54 Conservation Department 



Also, as the Ave.stward extension of the 50 meters level ^vas found 

 to be only about 8 miles beyond station 15, it seems prol)able that 

 the normal net movement toward the lake outlet at Buffalo was 

 concentrated solely in these upper strata, else the cold water here 

 would by now have been replaced by water from the shallower 

 parts of the lake to the west and could have been easily identified 

 by its much higher temperature. 



Yet the water in the deep hole was neither chemically nor physi- 

 cally stagnant as such a condition of apparent insulation from 

 surrounding waters might lead one to expect. Chemical analyses 

 showed an abundance of oxygen in the lower levels in spite of 

 incessant consumption by the animal members of the community, 

 although this oxygen could not have been brought there by trans- 

 ference from the aerated regions near the surface. There is 

 apparently light enough here for the plants of these waters to 

 carry on photo-synthesis. Nor is there physical stagnation here, 

 for current meters operated on the first and fourth cruises re- 

 vealed the presence of considerable velocities even in the lower- 

 most levels. More temperature data in the region lying to the 

 west of the deep hole is urgently needed if the movements of the 

 cold water are to be understood. 



The sixth and last cruise began about a week later on September 

 12 and, as it covered only the region between Buffalo and Dun- 

 kirk with the addition of station 22, a very detailed discussion 

 of temperature distribution cannot be undertaken. The surtace 

 water now had a mean temperature of 20.9° Avith approximately 

 20.6° at the ten meter level. Mixing had been so complete down 

 to 20 meters that all bottom water to the east of the Port Colbornt- 

 ' — Silver creek line was over 20°. 



The only indications w^e had of the condition of the bottom 

 water in other regions was furnished by the value 9.4° in 33 meters 

 at station 22. The water from the deep hole was apparently not 

 in movement — to the eastward at any rate. 



A Taylor self-recording thermometer was set up aboard the 

 Shearwater at her dock at the foot of Porter Avenue in order 

 to gain some idea of the magnitude of the diurnal changes taking 

 place in the surface waters. The instrument was set in such a 

 position that the capillary bulb extended about six inches below 

 the surface and on the seaward side of the vessel. The water at 

 this point was in continuous gentle movement due to a small cur- 

 rent and while exposed fully to wind action was ])rotected from 

 liigh waves by the presence of the inner breakwall a few hundred 

 yards away. Readings were taken continuously from noon of 

 September 7 to noon of September 11, and the values never rose 

 above 70°F. (21°C.) nor fell below 67°F. (19.5°C.) and this ex- 

 treme difference occurred all on the day Sejitember 7-8, the diurnal 

 changes on the other days being less than 1°F. 



Currents. — Cui'i'eiit measui-ements were taken at Station 15 — 

 the deep hole on \\h' first aiul fourth Shearwafc)' cruises. A maxi- 

 mum surface current of 0.92 ft/sec. (about 0.63 mi/lir.) Avas en- 

 countered at 8 p. m. on July 30, tlie maximum ])ottom I'cadiug of 



