| [41.] | Discharge Tube in Primary Current. Striæ. Least E. M. F. Required. | Gassiot |
| [42.] | Current Interrupted Inside of Discharge Tube instead of Outside. | Poggendorff |
| [43.] | Source of Striæ at the Anode. Color Changed by Change of Current. | De La Rue and Müller |
| [44.] | Dark Bands by Small Discharges Disappear on Increase of Current, and Appear Again by Further Increase. | Solomons |
| [45.] | Motion of Striæ. Method of Obtaining Motion when Desired and of Stopping the Same. | Spottiswoode |
| [46.] | Motion of Striæ Checked at the Cathode. Tube, 50 ft. Long. The Anode the Starting-point. | Thomson, J. J. |
| [47.] | Electrolysis in Discharge Tube. | Thomson, J. J. |
| [48.] | Heat Striæ without Luminous Striæ. | De La Rue and Müller |
| [49.] | Sensitive State. Method of Obtaining. Telephone Used to Prove Intermissions. | Spottiswoode and Moulton |
| [49a.] | Cause of Sensitive State Detected by Telephone. | Spottiswoode and Moulton |
| [50.] | Sensitive State Illustrated by a Flexible Conductor within the Discharge Tube. | Reitlinger and Urbanitzky |
| [51.] | System of Operating Discharge Tubes. Excessively High Potential and Enormous Frequency. | Tesla |
| [52.] | Discharge-tube Phenomena by Self-induced Currents. | Moore |
CHAPTER V.
| [53.] | Dark Space around the Cathode. | Crookes |
| [54.] | Relation of Vacuum to Phosphorescence. | Crookes |
| [55.] | Phosphorescence of Objects within Discharge Tube. | Crookes |
| [56.] | Darkness and Luminosity in the Arms of a V Tube. | Crookes |
| [57.] | Cathode Rays Rectilinear within the Discharge Tube. | Crookes |
| [58.] | Shadow Cast within the Discharge Tube. | Crookes |
| [58a.] | Mechanical Force of Cathode Rays. Wheel Caused to Rotate. | Crookes |
| [59.] | Action of Magnet upon Cathode Rays in Discharge Tube. | Crookes |
| [60.] | Mutual Repulsion of Cathode Rays in Discharge Tube. | Crookes |
| [61.] | Heat of Phosphorescent Spot. | Crookes |
| [61a]. | Theoretical Considerations of Thomson (Kelvin). | |
| [61b], page [46]. | Velocity of Cathode Rays. | Thomson, J. J. |
| [61b], page [47]. | Cathode Rays Charged with Negative Electricity. | Perrin |
| [61c], | Zeugen’s Photograph of Mt. Blanc Not Due to Cathode Rays. | |
| [62.] | Phosphorescence of Particular Chemicals by Cathode Rays. | Goldstein |
| [63.] | Spectrum of Post-phosphorescence of Discharge Tube Compared with that of Red-hot Metals. | Kirn |
| [63a.] | Chemical Action on Photographic Plate by Cathode Rays Inside of Discharge Tube. | De Metz |
| [63b.] | The Passage of Cathode Rays through Thin Metal Plates within the Discharge Tube (no. § 64). | Hertz |
CHAPTER VI
| [§ 65], top of page [53]. | Cathode Rays Outside of the Discharge Tube whose Exit is an Aluminum Window. A Glow Outside of the Window. | Lenard |
| [65.], end of page [53]. | Properties of Cathode Rays in Open Air. | Lenard |
| [66.] | Phosphorescence by Cathode Rays Outside of the Discharge Tube. | Lenard |
| [66a]. | Transmission Tested by Phosphorescence. | |
| [67.] | The Aluminum Window a Diffuser of Cathode Rays. | Lenard |
| [68.] | Transmission of External Cathode Rays through Aluminum and Thinly Blown Glass. | Lenard |
| [69.] | Propagation of External Cathode Rays. Turbidity of Air. | Lenard |
| [70.] | Photographic Action by External Cathode Rays and at Points beyond the Glow. No Other Chemical Power Probable. Shadows of Objects by Light and by External Cathode Rays Compared. No Heat Produced by External Cathode Rays. | Lenard |
| [71.] | External Cathode Rays and the Electric Spark Distinguished. Aluminum Window Not a Secondary Cathode. | Lenard |
| [72.] | Cathode Rays Propagated, but Not Generated, in the Highest Possible Vacuum. Air Less Turbid when Rarefied. | Lenard |
| [72a]. | Cathode Rays, while Traversing the Exhausted Observing Tube, Deflected by a Magnet. No Turbidity in a Very High Vacuum. | Lenard |
| [72b]. | An Observing Tube for Receiving the Rays and Adapted to be Exhausted. | Lenard |
| [73.] | Phenomena of Cathode Rays in an Observing Tube Containing Successively Different Gases at Different Pressures. Phosphorescent Screen Employed for Making the Test. | Lenard |
| [74.] | Cause of the Glow Outside of the Aluminum Window. Glow Not Caused by External Cathode Rays. Sparks Drawn from the Aluminum Window. Transmission of External Cathode Rays Dependent Alone upon the Density of the Medium. | Lenard |
| [75.] | External Cathode Rays of Different Kinds Variably Diffused. Theoretical Observations. | Lenard |
| [76.] | Law of Propagation of External Cathode Rays. | Lenard |
| [77.] | Charged Bodies Discharged by External Cathode Rays. Discharge at Greater Distances than Phosphorescence. Not Certain as to the Discharge Being Directly Due to Intermediate Air. | Lenard |
| [78.] | Source, Propagation, and Direction of Cathode Rays. General Conclusions. | De Kowalskie |
CHAPTER VII.
