232 
PACIFIC SCIENCE, VoL IV, July, 1950 
morning, but that the vertical gradient in- 
creases as the effect of solar radiation is felt. 
The time of maximum temperature occurs 
later at greater depths because time is re- 
quired for heat to reach these depths by 
conduction. 
The annual variation of temperature at 
subsurface depths in the area 20° to 25° N 
and 157° to 160° W is shown in Figure 27. 
The maximum temperature occurs at 400 
feet approximately 1.3 months later than at 
the surface. A secondary maximum is indi- 
cated in January. The maximum shown at 
400-foot level in April is probably not a real 
feature but one due to the uneven frequency 
distribution of observations. 
ADDITIONAL DATA AVAILABLE 
In addition to what has been published 
here, certain further investigations have been 
made and results are available from the 
Scripps Institution of Oceanography. Among 
these results are charts of the distribution of 
observations by months and hydrographic 
station data. 
REFERENCES 
Hiatt, Robert W. 1948. Preliminary note 
on the oceanographic program of the Ha- 
waiian Marine Laboratory. Pacific Science 
2 ( 1 ): 67 - 68 . 
Leipper, Dale F., and Ernest R. Ander- 
son. 1948. Sea temperature in the Ha- 
waiian Island area. Scripps Inst. Oceanog- 
raphy, Oceanographic Rpt. 12. [Mimeo- 
graphed.] 
and William Wood. 1947. Tem- 
perature and salinity of Philippine waters. 
Scripps Inst. Oceanography, Oceanographic 
Rpt. 4. [Mimeographed.] 
Spilhaus, Athelstan F. 1940. A detailed 
study of the surface layers of the ocean in 
the neighborhood of the Gulf Stream with 
the aid of rapid measuring hydrographic 
instruments. Jour. Marine Res., Sears 
Found. 3 (1): 51-75. 
Sverdrup, H. U., M. W. Johnson, and R. 
H. Fleming. 1946. The oceans, their 
physics, chemistry, and general biology. 
x + 1087 pp., 265 figs., 7 charts. Prentice- 
Hall, Inc., New York. 
TABLES 
TABLE 1 
Distribution of Bathythermograms 
by Years 
YEAR 
PERCENTAGE 
1941 
3.2 
1942 ......... 
... 2.5 
1943 
16.0 
1944 ......... 
43.0 
1945 
15.1 
1946 . . 
........ 11.7 
1947 
8.6 
TABLE 2 
Distribution of Bathythermograms 
by Months 
MONTH 
PERCENTAGE 
January 
February ....... 
March ........ 
April 
May 
9 9 
June ......... 
July ......... 
August 
........ 9.9 
September ...... 
9.2 
October 
6.4 
November ...... 
6.3 
December ...... 
4.9 
