instruments were clamped in a series onto a 

 cable wound on the drum of a hand-operated 

 winch. The cable passed through a meter 

 wheel that recorded the depths at which the 

 several thermometers were reversed. After 

 allowing the last attached thermometer to 

 set for about 5 minutes, a weight was re- 

 leased on the cable that reversed the first 

 thermometer and released its attached weight. 

 Each reversed thermometer, except the last 

 one, released a weight that reversed the 

 next thermometer below (see fig. 2). 



No comprehensive survey of the temper- 

 atures of Lake Michigan had been made before 

 1930. Conger (1899) discussed briefly in 

 general terms the July surface temperatures 

 obtained in 1892-94 by masters of vessels 

 plying between the lake ports. Ward (1896) 

 published bottom and surface temperatures 

 obtained August 11-25, 1894, in the north- 

 eastern part of the lake. Surface tempera- 

 tures at various Great Lakes localities were 

 kept during the period 1874-86 by the U. S. 

 Weather Bureau. They were taken daily, 

 except when the lake was frozen, at 2 p.m. 

 from docks where the water was usually 20 

 feet deep or more. The monthly means of 

 these temperatures were published by Horton 

 and Grunsky (1927) including the ports of 

 Escanaba, Milwaukee, Chicago, and Grand 

 Haven. Koelz (1929) published a few records 

 taken at the surface and bottom during 

 August 14-24 and October 11, 1920, in Green 

 Bay and off the ports of Algoma, Wisconsin, 

 and Michigan City, Indiana. Wright (1931) 

 discussed our low Lake Michigan temperatures 

 (3.8° -4.0° C.) that were taken in the sum- 

 mer of 1930 at depths beyond 100 meters. 

 He pointed out that pressure lowered the 

 temperature of the water at maximum density. 



More extensive and detailed data were 

 obtained after our 1930-32 investigation. 

 Williamson jmd Greenbsuik (1940) conducted 

 a survey of the pollution of Green Bay, the 

 lower Fox River, cind the East River during 

 the period October 1938 to June 1939 exclud- 

 ing December. Their report included a 

 series of temperatures at a number of Green 

 Bay stations where the depths varied from 3 

 to 39 feet. Records were obtained at depths 

 of 3 feet, midway to the bottom, and 1 foot 

 cibove the bottom in water more than 10 feet 

 deep but only at 3 feet in shallower water. 



Church (1942, 1945) was the first to 

 publish a comprehensive discussion of the 

 temperatures of Lake Michigan proper that 



were obtained with a bathythermograph. In 

 his 1942 paper he presented data that were 

 collected largely on a commercial ship route 

 between Milwaukee and Muskegon. Some 270 

 soundings were taken on 12 round trips on 

 this route during the period November 22, 

 1941 to March 30, 1942. In addition 71 

 soundings were made, March 28-April 6, 1942, 

 on a trip from Indiana Harbor to Charlevoix 

 via Milwaukee, Sheboygan, and Frankfort. 

 Data published in his 1945 paper covered the 

 period from March 30 to September 18, 1942. 

 Of the 759 soundings, 438 were made again 

 on the Milwaukee-Muskegon route (March 30- 

 September 13); the others were obtained at 

 a Coast Guard anchor station off Stevens- 

 ville, Michigcin (68 on September 16-18), 

 from a private yacht on the south basin 

 (39 on June 18-20), and from a commercial 

 vessel on routes between Frankfort and Msini- 

 towoc, Kewaunee, Menominee, and Manistique 

 (214 on June 7-September 10). His records 

 were not presented in detail in tabulax foim 

 but only on graphs, 



Millar (1952) reported on the tem- 

 peratures of Lcike Michigan recorded by a 

 thermograph installed on the condenser 

 intake set between 15 and 20 feet below the 

 load waterline of a steamship. Records 

 were obtained on the ship's regular route 

 between Chicago EUid the Straits of Mackinac 

 via Milwaukee. Only monthly grand average 

 temperatures were published for 17 stations 

 covering the periods from May 22 to Novem- 

 ber 13 in the years 1935 to 1939 and 

 May- July 1941. 



Great Lakes temperatures at municipal 

 water sources were compiled by the Michigan 

 Water Resources Commission (1954). The 

 Lake Michigan data were collected either in 

 1952 or 1953 at the intakes of Menominee, 

 Escanaba, Traverse City, Muskegon, Grand 

 Rapids, and St. Joseph, the depths of which 

 ranged from 12 to 60 feet. The published 

 records were monthly averages, maximum, 

 and minimum. 



Griffith (1955) published a curve 

 (no tables) of surface temperatures obtain- 

 ed at EvEinston, Illinois at the end of a 

 breakwater where the water was about 2 

 meters (6.6 ft.) deep. Observations were 

 made with a maximum-minimum thermometer 

 throughout a year from April 1953 to March 

 1954. Smith (1956) discussed in general 

 terms the position of the thermocline in 

 northern Lake Michigan but presented no 