| [79.] | X-rays Uninfluenced by a Magnet. Source of X-rays Determined by Magnetic Transposition of Phosphorescent Spot. | Roentgen |
| [80.] | Source of X-rays may be at Points within the Vacuum Space. Different Materials Radiate Different Quantities of X-rays. | Roentgen |
| [81.] | Reflection of X-rays. | Roentgen |
| [82.] | Examples of Penetrating Power of X-rays. | Roentgen |
| [83.] | Permeability of Solids to X-rays Increases Much More Rapidly than the Thickness Decreases. | Roentgen |
| [84.] | X-rays Characterized. Fluorescence and Chemical Action. | Roentgen |
| [85.] | Non-refraction of X-rays Determined by Opaque and Other Prisms. Refraction, if Any, Exceedingly Slight. | Roentgen |
| [86.] | Velocity of X-rays Inferred to be the Same in All Bodies. | Roentgen |
| [87.] | Non-double Refraction Proved by Iceland Spar and Other Materials. | Roentgen and Mayer |
| [88.] | Rectilinear Propagation of X-rays Indicated by Pin-hole Camera and Sharpness of Sciagraphs. | Roentgen |
| [89.] | Interference Uncertain Because X-rays Tested were Weak. | Roentgen |
| [90.] | Electrified Bodies, whether Conductors or Insulators, or Positive or Negative, Discharged by X-rays. Hydrogen, etc., as the Intermediate Agency. | Roentgen |
| [90a.] | Application of Principle of Discharge by X-rays. | Roentgen |
| [90A,] [b,] [c,] [d.] | Supplementary Experiments on Charge and Discharge by X-rays. | Minchin, Righi, Benoist, Hurmuzescu, and Borgmann |
| [91.] | Focus Tube. | Roentgen, Shallenberger, et al. |
| [91a.] | Tribute to the Tesla Apparatus. | Roentgen |
| [92.] | X-rays and Longitudinal Vibrations. | Roentgen |
| [93.] | Longitudinal Waves in Luminiferous Ether by Electrical Means Early Predicted by | Thomson (Kelvin) |
| [94.] | Theory as to X-rays Being of a Different Order of Magnitude from those so far Known. | Schuster |
| [95.] | Longitudinal Waves Exist in a Medium Containing Charged Ions. Theoretical. | Thomson, J. J. |
| [96.] | Practical Application of X-rays Foreshadowed. | Boltzmann |
| [97.] | The Sciascope. | Magie, Salvioni, et al. |
CHAPTER VIII.
| [97a.] | Electrified Bodies Discharged by Light of a Spark, and the Establishment of a Radical Discovery. | Hertz |
| [97b]. | Above Results Confirmed and More Specific Tests. | Wiedemann and Ebert |
| [98.] | Negatively Charged Bodies Discharged by Light. Discharge from Earth’s Surface Explained by Inference and Experiment. | Elster and Geitel |
| [99.] | Relation between Light and Electricity. Cathode of Discharge Tube Acted upon by Polarized Light and Apparently Made a Conductor Because of the Discharging Effect. | Elster and Geitel |
| [99A] to [99T.] | Briefs Regarding Action between Electric Charge and Light. | Schuster, Righi, Stolstow, Branly, Borgmann, Mebius, et al. |
CHAPTER IX.