The cover image was created by the transcriber and is placed in the public domain.
In addition to the illustrated feature for exhibiting the natureand practical application of X-rays, and for simplifying the descriptions,the book involves the disclosure of the facts and principlesrelating to the phenomena occurring between and around chargedelectrodes, separated by different gaseous media at various pressures.The specific aim is the treatment of the radiant energydeveloped within and from a discharge tube, the only source ofX-rays.
Having always admired the plan adopted by German investigatorsin publishing accounts of their experiments by means ofnumbered paragraphs containing cross-references and sketches, theauthor has likewise treated the investigations of a large numberof physicists. The cross-references are indicated by the sectionsign (§). By reference, the analogy, contrast, or suggestiveness maybe meditated upon. All knowledge of mod