Page:Popular Science Monthly Volume 16.djvu/87

 a well-demonstrated fact that the volume of water escaping from the lakes through the mighty St. Lawrence is far greater than the amount discharged from the upper lakes into Ontario by the proper channels—the St. Clair and Niagara; and it is also well settled that the supply of Lake Erie from St. Clair is about equaled by its discharge through the Niagara; showing that it receives from no subterranean source any perceptible surplus of water. And this is generally attributed to its comparative shallowness as compared to the greater depth of Superior, Huron, and Ontario"—from which it follows that the immense difference between the outflow and the inflow of Ontario is due to its greater depth, thus making it a possible deep spring; and that this applies also to the other deep lakes; and that Superior, Huron, and Ontario, and possibly Michigan, are overflowing springs of subterranean water. The conclusion is therefore inevitable that this great overflow must be accounted for upon some other hypothesis than that of hydraulic pressure, since there is no higher land which could furnish an adequate supply. Indeed, if we suppose all the land on the continent which is higher than Lake Superior to be but shells tilled with water, the difference between the outflow and inflow of Ontario would exhaust the supply in a short time. But the subterranean supply is known to be constant, and has always been so. But Mr. Howell supposes this vast surplus in Ontario to come through a subterranean channel, connecting it with Superior. And here, again, we must thank Mr. Howell for his facts. The surface of Superior is, he says, 600 feet above the sea, and Ontario but 235 above. Therefore, the difference of level between the two is 365 feet. If this channel exists as supposed, the surfaces of these lakes would find a common level, instead of a difference of 365 feet!

Mr. Howell, in presenting the proof that there is a great underflow from Superior southward under the valley of the Illinois River, says: "And here on this bank of the old Illinois, opposite the junction of the Fox River, are the celebrated Mineral Springs. . . . These waters are somewhat similar to the waters of Saratoga County, New York," which certainly proves that they do not come from Superior, the waters of which are not of this class. The editor of "Scribner's Monthly" naively adds this note: "Whether the Great Lakes are the true reservoirs from which our Northern wells, springs, and subterranean streams receive their constant supply of water, is a question of sufficient interest and significance to merit a thoughtful consideration. The data upon which the advocates of this theory found their conclusions are manifold and forcible, and, though there may be breaks in the line of evidence, the facts as now established would seem to favor the views which the author of this paper now proposes to define and defend." While Mr. Howell presents strong evidence of a possible underflow from Superior southward, he has hardly claimed that the general supply of the "Northern wells, springs, and subterranean streams,"