1000 Wisconsin Academy of Sciences, Arts, and Letters . 
viscosity increases by less than 20%, or less than 1-50 as much. 
Thus it appears that the decline of the thermal resistance is 
far more rapid in water than is the increase of viscosity, and 
the increased ratio of decline as the temperature nears 4° is 
much greater than the ratio of increase of viscosity. 
It is impossible to say how much must be added to the num¬ 
bers in column V if it is desired to express by them not only 
the work done against gravity but also that against viscosity 
in mixing a unit column of water in a unit of time. But it 
is clear that the addition, whatever it may be, cannot be more 
than doubled between 30° and 4°. 
This is not the place for a complete discussion of the various 
factors aiding or opposing the distribution of the surface water 
through the lake, but it may be pointed out that since the in¬ 
fluence of the wind will vary as the square of its velocity, the 
greater amount of wind in the spring will more than compen¬ 
sate for any increase in viscosity. The average velocity of the 
wind in Madison in July is about 8.3 miles per hour and in 
April 11.6 miles. The ratio of the squares of these numbers is 
about as 1 to 2, showing that the mixing power of the wind in 
April is about twice as great as in midsummer. 
Literature Cited. 
Groll, ? 05: Der Oeschinensee. Max Groll. Jahresber. der 
Geog. Gesellschaft von Bern, xix: pp. 1-78; 7 figs.; 2 
maps. 
Richter, ? 07: Seestudien. E. Richter. Geog. Abhld . heraus - 
gegeben vqn Prof. A. Penck in Wien., vi, H. 2: pp. 1-72; 
pi. I-II. Wien, 1897. 
Ule, ? 01: Der Wurmsee (Starnbergersee) in Oberbayern. 
Eine Limnologische Studie. Willi Ule. Wissenschaft. 
Verojfentlich. des Vereins fur Erdkunde zu Leipzig , 
v: pp. i-vi, ( T-212; pi. 5; figs. 15 and atlas of 8 plates. 
Leipzig, 1901. 
Wedderburn, ? 09: Temperature Observations in Loch Garry 
(Invernessshire). With Rotes on Currents and Seiches^ 
E. M. Wedderburn. Proc. Roy. Soc. Edinburgh, xxxix, 
pt. ii: pp. 98-128; figs. 1-6. Edinburgh, 1909. 
