SECOND RECORD OF OSCILLATIONS IN LAKE LEVEL 37 
Circulation that was pronouncedly horizontal was commonly 
noticeable at the end of the laboratory pier. Sometimes it was 
seen in the slow movement of a thin surface film even an eighth 
of an inch in depth moved by gentle winds. Often when the 
wind was strong there was a general movement of the water as 
seen at the pier. Up to the last two days of the observations this 
drift seemed to follow the direction of the wind when the wind 
was northwest, southwest, south and even southeast. Apparently 
the drift to the north when the wind was southeast was dne to 
a double eddy within the bay, a second eddy forming west of 
the spit opposite the laboratory. On the last two days (July 
26 and 27) it was noticed that even with a southwest wind the 
circulation at the pier was toward the south, as if the effect of 
the strong southeast wind of July 25 still persisted. 
Fig. lb: The heavy upper line -gives the temperature of the surface water 
at the end of the laboratory pier during the session of 1916, June 18-July 26. 
The light lower line gives the temperature at the bottom (depth seven feet) 
at the end of the laboratory pier. In places the two lines coincide. 
Apparently the weeds were interfering with the circulation in 
the bay at the times of the last two observations of temperature 
(July 18 and 2.6), since the temperature at the bottom amid the 
weeds was higher than the temperature of the water above the 
weeds. 
In the last temperature observations taken out in the lake (July 
25-26) after a strong southeast wind for two days, a stratum of 
water warmer than the water above it and also warmer than the 
water below it, was found at a depth of about eight meters (26 
feet). When this was first noticed it was thought to be due to an 
error of observation, but the difference was detected in readings 
taken a mile and a half apart and on two successive days. It 
seems evident that this circulation involved horizontal sheets of 
considerable extent. The other variations seen in the curves for 
