498 JOURNAL OF SCIENCE. 
independent of these causes, and which resemble tides in their rythmic 
periods. These have long been known and observed in Switzerland, and 
especially on the Lake of Geneva, where they are known by the name 
of “seiches.” When they affect the lake its level is observed to rise 
slowly during 30 or 40 minutes to a height that varies from a few 
inches to as many feet; then it falls again slowly to a corresponding 
depth, and so on. These seiches have been studied for many years, and 
M. Vaucher said that he had observed that ‘‘when the barometer was: 
at rest the seiches were small, are greater when the barometer is 
variable, and greatest when the pressure is falling.” A seich is defined 
as a complete motion of the water in rising and falling, and its ‘‘period” 
as the time it takes to complete the motion. Their amplitude is very 
variable, but at the same place and on the same day they are all alike, 
when large all are large, and when small all are small. Sometimes, as 
on August 3, 1763, they have been measured 4 feet 10 inches rise and 
fall; and on 2nd and 3rd October, 1841, some were measured 6 feet 7 
inches. They are greater at the ends of the lake than in the middle, 
and the period varies very much with, the size of the lake; but in the 
Lake of Geneva, which is 45 miles long and 8 wide, the longer ones 
have a period of 72 minutes, and the shorter ones of 35 minutes. Dr. 
Forel, who has ‘studied those of the Lake of Geneva very carefully, 
attributes the ordinary seiches to local variations of atmospheric 
pressure giving an impulse the effect of which lasts a long time in the 
oscillations of the lake; but those of from 4 to 5 feet he attributed at 
one time to earthquake shocks, but now thinks they are due to violent 
gusts of wind, for at least one earthquake passed the lake without pro- 
ducing such motions. M. Plantamour, who was watching at the end 
of the lake, while Dr. Forel was in the middle, said after long and care- 
ful study he was quite at a loss for an explanation of these curious 
motions. Some of the surroundings of Lake George are of very great 
interest, viewed in the light of discussions as to the possible change in 
the amount of rainfall in the colony during long periods, and although I 
cannot now stay to discuss them at length, I cannot pass them without 
a short reference to their bearing on the question. The lake itself is 
situated in a depression between two ranges of hills, some of which, on 
the western side, rise to 1500 feet above the lake. On the eastern side 
the hills generally stand some little distance from the water, but on the 
western side, at least in a part of it, the hills seem to rise abruptly out 
of the water at an angle of from 30° to 45°. The hills are composed of 
hard metamorphic rocks, the fragments of which are carried down into 
the lake by every shower, and are very soon polished into gravel by the 
action of the waves, and the enormous deposits of gravel at both ends of 
the lake, where the ground is flat, as well as along the sides, point to a— 
duration of present conditions which is very hard to realize. At the 
present time there is a gravel ridge a short distance from the water at 
the south end. It is a mile and a quarter long, has been tested for 
ballast for the railway, and found to be at least 15 feet thick where 
deepest, and has a base of about 100 yards. This is one of a number of 
such deposits at the south end of the lake. At the railway works, 
Bungendore (south end), a well was sunk for water about 14 miles from 
the lake, in ground the surface of which would, I should think, be about 
20 feet above the present level. There was 4 feet of earth on top; then 
clean gravel to 28 feet deep. There the abundance of water stopped 
