PREFACE 
This report is the result of the dynamic oceanographic work in- 
augurated in the year 1933 by the U.S.S. Hannibal in Pacific Panaman 
and Costa Rican waters. Commanders C. C. Slayton and R. M. 
Hinckley, United States Navy, were in command of the U.S.S. 
Hanmibal. 
The leading oceanographical institutions of this country, including 
the Scripps Institution of Oceanography; the Woods Hole Oceano- 
eraphic Institution; and the Carnegie Institution of Washington, 
D.C., greatly aided the Hydrographic Office in making possible the 
inauguration of the dynamic oceanographic surveys by their advice 
relating to methods, the loan of equipment, and their encouragement. 
Mr. R. H. Fleming of the Scripps Institution of Oceanography, 
University of California, La Jolla, Calif., Dr. T. Wayland Vaughan, 
director, was granted permission by the United States Navy Depart- 
ment to accompany the U.S.S. Hannibal and greatly assisted in 
making observations necessary for the dynamical study of the waters 
traversed, and in addition made observations on the dissolved oxygen, 
phosphate, silicate, nitrite and other chemicals, and plankton. The 
values of the samples of water collected were determined and checked 
at the Scripps Institution of Oceanography for temperature, chlorinity, 
salinity, specific gravity, and other quantitative hydrodynamic data. 
There are also included in this report the dynamic oceanographic 
data collected by the yacht Velero JJZ, G. Allan Hancock, captain 
and owner, and surface temperature and salinity data collected by 
United States naval vessels. These data were also checked by the 
Scripps Institution of Oceanography and the resulting values 
determined. 
W. R. GHERARDI, 
Rear Admiral, United States Navy, Hydrographer. 
Unitep States Hyprocrapuic OFFice, 
August 1934. 
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