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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
seven feet deep. When the wind blew in the opposite direction, 
away from the pier, there was an upward and outward move- 
ment resulting in a lower temperature at the bottom at the end 
of the pier. During the latter part of June and the early part 
of July the water from beneath the surface mingling with that 
at the surface (combined with effects due to radiation, evapora- 
tion and contact with air of different temperature) caused a 
drop in the surface temperature of one and even two degrees, 
and on one occasion (June 21), assisted by the low temperature 
half way between the end of the spit and the laboratory pier in Miller’s Bay. 
of a cool day, caused a lower temperature at the evening ob- 
servation than at the morning observation, the temperature at 
the surface and at the bottom being the same (62.5° Fahr.), the 
latter without the immediate influence of evaporation and of 
the temperature of the air. On quiet sunny days the tempera- 
ture of the surface water rose even as much as six degrees 
(July 29). 
