2005)102:5909

Daniel Nathans Wikipedia Entry

Danile Nathans Nobel Autobiography

Felix Bloch

Felix Bloch was born on October 23, 1905 in Zurich, Switzerland.  His father, Gustav Bloch was a wholesale grain seller in Zurich.  He entered public elementary school at age 6 and initially had trouble in school because he spoke Swiss German with an accent different than those of his peers.  In 1918 he began attending gymnasium run by the canton of Zurich.  Young Bloch excelled in mathematics and science and in 1924 he passed his "matura" an exam that allowed him to go on to an institution of higher learning.  Initially planning to study engineering he entered Federal Institute of Technology in Zurich.  After a year he changed his mind and began to study physics and continued at the same institution, graduating in 1927.

After graduating he went to the University of Lepzig, where he studied under Werner Heisenberg, completing his Ph.D. in 1928.  His doctoral thesis introduced the concept of Bloch waves to explain the behavior of electrons in crystals, developing the theory of metallic conduction.  After finishing his doctorate he took a tour of the various centers of experimental physics in Europe working for Wolfgang Pauli at the University of Zurich, Niels Bohr in Copenhagen, and Enrico Fermi in Rome, before returning to the University of Lepzig as a lecturer in physics.  In 1933, soon after Hitler came to power in Germany, he emigrated to the United States, taking a position at Stanford University in Palo Alto, California.  Bloch became Stanford's first professor of theoretical physics in 1939.  During World War II he worked on nuclear power at Los Alamos Nuclear Laboratory and on ways to interfere with radar at Harvard University.  After the war he returned to Stanford.

Bloch is most famous for his work developing the theory of nuclear induction and magnetic resonance.  Atoms that have an uneven number of protons and/or neutrons have an intrinsic magnetic moment and angular momentum.  This is called spin.  When placed into a magnetic field nuclei will emit electromagnetic radiation, as their spin lines up with the magnetic field.   The frequency of this emission depends on the strength of the magnetic field and the isotope.  By measuring these emissions it is possible to determine the chemical structure in which the atom resides.  This technique is used by chemists to determine the structure of compounds and it is used in medical imaging and is called magnetic resonance imaging, or MRI (the name was changed to remove the word "nuclear").  For his discovery of nuclear magnetic resonance Bloch won the Nobel Prize for physics in 1952, which he shared with Edward Mills Purcell who developed the theory simultaneously.

In 1952 Bloch became the first director of CERN, the European Organization for Nuclear Research, and he formulated its early policies regarding atomic research.  Because as director he had little time for research he returned to Stanford a year later.  In 1965 he served as president of the American Physical Society.

Bloch died on September 10, 1983.


Bibliography:

Hofstader, Richard; "Felix Bloch"; Physics Today (1984)37:115-116

Hofstader, Richard; "Felix Bloch: 1905-1983" in Biographical Memoirs Vol. 64; National Academy Press; 1994

Felix Bloch Nobel Biography

Felix Bloch Wikipedia Entry

Max von Laue

Max von Laue was born on October 9, 1879 in Pfaffendorf (now part of Koblenz), Germany.  Von Laue's father was an official in the German military and his family moved often.  His bookish nature was recognized by his family and his grandfather gave him science books.  A demonstration of the electrical deposition of metallic copper from a solution of copper sulfate fascinated young von Laue and paved the way for a career in physics.  He attended gymnasium school in Posen, Berlin, and Strasbourg.  After a year of military service he attended the University of Strasbourg, the University of Gottingen, and the University of Munich, studying mathematics, chemistry and physics.  He earned his doctorate under Max Planck at the University of Berlin, graduating in 1903.

