and nee of Level in Lake Superior. 17 
bar is attained. Sometimes the water of the lake would also re- 
cede below its usual level, so as to leave the bars naked that were 
generally co with water, Toward the extremities of long 
lakes and ba e wind causes very sensible fluctuations in the 
level of the water, which have long been observed at Whitehall 
and Buffalo, N. Y. The variations in level in Green Bay, obser- 
ved by many persons, and carefully registered by Mr. Cass in 
1828, and by Lieut. Ruggles in Sept. and Oct., 1836, are believ- 
ed to be due to the eeences, < the wind tz part, but mostly to 
variation of atmospheric pre 
Copper Harbor is i eal in the centre of Lake Supe- 
rior, near the extremity of a peninsula extending about seventy 
miles into the lake; and whatever may be the direction or force 
of the wind, the water retains its level so far as this cause is con- 
cerned in producing variations of level. The place of observa- 
tion (on Porter’s Island) is entirely sheltered from any influence 
of the waves, which break with great force in storms on the reefs 
and shore, on the outside of the island. It is in a little bay on 
the south side of the island, and opens into Copper Harbor. Cop- 
per Harbor is three miles in length parallel to the lake coast, and 
opens with a breadth of a mile. Any fluctuations that are not 
momentary, like those of the waves produced by wind, are per- 
ceived in a few minutes at the place where the observations were 
made, both by the variation of level, and by the rapid flow into 
or out of the harbor in the narrow opening that separates the west 
end of Porter’s Island from the main land. 
The quantity of water flowing through the rapids at the Sault 
St. Marie, at the outlet of Lake Superior, is subject to very con- 
siderable variation, and is dependent on two causes, viz., the 
direction and force of the wind, and, second, upon barometric 
waves. Capt. Peck, who resides at the Sault ‘St. Marie, related 
rapids were bare for a considerable distance on or near the Canada 
shore, where ordinarily there was a strong current. He had 
walked far out on these rocks, but observation had taught him 
not to tarry long, as the water would return sometimes in half an 
hour ; these depressions of the water usually preceded a storm. _ 
During my visit to the Sault on the 7th of Sept. last, the water 
was remarkably low on the rapids all day, being one ‘and halt 
feet lower than usual, A daring New England man v 
see if the falls could be ascended, made the attempt pig 
skiff sail boat, with a strong fair wind, almost a of and st 
ceeded—a thing never before attempted, or even deemed ' 
- Seconp Serizs, Vol. VI, No. 16, July, 1848. 3 
