Page:Popular Science Monthly Volume 3.djvu/523

Rh from the theory of the winds of the globe, which considers them as due to the combined action of the movement produced in the air by the greater heat of the equator, and the rotation of the earth on its axis.

The researches of Prof. Coffin also strikingly exhibit the fact of the influence of the seasons in modifying the direction of the wind, or in producing the results denominated monsoons. Thus, along the eastern coast of North America, as is shown on the maps, the tendency during the summer months of the opposing forces is to lessen the dominant westerly wind, and this effect is noticed even beyond the Mississippi, as well as in the Atlantic Ocean along our coast. The effect is, undoubtedly, due to the change of temperature in the land—the temperature of the ocean remaining nearly the same during the year, while that of the land is greatly increased in summer above the mean, and depressed in winter. From this cause the air will tend to flow toward the centre of the continent from the ocean in summer, and from the same centre toward the ocean in winter.

The results of the investigations of Prof. Coffin have been referred to in all the treatises on meteorology which have appeared since their publication, and they have been employed with other materials as the basis of the wind-charts of the Atlantic and Pacific Oceans, prepared and published by the English Board of Trade.

In attentively studying the result of Prof. Coffin's labors, we cannot but be struck with his conscientious regard for accuracy, and his devotion to truth. In all cases in which the results do not conform to the theory which explains the general phenomena, the discrepancies are fully pointed out; and, where he is unable to suggest an hypothetical cause of the anomaly, he candidly acknowledges his ignorance. In this respect he is an admirable example of a successful investigator, since errors in science as frequently occur from defects of the heart as from those of the head.

After the publication of the work on the winds, he continued to collect materials, at first with a view to an appendix, and finally extended his investigations to the winds of the entire globe. To aid in this enterprise, the Smithsonian Institution placed in his hands all the observations on the winds, which it had obtained from its numerous observers during the twenty years since the system was commenced, together with the observations made by the officers of the army, as well as the extensive series of materials in the various series of transactions of scientific societies of the Old World, obtained through the exchanges of the Institution. This work, for several years past, Prof. Coffin prosecuted with unremitting assiduity during all the intervals which could be spared from his laborious professional duties. Unfortunately, however, he was not spared to complete the work, although it is in such a condition as to be readily finished under the direction of the principal assistant employed by Prof. Coffin. It is