After finishing his doctorate he spent two years at the University of Gottingen and then went back to work for Max Planck as an assistant at the Institute for Theoretical Physics in Berlin.  There von Laue met and became friends with Albert Einstein and von Laue contributed to the development and acceptance of Einstein's theory of relativity.  In 1909 he went to the University of Munich where he lectured on thermodynamics, optics, and relativity.  In 1912 he was appointed professor of physics at the University of Zurich.  In 1913 his father was raised to the ranks of hereditary nobility and the "von" was added to his name.  From 1914 to 1919 he was professor of physics at the University of Frankfurt and in 1916 he worked at the University of Wurzburg on vacuum tubes for use in military wireless communications.  In 1919 he went till the University of Berlin, where he remained until 1943, when he became an emeritus, with his consent, one year before the mandatory retirement age.

Von Laue is most famous for the discovery of the diffraction of  x-rays by crystals. The discovery originated from a discussion of the behavior of light moving through a regular crystalline medium.  This caused von Laue to wonder what affect crystals would have on the much shorter wavelength x-rays.  After the diffraction of x-rays by crystals was demonstrated von Laue worked the results out mathematically and published his results in 1912.  This discovery paved the way for x-ray crystalography, the study of molecular structure of crystals using x-rays.  For his discovery von Laue was awarded the Nobel Prize in physics in 1914.  Other honors won by von Laue include the Max Planck Medal in 1932 and being made and officer in the French Legion of Honor in 1957.

Von Laue opposed the rising National Socialism movement in Germany and worked to help Jewish scientists emigrate from Germany.  When Germany invaded Denmark in 1940 von Laue's golden Nobel Prize was dissolved in aqua regia by Hungarian chemist Georg de Hevesy, who was working at the Niels Bohr Institute at the University of Copenhagen where the prize was being kept, in order to prevent it falling into Nazi hands.  Had the prize been discovered von Laue would have faced prosecution for exporting gold out of Germany.  After the war de Hevesey found the solution, where he left it, of on the shelf of his laboratory.  He precipitated the gold and returned it to the Nobel Society which recast the prize.  After World War II von Laue was was seized by Operation Alsos, an Anglo-American operation to grab German nuclear scientists and materials, to prevent them from falling into the hands of the Soviets, and he was interred in Huntington, England at Farm Hill, a bugged house, with nine other German scientists.  He returned to Germany in early 1946 and was the only German scientist invited to attend a conference on crystalography in London, where he was allowed to wander at will only four months after being released from internment.  After the war von Laue worked to reestablish German science and he served as the director of the Max Planck Institute for Physical and Electrochemistry from 1951 to 1959.

On April 8, 1960, while driving to the laboratory, von Laue was involved in a automobile accident with a motorcyclist, who had just received his licence.  Although he showed initial signs of recovery, he died on April 20th.

References:

Von Laue, Max; My Development as a Physicist: An Autobiography, at iucr.org

Max von Laue Nobel Biography

Max von Laue Wikipedia Entry

Thomas Hunt Morgan

Thomas Hunt Morgan was born on September 25, 1866 in Lexington, Kentucky.  He was the eldest son of Charlton Hunt Morgan who served as the American Consul in Messina, Sicily in 1860, where he assisted Garibaldi during the uprising that started his campaign of that year.  He later joined the Confederate Army  was wounded at the Battle of Shiloh.  Morgan as a boy was interested in natural history and spent several summers in the mountains near Oakland, Maryland where he collected fossils.  When he grew older he spent his summers in the mountains of Kentucky doing geological and biological field work.  He graduated with a BS from the University of Kentucky in 1886.

Morgan received his Ph.D. from Johns Hopkins in 1890.  After which he received the Bruce Fellowship which allowed him to study in Italy at the Marine Zoological Laboratory in Naples.  In 1891 Morgan was appointed associate professor (and head of the biology department) at Bryn Mawr University, where he stayed until 1904.  While at Bryn Mawr he met and married Lillian Vaughan Sampson, who would later contribute to his research.  In 1904 Edmund Wilson, who Morgan had replaced at Bryn Mawr, invited him to Columbia University where he was appointed professor of experimental biology.  He remained at Columbia until 1928 when moved to the California Institute of Technology, in Pasadena, California, where he was appointed professor of biology and director of the Kerckhoff Laboratories.  While at Caltech he established a marine laboratory at Corona Del Mar, California.  He remained at Caltech until 1945.

