610 The Philippine Journal of Science 1920 
spent in observing low-sun phenomena at San Fernando Point 
Lighthouse, La Union, and at Baguio. For sunset observing, 
with the hope of making approximate determinations of atmos- 
pheric refraction at both lower and upper contacts and at stations 
from sea level to an elevation of more than 2 kilometers, the 
apparatus taken consisted of a watch with a high-grade Elgin 
movement, a i second stopwatch (works marked Mont Brillant 
W. Fy. Switzerland), a 10-power galvanometer telescope with a 
light camera tripod, aneroid barometer, thermometer, sling psy- 
chrometer, etc. The stopwatch had been carefully rated, as had 
been done with the other one mentioned above; its rate correc- 
tion was — 1.1 sec./min., its flyback correction +0.1 second, both 
constant. This watch was used for Nos. 37 and 42; it balked in 
the middle of No. 38, and the other sunsets at San Fernando 
Point Lighthouse, Nos. 39 to 41, were timed with a National 
Park stopwatch, which the keeper in charge, Mr. Fernando Quin- 
tos, kindly allowed me to use. Its correction was found to be 
+ 0.06 sec./min., constant. I had hoped to use an engineer’s Y- 
level for this work, with a chronometer, but the nonarrival of 
the chronometer made the Y-level superfluously accurate. 
No. 37 was observed with stopwatch and field glass ; Nos. 39 to 
42 with 10-power galvanometer telescope on tripod, stopwatch, 
and watch, thus; at lower contact the stopwatch was started, 
then stopped at an instant known by the watch, started at another 
known instant, and stopped at upper contact. Thus not only 
the duration but also the standard time of each contact was 
determined. 
The sun sets at Manila in a water horizon between Corregidor 
Island and the promontory of Bataan Province, for a few weeks 
before and after the winter solstice; at other times of the year 
the sunset is over a land horizon. Before the solstice in 1918 I 
made no duration observations, not having any idea that they 
could be of interest; before the solstice of 1919 continued cloudi- 
ness made observations at Manila impossible up to December 9, 
1919. I was absent from the city during the Christmas recess, 
when I had hoped to make observations on the duration of sun- 
rise from points on the Pacific shores of Luzon, but again 
cloudiness prevented. 
Nos. 1 to 12 were made on the sea wall along the Cavite Boule- 
vard, Manila, at a point in latitude north 14° 34.4', longitude 
east 8 h. 3 m. 55.2 s., by the City Map of the Bureau of Com- 
merce and Industry; Nos. 18 to 36 were made on the sea wall a 
little farther south, latitude north 14° 34.3', longitude east 8 h. 
