10 ...............   1645                  501.39

These figures show that this lake exceeds in depth the deepest of the Swiss lakes (the Lake of Geneva), which has a maximum depth of 334 meters.  On the Italian side of the Alps, however, Lakes Maggiore and Como are said to have depths respectively of 796.43 and 586.73 meters.  These two lakes are so little elevated above the sea that their bottoms are depressed 587 and 374 meters below the level of the Mediterranean.

(2.) Relation of Temperature to Depth.  By means of a self-registering thermometer (Six’s) secured to the sounding-line, a great number of observations were made on the temperature of the water of the Lake at various depths and in different portions of the same.  These experiments were executed between the 11th and 18th of August, 1873.  The same general results were obtained in all parts of the Lake.  The following table contains the abstract of the average results, after correcting the thermometric indications by comparison with a standard thermometer: 

Obs. in Feet in Meters F. deg. in C._

1 ......      0-Surface            0-Surface        67           19.44

2 ......     50                     15.24           63           17.22

3 ......    100                     30.48           55           12.78

4 ......    150                     45.72           50           10.00

5 ......    200                     60.96           48            8.89

6 ......    250                     76.20           47            8.33

7 ......    300                     91.44           46            7.78

8 ......    330 (Bottom)           100.58           45.5          7.50

9 ......    400                    121.92           45            7.22

10 ......    480 (Bottom)           146.30           44.5          6.94

11 ......    500                    152.40           44            6.67

12 ......    600                    182.88           43            6.11

13 ......    772 (Bottom)           235.30           41            5.00

14 ......   1506 (Bottom)           459.02           39.2          4.00

It will be seen from the foregoing numbers that the temperature of the water decreases with increasing depth to about 700 or 800 feet (213 or 244 meters), and below this depth it remains sensibly the same down to 1506 feet (459 meters).  This constant temperature which prevails at all depths below say 250 meters is about 4 degrees Cent. (39.2 Fah.).  This is precisely what might have been expected; for it is a well established physical property of fresh water, that it attains its maximum density at the above-indicated temperature.  In other words, a mass of fresh water at the temperature of 4 deg.  Cent. has a greater weight under a