Morgan's research at Columbia, influenced by Wilson, looked at the role of cytology in influencing biological systems.  He worked with fruit flies (Drosophila melanogaster) to study genetics.  Although he was initially skeptical of the theories of Gregor Mendel, Morgan used fruit flies to show how certain traits are linked, that is the genes which are responsible for them are located on the same chromosome.  From his experiments he was able to make maps of the Drosophila chromosomes, showing the locations of various genes.  Drosophila have become a common model organism used for studying genetics.  For his work showing the importance of chromosomes in heredity Morgan was awarded the 1933 Nobel Prize for Physiology and Medicine.  Morgan was also interested in embryology and made important contributions to that field including demonstrating that gravity has no effect on a developing egg.

Other honors won by Morgan include membership in the National Academy of Sciences and foreign membership in the Royal Society.  In 1924 he was awarded the Royal Society's Darwin Medal and he has honorary degrees from Johns Hopkins and the University of Kentucky.

Morgan died on December 4, 1945.


References:

Sturtevant, A. H. "Thomas Hunt Morgan: 1866-1945"; in Biographical Memiors; National Academy Press; 1959

Thomas H. Morgan Nobel Biography

Thomas Hunt Morgan Wikipedia Entry

Edwin Mattison McMillan

Edwin Mattison McMillan was born on September 17, 1907 in Redondo Beach, California.  His father Edwin McMillan was a physician.  As a child McMillan was always building gadgets and living in Pasadena, California he was able to attend lectures and get to know the physicists at the nearby California Institute of Technology.  After high school he attended the California Institute of Technology studying physics and chemistry and earning his B.Sc. in 1928 and his M.Sc. one year later.  He earned his Ph.D. at Princeton University in 1932.  His thesis described the behavior of a beam of hydrogen chloride molecules in a non-homogeneous electric field.

After earning his Ph.D., McMillan won a National Research Council fellowship.  At the invitation of Ernest Lawrence he went to the University of California at Berkley where he worked in Lawrence's Berkley Radiation Laboratory.  He became a an instructor in the physics department at Berkeley in 1935, assistant professor in 1936, associate professor in 1941, and professor in 1946.  During the World War II MacMillan worked at the Massachusetts Institute of Technology developing radar, at the U.S. Navy Radar and Sonar Laboratory in San Diego California working on sonar, and he worked on the Manhattan Project in Los Alamos, New Mexico.  He returned to Berkley after the war and with the death of Lawrence in 1958 he became director of the Berkley Radiation Laboratory, later renamed after Lawrence.  He remained director until his retirement in 1973.

McMillan is most remembered for his work in creating the first transuranic elements.  Working at Berkley he used the newly invented cyclotron to bombard uranium with neutrons and deuterium to create neptunium and plutonium.  These elements (atomic numbers 93 and 94) were the first elements created with more protons than uranium, which was thought to have the highest possible number.  Like uranium these elements are subject to radioactive decay.  McMillan and Glenn Seaborg, who finished MacMillan's work when he left Berkley to go to M.I.T., were awarded the Nobel Prize in Chemistry in 1951 for "their discoveries in the chemistry of transuranium elements".  McMillan also used the cyclotron to create other non-naturally occurring radioactive elements including oxygen-18 and beryllium-10.

Other honors won by MacMillan include election to the National Academy of Science in 1947 (he served as its chairman from 1968 to 1971), the Atoms for Peace award in 1963, shared with Vladimir Veksler, for the creation of the synchrotron, and the National Medal of Science in 1990. 

McMillan died on September 7, 1991.


References:

Jackson, David J. and Panofsky, W.K.H.; "Edwin Mattison McMillan: 1907-1991"; Biographical Memoirs Vol. 69; National Academy Press; 1996

Edwin McMillan Nobel Biography

Edwin McMillan Wikipedia Entry

Stanford Moore

Stanford Moore was born on September 4, 1913 in Chicago, Illinois.  His father, Howard Moore, at the time was a law student at the University of Chicago.  His mother was a graduate of Stanford University, where his parents met.  It is alleged that this was the origin of Moore's first name.  Moore began school at age 4 at a progressive school in Winnetka, Illinois.  When he was six his father took a teaching position at the University of Florida Law School.  Later he took a position at Mercer University in Macon, Georgia.  During these years Moore attended public schools.  When his father took a position at the Vanderbilt University Law School, where he remained until his retirement in 1949, Moore attended the Peabody Demonstration School, which was attached to the George Peabody College for Teachers.  Moore attended the school for seven years and was an outstanding student.

