ORIGIN OF LUMINOUS METEOR TRAINS 



201 



Fig. S. Vacuum Tube used to Produce Gas Phosphorescence and Photo- 

 graph of Gas Phosphorescence taken by its own Light. Rapid oscillating elec- 

 trical currents are sent through the coils about the vessel. 



the spectrum lines of the former have not been determined. The gen- 

 eral color of the phosphorescence in air is greenish-yellow which sug- 

 gests the observed green color or meteor trains. Third, that recently 

 by laboratory experiments the author of the present article has de- 

 termined 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 phosphores- 

 cence 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 observ- 

 atories that the persistent luminous trains of meteors were not formed 



VOL. LXXIX. — 14. 



