effect of "local attractions." I had doubted the correctness of their observations, but I am fully convinced that these changes are at least as great as they represent them. Part of the region traversed had been surveyed by Mr. Burt, with his solar or equatorial compass-an ingenious contrivance, which measures constantly the sun's azimuth, and indicates the variation at any time of the day, during clear weather, by a solar spectrum; this presumes the latitude and sun's declination to be known, and the instrument to be adjusted accordingly.

I have already anticipated one of the uses to which a knowledge of the elements of terrestrial magnetism may be applied, viz: the discovery of some species of iron ores. It remains to make a few observations on a prop. osition which has been agitated for two years before the Congress of the United States, viz: to use the elements of magnetism as the means of determining the latitude and longitude for nautical and geographical purposes. The agitators of this proposition seem to have taken it for granted that the magnetical lines, meridians, equator, poles, &c., bear the same relation to the terrestrial lines and points of the same name, as the ecliptic and its secondaries bear to them; being that of two concentrical spheres, whose axes cross each other at an angle of 23° 28'. This should have been called a theory, not a "discovery" for it contradicts, directly, well-observed facts, and disagrees with the observations recorded in this paper. Should Congress see fit to send the projector of this theory, or any qualified person, abroad to make magnetical observations, and make an appropriation for that purpose, it would meet the approbation of the learned throughout the world. But, that a splendid speculation should be agitated by persons who, however well qualified as men of literature and as politicians, are not adepts in the modern science of magnetism and electrology-that an amount of national treasure sufficient to have erected a magnetical observatory, should have been spent on a project which every magnetician in the country foresaw was absurd-are subjects much to be regretted, and are calculated rather to injure our national reputation for physical science. On this subject, I concur fully in the sentiments of Dr. Patterson and Mr. Walker, published in the Proceedings of the American Philosophical Society, for July and August, 1838.

I may be called upon to specify what I have charged in general terms; there is no end to words, and this is no place to go into a long argument.

It is asserted in that theory, that "the line of no variation is a great circle of the earth." Those who have actually surveyed that line, report it as being very irregular, and not a great circle. The lines of equal variation, as observed and reported in the returns of the surveyors of western parts of the United States, proceed southwardly, and curve rapidly to the west. If, as observations seem to indicate, the elements of magnetism are subject to all of the changes previously named, being affected by progressive changes, by summer and winter, by day and night; and, also, like the barometer,. by irregular, unforeseen causes; they will, for the present, scarcely answer as a substitute for astronomical observations in determining geographical position.

V.-EARTHWORK ANTIQUITIES IN WISKONSIN TERRITORY.

I present this subject, not as a discovery, but merely to add such evidence to the discoveries and publications of others as seem, from the doubts I have heard so repeatedly expressed, to be necessary to convince the majority of readers of their correctness. In the 34th volume of "Silliman's Journal," is a communication from Richard C. Taylor, Esq., on the subject of these identical works, in which he describes them as being "in the form of animal effigies." The figures given by Mr. Taylor are so unlike any ancient tumuli in other parts of the country, that I had, ever since noticing them, felt a strong desire to examine the originals. On entering Wiskonsin, I was so engaged in other pursuits that I had forgotten the "effigies," until, upon examining the "sandstone bluffs," eight miles east of the Blue Mounds, I literally stumbled over one of them, overgrown with the rank prairie grass. I was at once convinced of the correctness of Mr. Taylor's representations, and not a little astonished that some well-informed persons there, in the midst of these strange groups, should still pretend to dispute their artificial origin. The same ambition to exercise an independent judgment might lead the same individuals to dispute that the ruins of Herculaneum are artificial; the same argument might be used-" that they just come so in the earth." Without going into any discussion in regard to the origin, history, or design of these figures, I shall merely represent their form and dimensions with as much accuracy as a very particular survey of a few of them enabled me to attain. I shall not even pretend to say that they are like animals; for this the reader can determine for himself. I have not attempted, in any degree, to represent them as they might once have been, but exactly as I found them on the day that I surveyed them.

The method pursued in making the surveys is represented in plate No. 1, Antiquities. Here, for convenience, I make use of the names of the parts of an animal. The figure delineated is the foremost one of two, between which the road passes, and which are on the verge of a small prairie, about ten miles east of Madison, the capital of Wiskonsin. Small stakes were set in the following points, viz: the eye, the fore foot, the shoulder, the hip, the hind foot, and the end of the tail. The angular positions of these and other points were determined by measuring, with a tape measure, the sides of the several triangles which those points form, in such a manner that the determined side of one triangle shall be the base of a new one. After the determination of all the triangles, their several diameters and distances were measured and noted; and, finally, to determine the bearing of the whole figure, the magnetical bearing of the line from the hip to the shoulder was registered on the field-book.

The following is a copy from the field-notes, in reference to the above figures. (See Antiquities, plate No. 1.)

Observations.-Ears distinctly separated. Two trees, sixteen inches. in diameter, growing in the nose. Ground sloping gently towards the feet. Both the fore and hind legs curved a little backwards. The tail a little hollowed on the upper side. Height, or relief of the figure above the natural surface, about three feet; and the back somewhat steeper than the belly. Bearing of hip to shoulder N. 38° W.

It will be seen, by examining the above notes, that they determine twenty-five points in the circumference of the figure; and that the connecting of these points by lines, and thus completing the outline, permits no exercise of imagination. The figure from the earth is simply transferred to the paper on a scale of the one hundred and twentieth part, in linear dimensions. Seven other figures were surveyed with the same degree of particularity, and the distances between them, and the relative positions of the same group, accurately noted. They are represented in the three following plates, on a smaller scale of forty feet to the inch. That which is above described, and represented on plate No. 1, is again represented on the small scale "Plate No. 4, Antiquities," as figure 8.

The "military road" from Prairie du Chien to the Four lakes, after crossing the Wiskonsin river, and ascending a small tributary, occupies the height or dividing-ridge between the waters of the Wiskonsin on one side, and those of Rock river and some smaller streams on the other, for the distance of eighty or one hundred miles, occasionally descending into a moderate valley, and crossing a small rivulet, a head branch of some of the incipient: streams. Most of the route is on a high open prairie. From the Blue Mounds eastward to the Four lakes, the country abounds with the earth