388 Wisconsin Academy of Sciences, Arts, and Letters. 
Plate X. Thermal resistance. Lake Mendota, Aug. 1915. The 
diagram shows the thermal resistance to mixture presented by 
lake Mendota under the temperature conditions discussed in other 
diagrams and tables. The vertical spaces represent depth: each 
horizontal space represents five units of thermal resistance as 
defined on p. 363. The length of the heavy black line shows the 
number of such units that are found in the one-meter stratum 
within which it lies. 
Note the concentration of resistance in the thermocline, and to 
a less degree at the surface. Note also that the currents directly 
caused by wind have to meet an increasing resistance at the thermo¬ 
cline with currents that are declining in energy. Below the thermo¬ 
cline the indirectly caused currents are operating on water whose 
resistance is decreasing as the depth increases. 
