152 
Philippine Journal of Science 
1920 
20° and south 40° always set in a sea horizon. The low situa- 
tion of the city, formerly swamp land near the level of Manila 
Bay, subjects it to a maximum of atmospheric absorption; the 
factory and power-plant chimneys along Pasig River and the 
steamers in the harbor send out vast volumes of sooty smoke; 
during the dry season dust often fills the air; and a very good 
electric street-lighting system brightly illuminates smoke, dust, 
and low clouds overhead; so that opportunities for satisfactory 
observation of the delicate pale dawn, the Zodiacal Light, or 
the Gegenschein are none, and evening observations of twilight 
are usually worthless. 
Nevertheless, being in the University of the Philippines at 
Manila, and finding that early rising in the balmy morning air 
is not the sad discomfort of 4 o’clock in New England, and 
finding also that the complete series of dawn phenomena is over 
in a fraction of the time it takes in latitude 42°, I have made 
observations during a year’s clear weather on low-sun phenomena 
at Manila, hoping that even such amateur work may prove of 
some use in adding to our knowledge of the earth’s atmosphere. 
The “darkness of night” is of course only a relative term. 
The night is sometimes “as dark as a pocket” when the sky 
is overcast with rainy storm clouds; yet an overcast sky, in 
which no stars are visible and during the “dark of the moon,” 
sometimes is bright enough for comfortable walking along a 
country road. The solely starlit sky, in clear weather, is far 
from dark; on the Benguet plateau, in April, 1919, I have been 
able to read the seconds dial of my watch, with the help of a 
pocket lens, by the light of the Galaxy and the stars from 
Scorpio to Cygnus. The total light of starlit hemisphere is 
quoted by Kimball ^ as somewhat in excess of that of a thou- 
sand stars of the first magnitude, or one two-hundred-and- 
fiftieth of the brightness of the full moon. Of course, this 
brightness is not evenly distributed, the Galaxy emitting a dis- 
proportionate amount, and atmospheric absorption cutting off 
much light of stars at low altitudes. 
This starlit sky is not, however, always of the same dimness 
between the stars; there are times when it is distinctly pale.^ 
This is not attributed to any terrestrial cause, but is as if the 
earth at times passes through regions of space which are lu- 
' Kimball, H. H„ Mo. Weath. Rev. 44 (1916) 620. 
’ Simon Newcomb quotes Barnard’s word “milky.” Zodiacal Light, Encyc. 
Brit. 11th ed. 28 (1911) 998-1000. 
