Page:Popular Science Monthly Volume 41.djvu/816

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winter. Occasionally storms depart very much from the average track, their course being sometimes directed toward the southeast and sometimes toward the northeast, and occasionally their course for a day or so has been almost exactly north. Their average velocity of progress is twenty-six miles per hour, being twenty-one miles in summer and thirty miles in winter; but sometimes they attain a velocity of fifty miles in an hour, and sometimes they remain for a day or two sensibly stationary."

Blodgett, Mitchell, Coffin.—Several other names deserve mention, as belonging to earnest investigators and theorists in the early fields of American meteorology. Loren Blodgett, M. N. I., published in 1857 a work on the climate of the United States, far superior to anything previously sent out. About the time of Redfield's earlier work, Prof. Mitchell, of the University of North Carolina, propounded a theory which seems to have attracted but little attention—as indeed it deserves but little—maintaining that certain storms, especially those of the Atlantic coast, are the result of a gyratory motion about an axis parallel to the plane of the horizon. This proposition he held in opposition to Redfield, whom he mentions as contending for the revolution of the wind about an axis perpendicular to the plane of the horizon. This speculation of Prof. Mitchell was of less value to science than his suggestion of the plan of daily maps, showing the aspects of the sky, that cloud boundaries might be traced, and thus their extent and movements discovered an idea which is incorporated into the every-day work of the Signal Service at Washington. Still another of the meteorologists of service in the line of investigation we are describing was Coffin, the author of Studies in the Winds of the Northern Hemisphere.

Dr. Joseph Henry.—When the study of the laws of storms and their movements in America had gone as far as this, it had reached a point beyond which it could not proceed without a more abundant material in the way of observations and statistics. More data were required, if larger demonstrations were to be made. The time had come when no great advance in the knowledge of storms could be had, unless they were carefully studied over large areas, their actions noted at a great number of points at once, and the information thus gained reduced to order. Of no other science is this so true as of meteorology; of no branch of meteorology is it so true as the observation of storms. Eternal vigilance is the price of all knowledge in this great field. And we are now at a point in the progress of the study of American storms when a great advance was made. Prof. Joseph Henry, the Director and Secretary of the Smithsonian Institution, and one