506 THE POPULAR SCIENCE MONTHLY. 



gress, while the services of Prof. Coffin himself, in directing and super- 

 intending 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 re- 

 lation to it to the American Association for the Advancement of Sci- 

 ence, in 1848. 



The materials on which it was based were derived from all acces- 

 sible 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 differ- 

 ent portions of the Northern Hemisphere, its rate of progress, the modi- 

 fication 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 cor- 

 respondence and bibliographical research which but few would under- 

 take, 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 de- 

 parture. 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 de- 



