Anthony's photographic bulletin for .. . ess-board slide, such asis used in the plate-holders supplied byour publishers. Heproved, by an ex-posure of two hoursto a naked arc light,that this slide wasopaque to light fur-nished from the lat-ter source, which, asis well known, is very rich in violet and ultra-violet light. ProfessorRood rapidly arranged his apparatus and took one of these shadow-graphs by the aid of the X rayswhile we waited. The negativewas developed by us, and the re-production of it accompanies thepresent article. The object ofthe experiment, and it must beconfessed that many
Anthony's photographic bulletin for .. . ess-board slide, such asis used in the plate-holders supplied byour publishers. Heproved, by an ex-posure of two hoursto a naked arc light,that this slide wasopaque to light fur-nished from the lat-ter source, which, asis well known, is very rich in violet and ultra-violet light. ProfessorRood rapidly arranged his apparatus and took one of these shadow-graphs by the aid of the X rayswhile we waited. The negativewas developed by us, and the re-production of it accompanies thepresent article. The object ofthe experiment, and it must beconfessed that many of the ex-periments that are being madethroughout the world seem tobe without object, was to illus-trate the relative transparencyof the various substances to theseX rays. First, we would remarkthat Professor Roods apparatusis extremely simple and doesnot include anything that could not be easily arranged in any house-hold where an electric current is obtainable. Further, there was na Effect Obtained with Sunlight through Ebonite possibility for the results to be traceable to the violet light, or toany visible light, and the only visible sign of excitatioii was a slightlygreenish tinge in the tube. The ordinary incandescent current wasreduced to seven amperes and passed through an induction coil andthrough the Crookes tube. The plate-holder was placed at one end ofthe tube, the various substances being held by means of black wax ina little paper tray against the pressboard slide. After an exposureof one hour the plate was developed, and the accompanying half-toneshows the relative transparency of the various materials used to the X
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectphotogr, bookyear1870
