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506, while the services of Prof. Coffin himself, in directing and superintending the whole, were entirely gratuitous.

But the great work to which he owes his celebrity, in all parts of the world, is his treatise on "The Winds of the Northern Hemisphere," published in the "Transactions of the Smithsonian Institution," vol. vi., in 1853. This work had been commenced at least ten years before the date of its publication, a communication having been made in relation to it to the American Association for the Advancement of Science, in 1848.

The materials on which it was based were derived from all accessible sources, including 600 different stations on land, and numerous positions at sea, extending from the equator to the 83d degree of north latitude, the most northerly point ever reached by man, and embracing an aggregate period of over 2,800 years.

The design of the work was to ascertain, as far as possible, the mean direction in which the lower stratum of the air moves in different portions of the Northern Hemisphere, its rate of progress, the modification it undergoes in different months of the year, the amount of deflecting forces, and its relative velocity from different points of the compass. The collection of this material involved an amount of correspondence and bibliographical research which but few would undertake, even with the hope of pecuniary reward, and still fewer for the love of truth, and the acquisition of knowledge for its own sake. But the labor of computation, and discussion of the materials, was an almost Herculean task, to which years of silent and unobtrusive labor were devoted. The work consisted mainly of about 140 quarto tables of figures, with descriptive deductions, and illustrated by maps. Each of these figures is the result of laborious calculations, since the method of determining the velocity and direction of the wind is the same as that employed by the mariner in determining the distance in a straight line, and direction at the end of a given time, from the place of his departure. In this work Prof. Coffin was the first clearly to establish the fact, by accurate comparison of observations, that there are three great zones of winds in the Northern Hemisphere. The first belt is that of the region of the easterly trade-winds, extending northward in the Western Hemisphere to about the 32d degree north latitude, and in Europe to the 42d degree. The second is the great belt around the world of the return-trades, in which the predominant direction is from the west. This extends northward in America to 56°, and in Europe and Asia to about 66° north latitude. Beyond this, principally within the Arctic Circle, is a belt of easterly or northeasterly winds. The common pole of these belts or zones has not the same position as that of the geometrical pole of the earth. It appears to be in latitude 84° and longitude 105° west of Greenwich, and has been denominated by Prof. Coffin the meteorological pole.

These results are in general accordance with the mathematical