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282 a discontinuous current, and, although the instrument is capable of showing the variations of a continuous current, the author did not have this application in mind when he constructed it. No patent was taken out for the device, for the inventor believed that "a scientific man should place no restrictions upon his work which would tend to prevent the repetition of an experiment of scientific interest. A full description should have been published. This was at first delayed, from the pressure of other work, and lack of appreciation of the importance of the results. Afterward I was unwilling to enter into a controversy, or to obstruct my friends, who were struggling to obtain proper recognition of the great results they had obtained in the same field."

What Ice can do.—The important part in producing or modifying topography that has hitherto been conceded to moving masses of ice has recently been disputed by some American geologists, who have denied that ice possesses any eroding or excavating power. Professor J. S. Newberry has published an article sustaining the old theory against these contradictions by evidences drawn from the visible action of living glaciers, as in the Alps, and also in the mountains of Oregon, where a remarkable monotony of surface has been produced by ice-action. The crest of the Cascades, crowned by the volcanic peaks, Mount Jefferson, Mount Hood, etc., has sides sloping east and west, like the roof of a house. These slopes are planed down, and their asperities removed, everywhere showing the effects of a powerful grinding agent. In the Laurentian belt north of the lakes, where were formerly high mountains, are now only low hills and rolling surfaces, and the strata are "standing at high angles but planed down, scratched and ground by glaciers, until their cut edges are like boards in a floor." Similar work has been performed between the Hudson and the Connecticut. The action of running water on topography is not only different from that of ice, but antagonistic to it. Water deepens the lines of drainage and increases the asperities. The cañons of the Colorado are typical and characteristic illustrations of water action on continental surfaces. Great ice-sheets, on the contrary, tend to reduce all asperities, fill depressions, and render the topography monotonous. If ice is competent to do the work of shaving and smoothing the landscape, which the author aims to prove by his citations that it has done, much more may it have excavated lake-basins. "The power which has done the greater is certainly equal to the less." Probably, Professor Newberry adds, some misapprehension arises from an inadequate conception of the composition and action of a glacier. "It is, perhaps, regarded as a mass of pure ice, which by itself would have little grinding power; but a glacier is a great moving mass which by its weight and motion crushes and removes all but the most solid rock prominences over which it passes. Where it impinges against cliffs, these are sometimes lifted, and huge blocks are carried away. In many localities we find stones hundreds of tons in weight, which have been torn from their beds and carried many miles. Pure ice, then, in sufficient volume is a potent and almost irresistible agent of erosion, quite independent of its grinding action; but, as a matter of fact, all glaciers are studded below with rock-fragments, great or small, which they have torn up in their course; so that sand, gravel, and bowlders constitute a coating to the under surface of a glacier which may be compared with the emery on a copper wheel."

Have we gone too far in draining Swamps?—In one of a series of papers on "The Proper Value and Management of Government Timber-Lands," read at the Department of Agriculture, in May last, Mr. M. C. Read showed that harm rather than good has been done by the draining of the swamps which has been so vigorously prosecuted during the last twenty-five years. The swamps were constant store-beds and sources of moisture, and tended to keep the streams that drew upon them at an even level. In draining them, they being generally found on the same level as the surface of adjacent lakes, the outlets of the lakes were deepened so that they could be drained more speedily and completely. To accommodate the more rapid outflow that accrued, the streams below were often straightened and cleared out, and the rapid concentration of the water into the larger streams was