A TREATISE ON SHOOTING-STARS, FIRE-BALLS, AND AEROLITES. BY DANIEL KIRKWOOD, LL.D. PROFESSOR OF MATHEMATICS IN WASHINGTON AND JEFFERSON COLLEGE. PHILADELPHIA: J. B. LIPPINCOTT & CO. 1870, Nov. 14. Bowditch Fund. 6/-6 Entered, according to Act of Congress, in the year 1867, by DANIEL KIRKWOOD, LL.D., In the Clerk's Office of the District Court of the United States for the Western District of Pennsylvania. PREFACE. ARISTOTLE and other ancient writers regarded comets as meteors generated in the atmosphere. This opinion was generally accepted, even by the learned, until the observations of Tycho, near the close of the sixteenth century, showed those mysterious objects to be more distant than the moon, thus raising them to the dignity of celestial bodies. An achievement somewhat similar, and certainly no less interesting, was reserved for the astronomers of the nineteenth century. This was the great discovery that shooting stars, fire-balls, and meteoric stones, are, like comets, cosmical bodies moving in conic sections about the sun. DR. HALLEY was the first to foretell the return of a comet, and the year 1759 will ever be known in history as that which witnessed the fulfillment of his prophecy. But in the department of meteoric astronomy, a similar honor must now be awarded to the late DR. OLBERS. Soon after the great star-shower of 1833 he inferred from a comparison of recorded facts that the November display attains a maximum at intervals of thirty three or thirty-four years. He accordingly designated 1866 or 1867 as the time of its probable return; and the night of November 13th of the former year must always be memorable as affording the first verification of his prediction. On that night several thousand meteors were observed in one hour from a single station. This remarkable display, together with the fact that another still more brilliant is looked for in November, 1867, has given meteoric astronomy a more than ordinary degree of interest in the public mind. To gratify, in some measure, the curiosity which has been awakened, by presenting in a popular form the principal results of observation and study in this new field of research, is the main design of the following work. The first two chapters contain a popular view of what is known in regard to the star-showers of August and November, and also of some other epochs. The third is a description, in chronological order, of the most important falls of meteoric stones, together with the phenomena attending their descent. The fourth and following chapters to the eleventh inclusive, discuss various questions in the theory of meteors: such, for instance, as the relative number of aerolitic falls during different parts of the day, and also of the year; the coexistence of the different forms of meteoric matter in the same rings; meteoric dust; the stability of the solar system; the doctrine of a resisting medium; the extent of the atmosphere as indicated by meteors; the meteoric theory of solar heat; and the phenomena of variable and temporary stars. The twelfth chapter regards the rings of Saturn as dense meteoric swarms, and accounts for the principal interval between them. The thirteenth presents various facts, not previously noticed, respecting the asteroid zone between Mars and Jupiter, with suggestions concerning their cause or explanation As the nebular hypothesis furnishes a plausible account of the origin of meteoric streams, it seemed desirable to present an intelligible view of that celebrated theory. This accordingly forms the subject of the closing chapter. The greater part of the following treatise, it is proper to remark, was written before the publication (in England) of Dr. Phipson's volume on "Meteors, Aerolites, and Fallingstars." The author has had that work before him, however, while completing his manuscript, and has availed himself of some of the accounts there given of recent phenomena. CANONSBURG, PA., May, 1867. |