Iowa County democrat. [volume] (Mineral Point, Wis.) 1877-1938, 1902-09-18
WINDS AFFECT TIDES.
Report of the United States Weather
Bureau on Lake Erie.

Bureau on Lake ERIE.
Bulletin J of the weather bureau of
the United States department of
agriculture contains an article with
the above heading, prepared by Al
fred J. Henry, professor of meteorol-
ogy. under the direction of Willis l.,
Moore, chief of the bureau. This re-
port deals with tn" character and
frequency of the storm winds prevail
ing on Lake Erie. the changes in
water level produced by them, and
the possibility of predicting the oc-
currence of the most pronounced
changes in level at the eastern end OF
the lake; and it is illustrated by a
series of profles showing the hourly
and daily fluctuations in levels at
Buffalo, n. Y.
In it's physical features Lake Erie
is about $50 miles long and go miles
wide in its greatest dimensions, and
the area of the lake is about 10000
square miles The bottom contour
divides the lake into three basins
the western, covering about 1900
square miles, with comparatively level
bottom and an average depth of 30
feet the middle basin covering about
$500 square miles. with a shelving
bottom, gradually increasing the
depth to 80 feet, and the eastern
basin, with 2,100 square miles and a
greatest depth of $50 feet, off Long
Point
The prevailing winds are westerly.
At Detroit So per cent. are from a
westerly quarter at Cleveland, 43 per
cent, and at Buffalo 81 per cent. are
from the same point The frictiOnal
action of thes winds piles up the
water on the shore directly opposed to
it, but the currents in the Great
Lakes produced by the winds are
feeble in comparison with those of the
ocean. The area of water is relative
ly small as compared to that of the
land. On account of the shallOwness
Of the water at both ends OF the lake
the disturbance in level due to the
winds is sometimes a serious menace
to navigation. For many years the
United States engineers have main
tanned a tridaily eye observation Of
lake level, and in recent years auto
matte gauges have performed the
same Office, and from these the charts
named have been prepared, referred
to mean tide level at New York
The surface of the lake is never in
absolute repose The first effect of
strong wind seems to be to transfer
from one end of the lake to the other
sufficient water to disturb the condi
ton of hydrostatic equilibrium which
existed previously. After the maxi
mum force Of the wind has been
exerted the lake tends to return to it's
state of stable equilibrium, and this
state is reached by a series of rock
ings of the water Of the whole lake
about a modal line passing through the
centre Of the lake. the water at either
end rising and falling until the condi
ton Of rest is attained This pbenom
enOn is the socalIed "seiche" OF the
Lake Geneva, where it was first OBJ
served, and the term simply means
any rythmic oscillation Of water level
Of short duration obviously not pro.
duced by fluctuations in the water
supply to the lake Prof +. A. Foral.
Of Lausanne, has eXhaustivcly investi-
gated this phenomenon and formulas
are laid down for fixing the time Of
I oscillation
The report details the effect upon
lake levels o. the storm Of December
IT, 1893 when the wind reached a
maximum velocity Of 70 miles per
hour Under the effect Of a south
easterly to southern wind the water