Page:Popular Science Monthly Volume 79.djvu/205

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PSM V79 D205 Vacuum tube of gas phosphorescence.png

Fig. 8. Vacuum Tube used to Produce Gas Phosphorescence and Photograph of Gas Phosphorescence taken by its own Light. Rapid oscillating electrical currents are sent through the coils about the vessel.

the spectrum lines of the former have not been determined. The general color of the phosphorescence in air is greenish-yellow which suggests the observed green color or meteor trains. Third, that recently by laboratory experiments the author of the present article has determined the law of the diminishing intensity of gas phosphorescence at successive intervals of time after the phosphorescence has been formed. The results of these experiments show that if the luminous meteor train is phosphorescent gas, the long duration of its visibility, often of half an hour, is readily explained from the law of the slow decaying or dying out of the luminosity shown by experiments on phosphorescent gases. This evidence and other facts point strongly to the hypothesis that the meteor train seen at night is due to phosphorescence of gas in the meteor's track.

How the Meteor Trains may be Formed

In the great Leonid meteor shower of November, 1866, and the showers following in the years 1867–68, it was noted at several observatories that the persistent luminous trains of meteors were not formed