“The proofs obtained in these experiments—which we propose to continue—are not yet so distinct that we can measure the wave length with any precision. But we are still led to believe that this wave length is greater than that of the luminous rays.—_Comptes Rendus._” Of course, if diffraction phenomena can be demonstrated, the question as to the radiations being wave propagations, is settled, though the question whether the vibrations are longitudinal or transverse, is still open. Before accepting any stream or vortex motion theory, we need to know more about the X-ray phenomena, and more about stream and vortex motion. ------------------------------------------------------------------------ ● Transcriber’s Notes: ○ Since this is a collection of articles by different scientists, there may be differences in spelling and usage. ○ There is no experiment 64. There last experiment on page 51 is number 63_b_, and the first experiment page 52 is 65. (A note attached to the 63_b_ table of contents entry says that there is no experiment 64.) ○ The missing entries in the Table of Contents for experiments 128_a_ and 149_a_ were added. ○ There are two experiments labeled 61_b_, page 46 (Thomson’s Experiment) and 47 (Perrin’s Experiment). The instance on page 47 was relabeled 61_c_. ○ There are two experiments numbered 159 in the Table of Contents. The first follows entry 110_a_ and the other is in order, after experiment 158. The first instance was changed to 159a. ○ Missing or obscured punctuation was silently corrected. ○ Typographical errors were silently corrected. ○ Inconsistent spelling and hyphenation were made consistent only when a predominant form was found in this book. ○ Text that was in italics is enclosed by underscores (_italics_); text that was bold by “equal” signs (=bold=). ○ The use of a caret (^) before a letter, or letters, shows that the following letter or letters was intended to be a superscript, as in S^t Bartholomew or 10^{th} Century. ○ Superscripts are used to indicate numbers raised to a power. In this plain text document, they are represented by characters like this: “P^3” or “10^{18}”, _i.e._ P cubed or 10 to the 18th power. ○ Variables in formulæ sometimes use subscripts, which look like this: “A_{0}”. This would be read “A sub 0”. End of the Project Gutenberg EBook of Roentgen Rays and Phenomena of the Anode and Cathode., by Edward P. Thompson