File:The fireside university of modern invention, discovery, industry and art for home circle study and entertainment (1902) (14592269140).jpg

Identifier: firesideuniversi01mcgo (find matches)
Title: The fireside university of modern invention, discovery, industry and art for home circle study and entertainment
Year: 1902 (1900s)
Authors: McGovern, John. (from old catalog)
Subjects: Science
Publisher: Chicago, Union pub. house
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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as in a dark room, and had covered the tubewith a shield of black cardboard, through which not even the raysof the electric arc light would pass. At a point some few feet dis-tant,there lay a piece of barium platino-cyanide paper (sensitivepaper). As the light of the electric discharge played in thecovered tube he happened to notice a black line or shadowmoving on the sensitive paper. If the light came from out-doors it must be shut out; if the room were really dark, wheredid the light escape from the tube? Investigation proved thatno light was coming either from the outside or from the tubethrough the cardboard. In a short time, Dr. Roentgen hadlearned that rays were flowing through the black cardboard—rays that would go through a book or a wall as well. 93 94 THE FIRESIDE UNIVERSITY. When did the world hear of it? At the December, 1895, meeting of the Wurzburg Physio-Medical Society,Dr. Roentgen made a full report. The newscame to London by telegraph from Vienna, that the Wurzburg
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Fig. 41. DR. WILHELM KONRAD ROENTGEN. Professor had found a new kind of light. This was followedby mail advices, giving the discoverers clear and remarkablereport, and it is not unlikely that within four weeks the peopleof every civilized country in the world were experimenting withthe X Ray, taking photographs of the bones of the humanhand, and discovering the metallic contents of a pocket-bookwithout opening it. THE X RAY. 95 Tell me something of the earlier history of the X Ray. The X Ray was not possible without long-continued study ofthe subject of Fluorescence or Phosphorescence, Radiance andInduction, as we will here try to show you. In 1852, ProfessorStokes inserted a buirs eye of blue (cobalt) glass in the wall ofa dark room. Through this bulls eye a ray from the sun wasadmitted, making a feeble violet colored light. In front of thebulls eye he held a piece of canary glass (glass colored yel-owish green with oxide of uranium). This canary glass lit upbrilliantly in the feeble

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