Page:Popular Science Monthly Volume 59.djvu/43

Rh nor conld we at any time perceive an odor, both of which have been reported in connection with the northern lights.

A phenomenon which displays its glories in skies so remote and under conditions so mysterious cannot fail to excite popular interest. This interest generally suggests the question, 'What is the aurora?' This was the inquiry of ancient, as it is still the query of modern students, and our answer is the repetition of the old question, 'What is it?' We are still far from a solution of the problem. We have, however, advanced far enough to put aside many old theories, and we hope that we are now on the train of inquiries which will eventually solve the mystery.

The similarity of auroral light to that generated in a vacuum bulb by the passage of electricity, it is now believed, lends support to the proposition, suggested long ago, that the aurora is of electrical origin. It was expected that that great mystery-solver, the spectroscope, would help us in this matter, but it has only served to add further mystery to the subject. For the line which it sifts from the aurora is not matched by any other known substance. A similar line is found in the zodiac light, but this does not elucidate the matter. The zodiac light, though better studied, is still as mysterious as the aurora. When electricity passes through rarefied air it exhibits a luminous stream which seems to have the characteristics of the aurora, hence it is quite probable that this natural phenomenon is the result of currents of electricity passing through the upper regions of the atmosphere, particularly by an exchange of celestial and terrestrial electricity.

The question is, however, one of the problems of the future. Though many exploring expeditions have penetrated the icy polar solitudes, very few men have given the time and patience necessary for a systematic study of the aurora. No travelers should enter the realms of the polar lights without being prepared to record, with the accuracy required by science, the plays of this heavenly mystery. I believe that, when men shall have penetrated a little farther southward into the unexplored area about the south pole, the aurora australis will be found just as brilliant, as varied and as frequent as the aurora borealis. With our present marvelous strides in uncovering the accumulating mysteries of past centuries, we ought, ere long, to look with pride and understanding into the dark vault of the polar night and read the flaming letters which must there reveal a thrilling tale of Nature's most cherished secrets.