Moore attended Vanderbilt University and was initially torn between careers in chemistry and aeronautical engineering.  In his third year he was influenced by Arthur William Ingersoll, and took an interest in organic chemistry and molecular structure.  He graduated from Vanderbilt in 1935 with a BA in chemistry.  He also won the Founder's Medal as the outstanding student in his class.  Moore went to graduate school at the University of Wisconsin where he worked for Karl Link and learned micro analytical techniques.  He graduated in 1938 with a Ph.D. in organic chemistry.  His thesis project was a method for determining which monosacharides were in the polysacharides he was analyzing.  After graduation he took a job as a research assistant working for Max Bergman at the Rockefeller Institute for Medical Research.  During World War II Moore worked for the Office of Scientific Research and Development researching therapeutic agents for mustard gas and other chemical warfare agents. 

After the war he returned to the Rockefeller Institute and worked with William H. Stein on chromatographic methods of determining the amino acid sequence of proteins.  Proteins are macromolecules composed of a sequence of amino acids bound together by peptide (amide) bonds.  Moore and Stein, worked with Christian Anfinsin of the National Institutes of Health, determining the sequence of ribonuclease, an small enzyme of only 124 amino acid residues.  From the determination of the sequence of the amino acids they were able to learn about the active site of the enzyme, where the chemical reaction takes place.  Enzymes are proteins that catalyze chemical reactions, speeding up the biochemical reactions in living organisms.  For their work on the structure of ribonuclease Moore, Stein, and Anfinsen won the Nobel Prize in Chemistry in 1972.

Other honors won by Moore include honorary doctorates from the University of Brussels and the University of Paris, the American Chemical Society award for Chromatography and Electrophoresis, shared with Stein, and the Richards Medal from the American Chemical Society.  Moore remained working at the Rockefeller Institute until his death.

Moore died on August 23, 1982.


References:

Smith, Emil L. and Hirs, C.H.W.; "Stanford Moore: September 4, 1913 - August, 23, 1982"; Biographical Memoirs Vol. 56; National Academy Press; 1987

Stanford Moore Nobel Biography

Stanford Moore Wikipedia Entry 

George Hoyt Whipple

George Hoyt Whipple was born on August 28, 1878 in Ashland, New Hampshire. His father, Ashley Cooper Whipple, and paternal grandfather, Solomon Mason Whipple, were both country doctors. When Whipple was two years old his father died of pneumonia and he was raised by his mother and grandmother. As a boy he enjoyed spending time out doors, hunting and fishing which he did throughout his life. Through prep school and college he earned money for his education during breaks and summers providing help and service to tourists to Squam Lake and Lake Winnepesaukee in New Hampshire. He attended Andover Academy and Yale University, graduating with an A.B. in 1900.

Intending to become a physician like his father and grandfather he took a year off from school and earned money for medical school working at Dr. Holbrook's Military School in Ossining, New York, where he taught mathematics and science and served as an athletics coach. In 1901 he entered Johns Hopkins University Medical School. He did so well in his first year anatomy and physiology classes that he won the chance to serve as a student assistant in those classes in his second year. During medical school Whipple became fascinated with pathology, studying the effects of disease on tissues. He graduated medical school in 1905. Graduating fourth in a class of fifty four, he had his choice of internships and choose to stay at Johns Hopkins as a pathology assistant until 1907.

