78 



Temperature. 

 Temperature readings were marie by means of a thermophone, and 

 were taken simultaneously with the plankton catches. The temperature of 

 the surface water, during the sunnner. varied from 21° to 26° C. At the bot- 

 tom of the lake, only a slight variation ranging from 8.3° C. to 9° C. oc- 

 curred. The tlierniocline was about 6 or 7 m. in thickness. The epiliranion 

 was 5.5 m. thick on July Ist; by the niiddU' of August it had descended to 

 14.5 ni. This descent of the therniocliuc was associated with the high wind 

 and cb)udy days of the latter part of August. The average vertical readings 

 are given in tlie accompanying temperature graph. They were taken in 

 the deepest part of the lake at various times during the day. 



OUTLINE MAP OF 



WINONA LAKE 



SHOWIMG LOCATION OF STATIONS 



Weather. 



Tlic summer of lltTJ exhibited wry inisettled weather conditions in the 

 vicinity of the lake. Hti-oiig winds jirevailed much of the time, especially 



