1875-1900

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 * __1895-Wilhelm C Roentgen__**- He was born on //March 27, 1845//at Lennep in the Lower Rhine Province of Germany. In 1895 He discovered and described the physical properties of X-rays. Wilhelm C Roentgen was an only child of a merchant in, and manufacturer of, cloth. He showed a love of nature and was fond of roaming in the open country and forests. He was especially apt at making mechanical contrivances, a characteristic which remained with him also in later life. He then entered the University of Utrecht in 1865 to study physics, and became a mechanical engineering student. Rontgen's first work was published in 1870, dealing with the specific heats of gases, followed a few years later by a paper on the thermal conductivity of crystals. Among other problems he studied were the electrical and other characteristics of quartz. In 1895 Roentgen discovered that electrons could pass though low pressure gas, and from there figured how to take an X-ray of a person and demonstrated on his wife’s hand.



--** Henri Becquerel ** Antoine Henri Becquerel was born in Paris on December 15, 1852. Becquerel made his discovery in the year 1896. He was in a family of distinguished scholars and scientists. His father was a professor of applied physics and had done research on solar radiation and phosphorescence. Becquerel entered the Polytechnic in 1872, then the government department of Ponts-et-Chaussées in 1874, becoming ingénieur in 1877 and being promoted to ingénieur-en-chef in 1894. In 1888 he acquired the degree of docteur-ès-sciences. From 1878 he had held an appointment as an Assistant at the Museum of Natural History, taking over from his father in the Chair of Applied Physics at the Conservatoire des Arts et Metiers. In 1892 he was appointed Professor of Applied Physics in the Department of Natural History at the Paris Museum. He became a Professor at the Polytechnic in 1895. He discovery that Becquerel made was of the phenomenon of natural radioactivity. This discovery was made accidentally in 1896. When Becquerel got word that Röntgen had discovered that X-rays excite fluorescence in some substances, he was attempting to see if phosphorescent substances emitted rays also. He wrapped a photographic plate in black paper and exposed it to sunlight, when he did this fogging had occurred. He then tried this in the dark and got the same results, proving that uranium is radioactive. This experiment showed that the electrons departing the nucleus of an atom are at a high speed. http://nobelprize.org/nobel_prizes/physics/laureates/1903/becquerel-bio.html http://www.daviddarling.info/encyclopedia/B/Becquerel_Henri.html

--** Joseph John Thomson ** Joseph John Thomson was born in Cheetham Hill, a suburb of Manchester on December 18, 1856. Thomson made his discovery in 1897. He went to Owens College, Manchester, in 1870m and in 1876 entered Trinity College in Cambridge as a minor scholar. He remained a member of the college for the rest of his life, as a Lecturer in 1883, and Master in 1918. Also Thomson had become a professor of Experimental Physics at Cambridge in 1918, and an Honorary Professor of Physics. The discovery Joseph John Thomson made on the atomic structure was emulated in his //Treatise on the Motion of Vortex Rings.// This won him the Adams prize in 1884. He had gone on to suggest that the atom was a small sphere, suggesting that it is not invisible. He also discovered the election. This notion came from the cathode ray tube. Thomson found that the glowing material would bend toward a positively charged electric plate. These particles were named electrons. This helped change the look of the atom to his Plum Pudding Model. [] []