82 



U. S. COAST AND GEODETIC SURVEY 



drawn from the harbor or sea, and the temperature of the water in the 

 jar in which the hydrometer is floated taken at the time of the hy- 

 drometer reading. The temperature of the sea water must be taken 

 in the bucket immediately after the water has been drawn and before 



Rev. Dec., 1930 



SicUcK iii;lfentic..C.ity (Steel Pier J, i, 



DENSITY AND TEMPERATURE 



J. 



1-. — a9.''...2i'...;j 



u„i 7i°..Zs.'..Ai 



MuM ._ -AugHsl;.. 



Y,« 1.924 



..S.«ij.«.e.J-.l>.ei.1;.cii.. 



* Not to bo rilled 



■<-«» (OVER) DmllyttJ^ti iy...CA.IjtCj>«..lifl.Tj,..2C«..lS24. 



FiGDRB 29. — Form 457, density and temperature. 



it has had time to be affected by the temperature of the surrounding 

 air. The temperature of the water in the jar, which is used to reduce 

 the hydrometer reading to a standard temperature, is not taken until 

 there has been time for the water, the jar, and the hydrometer to 

 become adjusted to a uniform temperature. Sometimes the column 

 of mercury in the thermometer may become separated in sections, 



