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It must not be thought that meteors usually strike the earth. In truth, but few of them do. The earth is surrounded by them, cold, dark, invisible, because unillumined. It is only when they become heated by rapidly impinging on the atmosphere that they can be seen at all; and unless they come near enough to become subject to the dominant power of the earth’s attraction, they pass off into space unnoticed, and their presence unsuspected.

JAMES H. COFFIN,

Late Professor of Astronomy, Lafayette College, Easton, Pa.

A case in point is the brilliant “fire-ball” of July 20, 1860, that moved rapidly over the United States, from Wisconsin to Cape Cod, and then passed off into the skies. The entire time of its visible flight over a path of thirteen hundred miles was about two minutes. It was seen about ten o’clock in the evening. It was estimated to be from one hundred to five hundred feet in diameter, allowing for an increase as it expanded by reason of its striking with such velocity the lower and denser layers of the air. Its size and brilliancy were such as to arrest the attention of hundreds of persons, some of whom crouched in fear, and even alleged that they heard it hiss as it flew over their heads. Some fishermen in Lake Huron had ropes over the sides of their boat, ready to spring into the water if it came too near.

James H. Coffin, LL.D., then Professor of Astronomy in Lafayette College, made an exhaustive study of this unusual phenomenon, and, under the patronage of the Smithsonian Institution, published a volume containing many observations that he collected, with the mathematical results derived from them. Professor J. Hann, of Vienna, the highest authority on this subject, said that it was the most comprehensive study of a meteor’s path ever accomplished. Six years were spent in making the computations.

Self-illumined by the heat evolved in striking the various layers of the earth’s atmosphere, it became sufficiently bright to be first seen when seventy miles above the surface of the earth. It was within forty miles of touching us at the time it was over the Hudson River, when the great heat acquired by its rapid transit caused it to burst into two masses, which—like Biela’s comet—continued to pursue separate courses, side by side, until they were lost to view in their ascending flight, being last seen from the deck of a vessel off the island of Nantucket.

No part of the fire-ball struck the earth. Its orbit was an hyperbola, a curve not often found in nature, such that it can never come near us again unless, by the superior attraction of some celestial body, its course may be changed, and a new orbit result.