The following will show, in a condensed form, estimates of the mean length, breadth, depth, area, and elevation of the several collections of water:

Mean length, Mean br'th, Mean depth, Elevation, Area in squ.

feet.

Michigan occupies a central position, between the extremes, and uniting with the upper division of the St. Lawrence basin, having an area of forty-three thousand five hundred square miles on the lower, or peninsula proper, and twenty-seven thousand square miles on the upper peninsula; making an aggregate of seventy thousand five hundred square miles.

The Lakes and Lake Coast.

These constitute a prominent feature, and must be of great and increasing interest, connecting the agricultural with the commercial enterprize of Michigan, As no state with the location so distant from the seaports, has done more in the same short period to develope the advantages to be derived from its internal resources, none can be in a situation better to reap the advantages arising from an extended inland coast.

If the distance by meanders of the shore of the lakes, and indentations of the bays, were to be made the standard for the length of the coast, it would amount to more than twice that of another, run without regard to the sinuosities of the shore.

The exact distance from the foot of lake Huron, (near Fort Gratiot,) at a point where the north line of township number six north, and range number seventeen west, intersects the water to Middle Island, by meanders, is 345 miles, including Saginaw bay. The same distance on a direct line is only 143 miles; thence to Mackinaw, 97 miles; but by meanders, including the False and True Presque Isles, the distance would be increased to 150 miles; making a total by meanders of 495 miles, and by a direct line, 240 miles.

If the eastern shore of the peninsula appears so irregular and deeply indented with bays and harbors, the western is not less so, particularly in the northern part. The difference will be pro

portionally greater, as the Little and Grand Traverse bays are larger, excepting Saginaw bay, than the largest bays on the eastern side; but as a small part only of the western shore has been surveyed, the subject will not admit of a more extended notice at this time.

Many doubts have heretofore existed in relation to the number and convenience of harbors. A minute examination of the shores, has, however, removed much of the prejudices against the navigation of the lakes, and there is probably no line of coast of equal extent (being seven hundred miles,) that will, with inconsiderable improvements, furnish a greater number of good harbors. Much of the apprehended danger has arisen, therefore, from ignorance of these facts, and the localities of the numerous sheltered bays which would afford protection at all seasons; and as but few if any attempts have been made by actual navigators to explore for themselves, and being without charts, it is no wonder that representations of danger should have obtained, and the dread of shipwreck on an apparently desolate coast, magnify in a great degree the fears attendant on crossing these inland seas.

Depth of the Lakes.

The depth of the lakes has been a subject of speculation, from the earliest period of their discovery by Europeans. Tables have been constructed, and the areas and contents of each endeavored to be ascertained. Errors have been made in these as well as in their elevation above the ocean; in the latter case, however, little is left to conjecture.

Lake St. Clair, an expansion of the straits between Lakes Huron and Erie, eighteen by twenty miles, is much the shallowest, the average depth being only twenty feet. Lake Erie does not exceed eighty-four feet. An ordinary storm disturbs its bottom, and its waters appear turbid. These lakes may be considered as receiving the detritus brought down by the rivers flowing into them, and deposited there. This in particular is apparent around the head of Lake St. Clair, where alluvion islands are constantly forming.and in spring choke up the numerous channels at the mouth of the St. Clair river, extending in the form of a delta far into the lake. The same remark may be made in respect to the west end of Lake Erie, where detritus extends some miles from the mouth of Maumee river; the channel is often devious, and a prevailing westerly wind reduces the lake to less than one fathom.

Lakes Michigan and Huron have undoubtedly the deepest chasms. Receding from the shore, their waters deepen uniformly, and their exist no ceutral shoals or islands, showing in any manner a broken or alpine formation at their bottoms. It is only in the straits of Mackinaw, and above and around the Georgian or Manitou bay of Lake Huron, that islands and shoals make

their appearance. The channels among these islands, however, are only chasms through rocks, caused by abrasion from the waters of the lakes. Soundings have been made to the incredi ble depth of eighteen hundred feet, without reaching the bottom, and the most experienced ship masters do not hesitate to assert the average depth to be more than one thousand fect. Lake Superior, though larger, cannot be considered deeper than the others, for reasons already assigned. It abounds with islands, many of which are large; Isle Royal is one hundred miles long. Primitive masses of rock lie disrupted above and below its surface in every direction, and a permanent impression is left that a chasm, shapeless in its exterior, as well as its interior dimensions, fed by springs and tributary rivers, are the great features of this lake, at a depth of nine hundred feet.

Mountain districts, as has been heretofore observed, may be cut through by rivers, causing deep vallies and depressions, but nowhere on the continental surface of the globe can be found so deep chasms as the basins of these lakes. Though elevated 596 feet above, their bottoms are more than 400 feet below the level of the ocean. Their superficial area is 94,000 square miles, and they contain 11,300 cubic miles of water; a quantity more than half of all the fresh water on the earth.

Interior Peninsula Lakes,

Neither is the subject of the lesser interior lakes on the peninsula, so far as their number and magnitude are ascertained, to be overlooked, forming as they do by their frequency, a great contrast in the topography of this, to that of the other states.

line

From the Ohio and Indiana line on the south, up to range number seven rorth, including all south of the northern railroad, an extent of 9,688,320 square acres, there are 1,425 of these lakes, occupying areas of from one to thirty-five hundred square acres each. Their waters are remarkably cool and transparent, and give to the landscape a highly picturesque appearance. To apply the principles of hydrography in ascertaining their aggregate extent, becomes the more difficult, since, in addition to their great number, no two are of the same dimensions. The following, however, will be found to approximate the truth: allowing each lake an area of 160 rods square, we shall give to the whole 228,000 acres, an extent equal to nearly ten townships, and somewhat larger than Lake St. Clair; and a proportion of about one acre of water to every thirty-nine of dry land.

All the rivers in the state have their sources in groups of these lakes, and they are the fountains of the unremitting volumes that flow through the thousand channels of our streams. While the rivers of neighboring states have measurably disappeared during the drought of the last summer, and caused derangement

in their commerce, ours have suffered comparatively little diminution.

Periodical Rise and Fall of Water in the Lakes.

This interesting question has given rise to a variety of curious seculations. The inference drawn from the following data, it is presumed, will not be altogether inconclusive.

Calculations may be made sufficiently accurate to determine nearly the amount of surface drained, "and if our climate shows a successive series of cold and moisty years, and a series of warm or dry ones, mutually following each other," variations in the volume of water, cannot but necessarily he great.

Taking into our account only the central and upper divisions of the St. Lawrence valley, from Niagara to the northwest angle of Lake Superior, embracing all the country whose streams are tributary to the lakes, we have, by the following table of sections, 248,755 square miles of surface, besides that of the lakes.

Superfices Drained by the Central and Upper Divisions of the St. Lawrence Basin.

N. E. of Lake Superior, from Mackinaw to Nipigon river,.
N. W. of Lake Superior, from Nipigon to St. Louis river,.

Peninsula between Lakes Michigan and Huron, and west end Lake Erie,.

South of Lake Erie to Niagara,.

Add area of Lake Superior,.

32,000

66 Green Bay,.

2,000

66

Lake Michigan,

22,400

66

Lake Huron,...

20,400