In 1907 Whipple went to Panama and worked as a pathologist at Ancon Hospital, later named Gorgas Hospital, during the building of the Panama Canal. In 1908 he returned to Johns Hopkins first as an assistant, and later an instructor, a associate and associate professor of pathology. In 1914 he was appointed professor of research medicine and director of the Hooper Foundation for Medical Research at the University of California. He was dean of the University of California Medical school from 1920 to 1921. In 1921 he became the dean of the then newly founded and yet to be built medical school at Rochester University. He he served as dean until 1954 and remained at Rochester University, as a professor of pathology, the rest of his life.

Whipple's research was concerned with anemia and the physiology and pathology of the liver. His experiments with anemic dogs revealed that a diet of liver reversed the effects of the anemia. Whipple found that diets of meat were more effective in curing anemia than vegetable diets, but cooked apricots were surprisingly effective. His research led William Murphy and George Minot to experiment with liver diets for people suffering from pernicious anemia, which cured it. Whipple, Murphy, and Minot were awarded the Nobel Prize in 1934 for "their discoveries concerning liver therapy in cases of anemia". Whipple was also the first to describe Whipple's disease, a rare infectious disease caused by the bacterium Tropheryma whipplei.

Whipple died on February 1, 1976.

References:

Miller, Leon L.; "George Hoyt Whipple: 1878-1976"; Biographical Memiors; National Academy Press; 1995

George Hoyt Whipple, Nobel biography

George Hoyt Whipple, Wikipedia entry

Jean Servais Stas

Jean Servais Stas was born on August 21, 1813 in Leuven, Belgium. His father was a locksmith. Due to his delicate health he was predisposed to an academic career. Initially he trained as a doctor at the University of Leuven, because at the time it was the only field of study at the university that taught laboratory science and he obtained a medical degree in 1835. After graduation he switched to chemistry, working for Jean-Baptiste Dumas. In Dumas' laboratory Stas assisted in the most accurate, at the time, determination of the atomic weight of carbon.

In 1840 Stas was appointed professor at the Royal Military School in Brussels. He continued measuring atomic weights, using Oxygen, at 16, as a standard. He proved that atomic weights for elements were not all multiples of 1, the atomic weight of hydrogen, disproving the theory of English physicist William Prout that all the atomic weights were multiples of that of hydrogen. These careful measurements by Stas helped form the basis of the periodic system developed by Dimitri Mendeleev and other chemists.

The atomic mass of an atom is equal to the number of protons and neutrons found in its nucleus minus a small amount of mass for binding energy. The atomic mass of elements used by chemists today are averages, weighted for the various naturally occurring isotopes of the element. For example chlorine has two naturally occurring isotopes, chlorine-35 and chlorine-37. About 76% of naturally occurring chlorine is chlorine-35, so the weighted average used for chlorine in chemical calculations is 35.45. And this is an example of why Stas, in his measurements, did not always get integer results.

Stas is also responsible for one of the world's first toxicology findings. In 1850 the Belgian authorities requested the help of Stas in providing evidence in the prosecution of Count Bocarme. Bocarme, in order to secure for himself the family fortune, had poisoned his brother-in-law by force feeding him nicotine that he had extracted from tobacco. Stas developed a method for isolating alkaloids from human tissues and was able to isolate nicotine from the corpse of Count Borcame's brother-in-law. Stas' evidence was used in the trial and helped convict Count Bocarme of murder. Honors won by Stas include induction into the Royal Society of London, as a foreign member and the Davy Medal, from the Royal Society, for his researches into atomic weights.

Stas died on December 13, 1891

References:

Stratmann, Linda; "Tobacco and Crime: Linda's Crime Notes"; at visart.be

Timmermans, Jean; "Jean Servais Stas"; Journal of Chemical Education(1938)15:353

Jean Servais Stas Wikipedia Entry

Arthur Jeffery Dempster

Arthur Jeffery Dempster was born on August 14, 1886 in Toronto, Canada. His parents were James and Emily (Cheney) Dempster. As a young man he had a wide field of interest, wining multiple scholarships in different subjects. He went to the University of Toronto, earning bachelors and masters degrees in 1909 and 1910 respectively. His first scientific publication was a paper on Darwin's tidal theory.

