54 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ing undulation is produced. Some of the larger seiches are 

 attributed to earthquakes. The amplitude of the vibration 

 varies in different seiches, and also in the same seiche from 

 one part of the lake to another. The duration of a seiche is 

 longer at Geneva than at Morges. 12 A, 1873, IX., 374. 



THE FLUCTUATIONS OF THE LEVELS OF THE AMERICAN LAKES. 



Dr. Dawson, geologist of the British North American 

 Boundary Commission, has published a most remarkable com- 

 parison between the fluctuations in the heights of water in 

 the American lakes and the frequency of the solar spots. He 

 states that, having;* tabulated the better known fluctuations 

 of the great lakes for a series of years, he found that these, 

 when plotted out to scale, showed a series of well-marked un- 

 dulations corresponding closely to the eleven-year period of 

 sun-spot maxima. The first four maxima of sun spots (those 

 previous to 1830), being separated by long intervals of years, 

 with few spots, appear to have been closely followed by fluc- 

 tuations in Lake Erie. The maximum of 1837, which was the 

 year of greatest known intensity of the solar phenomena, was 

 very marked in its effects on the lakes, giving rise, in 1838, 

 to the highest recorded level of the waters in Erie, Ontario, 

 and probably also in Superior. The last three periods of 

 sun-spot maxima (those of 1848, 1859, and 1869) are so short, 

 and the maxima so undecided, that the lakes appear to have 

 been unable to follow them as closely as before. One period 

 of high water is, to a considerable extent, merged in the next, 

 resulting in a general high state of the lakes for the last 

 thirty years; and, in fact, the fluctuations of the lakes seem 

 to have been especially marked when the fluctuations of solar 

 spots were also well marked. In passing from the chain of 

 great lakes to the Lake of the Woods, Dr. Dawson finds that, 

 although the data are slight, yet, at least in three cases, its 

 fluctuations appear to have coincided with those of the great 

 lakes. In explaining this remarkable connection, Dr. Dawson 

 says that the great lakes, in their changes of mean yearly 

 level, probably show a very correct average of the rain-fall 

 and evaporation over a large area, thus indicating the rela- 

 tive amount of evaporation taking place in different seasons; 

 and it is much to be desired that systematic observations 

 should be made of the actual mean annual outflow. 



