It will be seen how discovery started from a casual hint based on the observations of a keen and well-trained mind; how it was stimulated in a later observer, who bent himself to the painstaking collation of facts bearing on one special set of phenomena; how these facts finally warranted him in advancing a hypothesis; how this hypothesis was opposed and criticised; how it maintained itself in the face of increasing light; how more extended observations confirmed it and enlarged its application; how it became the basis of all subsequent investigation; how it was sustained by the testimony of other observers working along similar lines; and how to-day it is at the very corner-stone of the meteorological science in America. To this narrative let us turn.
It may be fairly presumed that the well-known suggestions of Benjamin Franklin, based on the occurrence of a northeasterly storm in Boston shortly after one was noted in Philadelphia, was the first definite contribution to the scientific knowledge of North American storms and their movements of transition. Though that contribution was little more than a speculation, it was nevertheless one of those sagacious anticipations of results which marks the true scientific genius. In a letter to Jared Eliot, dated at Philadelphia, July 16, 1747, Franklin says: "We have frequently along this North American coast storms from the northeast which blow violently, sometimes for three or four days. Of these I have had a very singular opinion for some years—i. e., that though the course of the wind is from northeast to southwest, yet the course of the storm is from southwest to northeast; that is, the air is in violent commotion in Virginia before it moves in Connecticut, and in Connecticut before it moves at Cape Sable."
In another letter to Eliot, dated at Philadelphia some two years later (February 13, 1749-'50), Franklin says: "You desire to know my thought about northeast storms beginning to leeward. Some years ago there was an eclipse of the moon at nine in the evening which I intended to observe, but before night a storm blew up at northeast and continued violent all night and next day; the sky was thick clouded, dark, and rainy, so that neither moon nor stars could be seen. The storm did a great deal of damage all along shore, for we had accounts of it in all the newspapers, from Boston, Newport, New York, Maryland, and Virginia. But what surprised me was to find in the Boston newspapers an account of an observation of the eclipse made there, for I thought as the storm came on from the northeast it must have begun sooner in Boston than with us, and consequently prevented such observation. I wrote to my brother about it, and he informed me that the eclipse was over there one hour before the storm began. Since which I have made inquiries, from time to time, of travelers and of my correspondents to northeast and southwest, and