48 CONSEKVATIOX DEPARTMENT 



torn was somewhere around 4 degrees C, any warming which may 

 have taken place during the earlier spring months having been 

 obliterated by the arrival of this ice. 



By :\Iay 25 all ice had disappeared and by the time of the 

 first' cruise which was made in the New York State Conservation 

 Department '.s launch Naveffe on June 10, 11, and 12, a pronounced 

 warming both of surface and bottom had taken place in this area. 



The first Navette cruise covered the Buffalo region and extended 

 in very shallow water along the American and Canadian shores. 

 The extreme shallowness of these shore stations gave temperatures 

 which could not be considered indicative of the lake surface as a 

 whole nor permit of comparison with the later Shearwater stations. 

 Consequently only the stations farthest out from land, lA, 2C, 

 3A, and 15C have been used for estimating the probable average 

 surface temperature in the Buffalo region. The mean of these four 

 is 13.0°. 



In the Buffalo region no noticeable vertical gradient existed, 

 but farther west there was a pronounced differential. Thus at 

 station 20 on the west side of Pt. Abino the surface temperature 

 was 15.8° while the bottom in 10.5 m. was only 10.6°. 



The second cruise took place a week later and included the 

 region along the Canadian shore from Buffalo to Port Dover. Tlic 

 mean surface temperature of the three stations occupied on the 

 first day was 13.6°. There was an even vertical gradient from toj:) 

 to bottom with no evidences of a thermocline as yet. The stations 

 in Long Point Bay near Port Dover were thoroughly mixed but at 

 the station off Bluff' Bar a temperature of only 8.8° Avas found at 

 the bottom in 14 m. 



The third Navette cruise embraced the American shore between 

 Dunkirk and Buffalo. It took place on July 11 and 12 and 

 the surface was found to have warmed to a mean temperature of 

 23.5°. This high value is due to the fact that only the marginal 

 zone of tlie lake figured in these stations and the figure does not 

 represent the mean surface temperature of the lake as a whole in 

 any sense. Vertical gradients were found to have disappeared in 

 this shallow band along the edge. 



With the arrival of tlie Shearwater at Buffalo late in July it 

 became possible to take up the original ])i"ogram which consisted 

 of occu]\vino' at weekly intervals a series of stations forming a net 

 work over tlie ai'ea to be investigated. Their location is shown 

 on the key chart. Due to certain limitations in the Shearwater's 

 equipment work could only be carried on during the daylight 

 hours and in oi-der to comiJete the cii'cuit of 23 stations thi'ee 

 (lays were f(M|uir('(l. The fii'st iiiglil was spent in Dunkirk, the 

 second in Port Doxcr, while the third day was i^issed in the return 

 to Buffalo with tlic stations that lay along this route. (\)nse- 

 (piently, stations 1 to 11 which ^^•ere taken up on \\\o fii-st day 

 between I>uffalo and Dunkii-l; were always scpai-atcd by a uap of 

 at Icjist 1 went y j'oui- hours I'l-oin slat ions 20 to 2.") which were 

 occupied on the last day's iMin. As ha|)i)ened on several occas- 



