Surface currents of Lake Michigan, 1931 and 1932

Seven hundred fourty-five bottles containing post cards for recording of information were released at stations in Lake Michigan; 283 were released June 17 to August 17, 1931, south of a line from Frankfort, Michigan, to Algoma, Wisconsin, and 462 during May 9 to August 25, 1932, both south and north of that line. One hundred eighty-six bottles or 65.7 percent of those released in 1931, 331 bottles or 71.6 percent of 1932 releases, and 517 bottles or 69.4 percent of releases in the 2 years were recovered. Recoveries of bottles from both years indicated that the surface currents were somewhat variable, but their general direction was from west to east and predominately northeast in 1931 and northeast and southeast in 1932.