ZODIACAL LIGHT. 105 



auroral streamers which wave across the skies of one country must 

 move synchronously with those which are visible in the skies of 

 another country, even though thousands of miles may separate the 

 two regions. 



" Could we only associate auroras with terrestrial magnetism, we 

 should still have done much to enhance the interest which the beau- 

 tiful phenomena are calculated to excite. But when once this asso- 

 ciation has been estabhshed, others of even greater interest are 

 brought into recognition ; for " — I take the liberty of italicizing for 

 emphasis this portion which is printed in Roman in the text — " ter- 

 restrial ftiagnetism has been clearly shown to be influenced directly 

 by the action of the sun^ 



" We already begin to see, then, that auroras are associated in 

 some mysterious way with the action of the solar rays. The phe- 

 nomena which have been looked upon for so many ages as a mere 

 spectacle, caused perhaps by some process in the upper regions of 

 the air, of a simply local character, have been brought into the 

 range of planetary phenomena. 



" Most of my readers have doubtless heard of the zodiacal 

 light, and many of them have perhaps seen that mysterious radi- 

 ance, pointing obliquely upward from the western horizon, soon 

 after sunset in the spring months, or in autumn shortly before sun- 

 rise, above the eastern horizon. The Hght, as its name indeed im- 

 plies, lies upon that region of the heavens along which the planets 

 travel. Accordingly, astronomers have associated it with the plan- 

 etary orbits, and have come to look on it as formed by the light re- 

 flected from a multitude of minute bodies travelling around the sun 

 within the orbit of our earth." After a short account of the spec- 

 troscope and its use in analyzing substances especially those reflect- 

 ing light or luminous in themselves, he says : " Recently, however, 

 zodiacal light has been analyzed by Angstrom, with a result alto- 

 gether unexpected, and at present almost unintelligible. Its spec- 

 trum exhibits a bright line, and this bright lifte is the sa?ne that is 

 seen in the spectnun of the atwora borealisP^ 



Furthermore : " Of all the phenomena presented to the contem- 