In 1911 Dempster went to Germany where he first spent a semester each at the Universities of Munich and Gottingen, then went on to spend two years at the University of Wurzburg studying under Wilhelm Wien. Wien was studying the deflection of positive ion beams by electric and magnetic fields. Dempster began to work on a Ph.D. thesis but his studies were interupted by the outbreak of the first world war. Being a British subject, Dempster was forced to flee Wurzburg and left on the last train carrying civilians before the general mobilization. Another Canadian student who made the choice to stay spent four years in an internment camp. Dempster decided to finish his doctorate at the University of Chicago, where he finished in 1916, graduating summa cum laude.

After briefly serving in the Army during World War I and being naturalized as a U.S. citizen he returned to the faculty of the University of Chicago in 1916 and was made full professor in 1927. Dempster remained at the University of Chicago until his death in 1950. Dempster continued studying positive ion rays and using the properties of these rays in 1918 he developed the first modern mass spectrometer. In 1912 J.J. Thompson had developed a mass spectrometer which he used to show that stable elements have can have multiple isotopes, but it was Dempster who perfected it. His mass spectrometer was over 100% more accurate than Thompson's.

A mass spectrometer is an instrument that seperates chemical species by their atomic weight. A sample put into a mass spectrometer is first vaporized and then ionized (electrons are removed making positive ions). After ionization it is seperated by atomic mass by means of electric and magnetic fields. Because the heavier elements are less easy to move using electric or magnetic fields they can be seperated from lighter elements. Using this instrument in 1935 Dempster discovered uranium-235, an isotope of uranium lighter than uranium-238, which made possible atomic energy. Uranium-235 has only a 0.7% abundance in naturally ocuring uranium.

From 1943 to 1946 Dempster was the chief physicist of the University of Chicago's Metallurgical Laboratory, a laboratory specialy purposed to develop the materials neccessary for the production of atomic weapons. Honors won by Dempster include election to the National Academy of Science, a prize from the American Association for the Advancement of Science, and the Lewis Award from the American Philisophical Society.

Dempster died from a heart attack while vacationing in Florida on March 11, 1950.

References:

Allison, Samuel King; "Arthur Jeffrey Dempster: 1886-1950"; Biographical Memoirs; National Academy Press (1952)

"Arthur Jeffrey Dempster, Physicist, 63, Dead"; New York Times; March 12, 1950

Arthur Jeffery Dempster Wikipedia Article

Germain Henri Hess

Germain Henri Hess was born on August 7, 1802 in Geneva, Switzerland. His family moved to Russia when his father, an artist, became a tutor for a rich family. He studied medicine at the University of Tartu, obtaining a M.D. in 1826. In school he also studied chemistry and geology and upon graduation traveled to Stockholm, Sweden to study under the chemist Jons Jakob Berzelius. Although Hess spent only one month in the lab of Berzelius, they became life-long friends and correspondents.

On his return to Russia, Hess took part in a geological expedition to the Urals. After the expedition Hess set up a medical practice in Irkutsk where he remained for two years. In 1830 Hess moved to St. Petersburg where he began teaching chemistry and doing research. Later he became a professor at the St. Petersburg Technological Institute. He remained in St. Petersburg for the remainder of his life.

Hess is most famous for the chemical law that bears his name: Hess's Law. The law is that the enthalpy of change for a chemical reaction that is carried out in a series of steps is equal to the sum of the enthalpies of change of each of the steps. Enthalpy is the heat generated or lost by a chemical reaction. Hess's law allows for the calculation of how much heat will be released or absorbed by a chemical reaction by summing up the enthalpies of each of the steps of the reaction. Hess's Law was an early law in thermochemistry, the study of energy and heat in chemical reactions.

Other discoveries made by Hess include the discovery that sugar when oxidised yields saccharic acid. The mineral Ag₂Te is named Hessite in his honor. Hess wrote the chemistry textbook that was the standard Russian chemistry text for several decades. He was forced to retire due to failing health in 1848.

Hess died in St. Petersburg on December 13, 1850.

