H. C. Lewis—Zodiacal Light. 445 
as bright as the Via Lactea and at other times is fainter than 
the gegenschein. When the moon is in the sky it becomes ex- 
ceedingly bright and wide, far surpassing the Via Lactea. 
Just before the time of the rising of the moon it widens out on 
both the east and west horizons. Stars are readily seen 
through the horizon light and are but slightly dimmed in lus- 
ter. The horizon light can most easily be detected by inclin- 
ing the head toward the shoulder and glancing from the zenith 
to the horizon. 
portion and the zodiacal cone, even when very bright, extends 
it is difficult if not impossible at times to separate one from the 
other 
er. 
Conclusion.—Other observers have contributed much of im- 
portance concerning the phenomena of the zodiacal light, and 
several theories of its origin have been propose o theo 
is advanced in the present paper, and, as the observations are 
being continued, these partial results alone nave peter as a 
contribution to the store of facts already collected on this inter- 
esting phenomenon. 
Germantown, Pa., August, 1880, 
