INTRODUCTION 
The observations are usually made once each weekday at whatever time 
the observer attends the gage. At some stations situated within or near 
the entrance of an estuary, the temperature or density varies with the stage 
of tide or with the direction of the tidal current. It may be assumed that 
in the course of a month or more the distribution of observations is fairly 
uniform over all phases of the tide. 
The mean temperature and density curves are derived from the monthly 
means given in Table 1 and show graphically the seasonal variation for 
many places, 
For some practical uses of density data, it is more important to know 
the density at the temperature apt to be encountered than at the standard 
temperature, The graph, Sea Water Density at Various Temperatures, provides 
for converting density at 59°F (15°C) to density at other temperatures. 
The following Coast and Geodetic Survey publications on sea water tem- 
peratures, salinities and densities are also available: 
C&GS Publication 31-1, Surface Water Temperature and Density, 
Atlantic Coast, North and South America (Third Edition) 
1968, $1.00. 
C&GS Special Publication No, 298, Sea Water Temperature and 
Density Reduction Tables, 1953, 25 cents, 
