206 |Wisconsin Academy of Sciences, Arts, and Letters. 
how the upper 10 m.—15 m. of Millstatter See come to be warmer 
than those of Traun-See; for in this respect Millstatter See 
agrees with Atter-See, whose long axis, it may he remarked, ex¬ 
tends from north to south. We should like rather to know how* 
the deeper strata of Gmundener See are able to gain such an ex¬ 
ceptionally large amount of heat and how its water accumulates 
a total quantity of heat so much in excess of that gained by 
other and neighboring lakes of comparable area and depth. 
Nos. 21-25.—These are illustrations of lakes from the north 
slope of the Alps. Wiirm-See and Ammer See lie close together 
in the neighborhood of Munich and (are in the relatively low foot 
hills. Atter-See and Traun- or Gmundener See lie further east 
in [Austria and are in mountain valleys, though their surface 
is not so high above the sea as that of the first two named. Their 
mean depth)is also much greater. These lakes have heat bud¬ 
gets entirely comparable both in amount and variation with those 
of the group of Swiss Takes which lies on the other side of the 
Alps. 
I have included Ammer > See whose dimensions are somewhat 
less than those of Wiirm-See in order to show how nearly iden¬ 
tical in these lakes was the summer heat-income in 1881, the 
only year when we can compare them. Geistbeck (’85 p. 30) 
places Wiirm-See among the cold lakes and Ammer See among 
the warm, but the mean temperatures taken on successive days 
on [the two lakes agree within 5% and that of Ammer See is 
the lower. I have no doubt that further observations will show 
the same general result since Ammer See has a smaller mean 
depth than Wiirm-See. 
Nos. 23, 24. Atter-See, Traun-See.—The large budgets of 
Traun-See, both annual and summer, are especially noticeable. 
Two of the three winter temperatures reported are above 4.0° 
and one is much below that temperature, making a great differ¬ 
ence in the annual heat budgets. I have, however, computed 
the wind-distributed heat in each year in which there is a late 
summer or early autumn record, relying.on Milliner’s (’99 p. 3) 
statement that the water of all these lakes goes annually below 
4.0°. I have made a similar computation for the neighboring 
Atter-See. The eleven records for Traun-See are both high and 
uniform. Traun-See indeed has a much greater amount of wind- 
distributed heat than any other central European temperate 
lake which is recorded. A comparison of the records of)Atter- 
