284 A. H. Chester—Mineralogical Notes. 
The water level of the lakes for the last 20 years is shown in 
fig. 4 and fails to show, as has been claimed, any recurring 
cycle of high or low water. 
The curves of the last 10 years show a tendency to irregulari- 
ties which may be due to changes in rainfall and water-shed 
produced by the rapid destruction of the forests which 10 years 
ago covered the basin of the upper lakes. 
Observations made by the U. S. Survey have established the 
existence of small tides, which at Chicago had an amplitude of 
13 inches for the neap tide and about 3 inches for the spring 
tides. 
There is still another class of oscillations called sezches, which 
have been already observed in the Swiss Lakes and for which 
a solution in all respects satisfactory has not been offered. 
Whenever the lakes are sufficiently free from the disturbing 
action of wind to permit observations, a quite regular series of 
small waves, or pulsations can be detected, which have an in- 
erval of about 10 minutes from impulse to impulse. These pul- 
sations seem to occur almost without cessation on Lake Superior. 
Besides having tides in common with the ocean, the lakes have 
well-defined land and lake breezes; the breeze from the lakes 
landward commencing in summer at 8 or 10 o’clock A. M., and 
continuing until sunset and the breeze from the land lakeward 
from 9 or 10 P. M. until sunrise. 
The modifying effect of these large bodies of water upon land 
areas contiguous to the lakes is noticeable. At Milwaukee, 
Wis., which is directly upon the shore of Lake Michigan, the 
mean annual temperature is as follows: winter, 24° F., spring, 
41° F., summer, 67° F., autumn, 49° F., annual range, 110° F. 
At points in the same latitude but. from 50 to 100 miles inland, 
the mean winter and autumn temperatures are about 2° F. 
lower, and mean spring and summer temperatures nearly 5° F. 
higher, while the annual range is about 5° F. greater. 
Art. XXXII. — Mineralogical Notes from the Laboratory of 
Hamilton College; by ALBERT H. CHESTER. 
1. FUCHSITE. 
THIS interesting variety of mica occurs in considerable abund- 
ance on Aird Island, a small island in the northern part of Lake 
Huron near the mouth of the Spanish River and conséquently 
in the district of Aleoma, Canada. The matrix is a coarsely 
crystalline dolomite, and in this the fuchsite occurs in small 
layers and masses, sometimes associated with white quartz and 
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