References:

Culp, Bartlow; "Germain Henri Hess"; at chemistry.explained.com

Germain Henri Hesse Wikipedia Entry

Theobald Smith

Theobald Smith was born on July 31, 1859 in Albany, New York. His father, a German immigrant, ran a small tailoring shop. His mother taught him to play the piano at an early age and he was a good student in math. Smith attended public schools in Albany and won a full tuition scholarship to Cornell University. While at Cornell he earned extra money playing a church organ. He graduated from Cornell in 1881.

After graduation Smith initially intended to go into teaching, but he was unable to find a teaching job. His second choice was medicine and so he attended Albany Medical College graduating in 1883. After two years of medical school he did not feel himself ready for clinical practice so he returned to Cornell for graduate school and began working for Daniel E. Salmon at the newly established Bureau of the Animal Industry, which had been set up by the U.S. Congress in 1884 to fight animal diseases. Without any training in microbiology Smith taught himself by reading the papers of Pasteur, Koch, and Virchow. While at the BAI Smith isolated for the first time what came to be called Salmonella (named after Daniel Salmon) and was able to prove that Texas fever, a debilitating cattle disease, was carried by ticks. This was the first discovery of an arthropod borne disease.

In 1895 Smith took over running the Massachusetts State State Antitoxin Laboratory and in 1896 became professor of comparative pathology at Harvard University. While in Boston he continued his research on animal diseases and established that if animals are repeatedly exposed to a bacteria they become hypersensitive to it. This phenomena is known as anaphylaxis. His work on vaccines established that killed bacteria could act to generate immunity to living bacteria and he established that diphtheria could be vaccinated against by combining diphtheria toxin with its anti-toxin in a vaccine. In 1915 Smith left Harvard for the Rockefeller Institute for Medical Research as the head of the Department of Animal Pathology. He remained at the Rockefeller institute until his retirement in 1929.

Smith was considered on of the most notable figures in American medicine at the time. Honors won by Smith include the Copley Medal, awarded by the Royal Society in 1933 and eleven honorary degrees from prestigious universities.

Smith died on December 10, 1934.

References:

Schultz, Myron; "Theobald Smith"; Emerging Infectious Diseases 14:1940-1942 (2008)

Zinsser, Hans; "Biographical Memior of Theobald Smith: 1859-1934" in Biographical Memiors Vol. 17; National Academy Press 1936

Theobald Smith Wikipedia Entry

Sir William de Wiveleslie Abney

Sir William de Wiveleslie Abney was born on July 24, 1843 in Derby, England. His father, Rev. Edward Abney, was vicar of St. Alkmund's in Derby. Abney attended Rossall School and the Royal Military Academy in Woolrich and joined the Royal Engineers at 18, after which he served in India for several years. From his father he inherited a interest in photography and he attended the Military School of Engineering in Chatham in order to learn about it. There he was put in charge of a photography laboratory and he was promoted to captain in 1873. He became and instructor at Chatham in 1874.

While at Chatham Abney participated in the photographic observation of the transit of Venus in 1874 and developed film for infrared photography. Using this film he was able to take a picture of a boiling kettle of water in a completely dark room. He also used it to study the infrared spectrum of stars and developed infrared photography to be used to study the infra red spectrum of organic chemicals.

Infrared light is electromagnetic radiation that has a longer wavelength than visible red light (which is at the long wavelength end of the visible spectrum). It is emitted by hot objects near room temperature. Infrared light is absorbed and emitted by organic molecules as they change their rotational and vibrational states and based on the wavelengths of these absorptions it can be used to identify various compounds.

Abney wrote many books on photography which were the standard texts of the day. He was a member of the Royal Astronomical Society once serving as president and was a member of the Physical Society of London, where he also served as president. He was a member of the Royal Society and was knighted in 1900.

He died on December 3, 1920.

