TABLE II.-Register of Observations made at Copper Harbor, Lake Superior, from July 15th to 29th, Lat. 47° 28' N.; Long. about 88° W. of Greenwich. 200 80 Water higher than usual, al-Wind blowing towards a bea- 480 "11 20" Water suddenly fell one foot, Wind S.E. 4. Wind N.w. 9; constant roar Calm. 66 Water a foot lower than usu-Calm; clearing in N.w., and al, and flowing into bay current. sun soon came out. 20063 Water high in bay. -200 68 Water fallen 9 in. in 5 min- 204 68 Water 4 inches lower than 66 "4. " 4. Very strong breezes. by w. 5; Water stationary in bay and Very strong breeze s. by w. 6 "222" Water rising rapidly in bay. Very strong breeze s. by w. Throughout the preceding table where time is registered, fluctuations in the level of the water were observed, though the amount of rise and fall was not always registered. As a general thing, fluctuations in the barometer accompanied the fluctuations. in the level of the water; but sometimes the water level varied rapidly in the harbor, while no such variations occurred in the barometer at the place of observation. These variations in the level of the water, may be caused by varied barometric pressure of the air on the water, either at the place of observation, or at some distant point. A local increased pressure of the atmosphere at the place of observation, would lower the water level where there is a wide expanse of water; or a diminished pressure under the same circumstances, would cause the water to rise above its usual level. If the barometer remain stationary at the place of observation, an increased pressure at a distant part of the lake would cause the water to rise; and a diminished pressure at such a point, would cause it to sink at the place of observation. ring the last three summers, I have been on and near the coast of Lake Superior, much of the time coasting in a boat, and encamping on the shore. I have often observed at the mouths of streams, when encamped, that the outward flow of the water would be interrupted, and a strong current flow into the river or creek un Du til the water was raised from two or three to sixteen or eighteen inches above its common level, and after remaining thus for a few minutes or sometimes a longer period, again flow into the lake with a strong current, until the usual level of the water on the bar is attained. Sometimes the water of the lake would also recede below its usual level, so as to leave the bars naked that were generally covered with water. Toward the extremities of long lakes and bays, the 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, observed by many persons, and carefully registered by Mr. Cass in 1828, and by Lieut. Ruggles in Sept. and Oct., 1836, are believed to be due to the influences of the wind in part, but mostly to variation of atmospheric pressure. Copper Harbor is situated nearly in the centre of Lake Superior, 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 concerned in producing variations of level. The place of observation (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. Copper 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 perceived 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 considerable 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 to me instances in which the smooth flat rocks at the head of the 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 a half feet lower than usual. A daring New England man wishing to see if the falls could be ascended, made the attempt in a sharp skiff sail boat, with a strong fair wind, almost a gale, and succeeded a thing never before attempted, or even deemed possible. SECOND SERIES, Vol. VI, No. 16, July, 1848. 3 A heavy rain storm from the N. and N.w. succeeded on the following day. Many observing men on the lakes have noticed that the extraordinary variations in the level of the water precede a storm. I regret that I did not accurately note down more of them. The preceding notes may call the attention of those favorably situated for these investigations, carefully to observe the attending circumstances, and especially the barometric fluctuations, wind, weather, and temperature. A rise of the barometer in the annulus of a storm precedes the depression, and would account for the fluctuations of level, whether the variations in atmospheric pressure occur at the place of observation or at some distant point, on a broad expanse of water. Periodical Rise and Fall of Lake Superior.-The gradual rise and fall of the level of the water in the great lakes, through a series of years, has long been noticed. Its cause is doubtless due to a greater quantity of rain and snow, or of a lower mean of temperature and diminished evaporation during the period of rise, and the reverse during the time of fall of the water-level of the lakes. During the year 1838 or 1839, the waters were higher than they had been before for at least two centuries. This is demonstrated by the large tracts of land that were inundated, which are covered with forest trees, many of them the growth of ages. These trees were destroyed by this overflow around Lakes Erie and Huron and on the St. Mary's river, between Point Detour and the Sault St. Marie. We have no accounts of Lake Superior at that time, and I have seen no similar tracts of destroyed timber on the shores of that lake, although I have coasted along most of the shore. There are facts however that indicate a marked variation within a few years. In 1845 a rock in the middle of the entrance of Eagle Harbor showed itself only in the trough of the waves; and the narrow inlet betwen the west end of Porter's Island and the main land at Copper Harbor, was of such depth that loaded Macinaw boats could enter Copper Harbor without touching the rocks. In the summer of 1846 the rock at the mouth of Eagle Harbor was a foot and a half above water; boats could not get into Copper Harbor through the inlet above mentioned, and skiffs and canoes rarely attempted to enter by that passage. In June, 1847, the rock above mentioned was still more out of water, and the western inlet to Copper Harbor could be crossed, by stepping on the projecting points of the reef, without wetting the feet; and during some depressions of the water by barometric waves, it was laid almost entirely dry. From the 18th of June to the 6th of September the general level of the water rose fully twelve. inches. Several large rocks in the water opposite the government house, with their points projecting at different heights above |