References:

Obituary in the Notices of the Royal Astronomical Society 81:250-254(1921)

Obituary in the British Journal of Opthamology 5:47-48(1921)

Sir William de Wiveleslie Abney Wikipedia Entry

Gilbert White

Gilbert White was born on July 18, 1720 in the village of Selborne, England, while his parents were living in the house of his grandfather, also named Gilbert White, the vicar of Selborne. When White was one year old, his father and mother moved to a house in the village of Compton. Like any other country boy, Gilbert took many walks through nature, although he did not keep diary of his walks. The family moved back to Selborne when he was nine, after the death of his grandfather. At the age of thirteen or fourteen White went to Basingstoke where he studied under the Reverend Thomas Warton. In April 1740 he entered Oriel College, Oxford, graduating in 1743.

He spent the following year at Oriel attending lectures on mathematics and was elected fellow the following March. In April 1747 he received Deacon's orders and became the curate for his uncle Charles in Swarraton. In due time he was ordained priest by the bishop of Hereford. He was elected proctor and returned to Oxford for a year in 1753. He returned to Selborn in 1755, although he did not remain there permanently until he became curate in 1784. He remained in Selborne for the rest of his life.

White is most famous for his book, The Natural History and Antiquities of Selborne, first published in 1789. The book is a compilation of a series of letters that White wrote to Thomas Pennant, a leading zoologist of the day and Daines Barrington a barrister and member of the Royal Society. In the letters, White describes his observations of nature, among other things describing the feeding habits of bats, the evening maneuvers of rooks and the improvement of horticultural soil by earthworms. In the work White identifies many species for the first time.

White is honored as the first English ecologist and the book, which has been in publication since its first printing, has been recognized as the fourth most published book in the English language, after the Bible, the Works of Shakespeare, and Bunyan's Pilgrim's Progress. White lived out his days in Selborne, passing away on June 26, 1793.

References:

Parkins, Keith;"Gilbert White"

Mabey, Richard; Gilbert White:A Biography of the Author of the Natural History of Selborne; University of Virginia Press; 2007

Gilbert White of Selborne; 1899

Gilbert White Wikipedia Entry

Theodore Maiman

Theodore Harold Maiman was born or July 11, 1927 in Los Angeles, California. The next year he moved to Denver, Colorado with his parents. His father, Abraham Maiman, was an electrical engineer and an inventor. Maiman was curious to how things work and was always taking things apart, to the dismay of his parents. In high school he worked in a electronics repair shop to earn money.

He earned a BS in engineering physics from the University of Colorado in 1949 and then went on to Stanford University where he earned a MS in electrical engineering in 1951 and a Ph.D. in physics in 1955 completing a thesis, under Willis Lamb, involving detailed optical measurements of the fine structure splittings in excited helium atoms

He then joined Hughes Laboratories where he worked on the stimulated emission of microwave energy. A MASER (microwave amplification by stimulated emission of radiation) had been invented earlier by Charles Townes working at Bell Laboratories. Townes and Arthur Schawlow in their paper suggest that their success, creating the MASER, could be repeated making a device that emits a coherent beam of light in the visual spectrum. This is called a LASER (light amplification by stimulated emission of radiation).

Maiman was the first to produce a working LASER, announcing his invention at a press conference on July 7, 1960. He published his results in the British journal Nature, after his paper was refused by Physical Review Letters because it was deemed to be to repetitive. Maiman left Hughes Laboratories in 1962 and went on to work for a series of different companies, some of his own founding, working on LASERs and their applications.

Maiman was twice nominated for the Nobel Prize and was a member of the National Academy of Science and National Academy of Engineering. He won the Oliver E Buckley Prize in 1966 and won the 1983/4 Wolf Prize for Physics. He was inducted into the Inventors Hall of Fame in also in 1984.

He died on May 5, 2007.

References:

Day, Lance; McNeil Ian; "Maiman, Theodore Harold" in Biographical Dictionary of the History of Technology; Taylor & Francis; 1998

Martin Douglas; "Theodore Maiman Dies, 79; Demonstrated First Laser";New York Times; May 11, 2007

Wycoff, Edwin Britt; Laser Man: Theodore Maiman and His Brilliant Invention; Enslow Publishers Inc; 2007

Theodore Maiman Wikipedia Entry