THE ELEMENTS OF THEORETICAL AND DESCRIPTIVE ASTRONOMY. For the use of Colleges and Academies. BY CHARLES J. WHITE, A.M. ASSISTANT PROFESSOR OF MATHEMATICS IN HARVARD COLLEGE. SECOND EDITION, REVISED. PHILADELPHIA: CLAXTON, REMSEN & HAFFELFINGER. HARVARD COLLEGE LIBRARY Entered according to Act of Congress, in the year 1869, by CHARLES J. WHITE, in the Clerk's Office of the District Court of the United States for the District of Maryland. f I in large type PREFACE. I HAVE endeavored in this treatise to present the main facts and principles of Astronomy in a form adapted to the course of instruction in that science which is commonly given at colleges and the higher grades of academies. I have selected those topics which appear to me to be both the most important and the most interesting, and have arranged them in the order which experience has led me to believe to be the best. I have endeavored, in the descriptive parts of the work, to give the latest information upon every topic which is introduced. The distances and the dimensions of the heavenly bodies, together with other numerical data which depend for their values upon the value of the solar parallax, are given to correspond with the new value which is now adopted in the American Ephemeris. The results of the observations made at the United States Naval Observatory upon the November showers of the last two years will be found in the Chapter on Meteoric Bodies. Some description has also been given of the spectroscope, and of the many interesting discoveries made with it concerning the constitution of the heavenly bodies, and, very recently, concerning the real motions of the stars. No clear conception of the processes by which most of the fundamental truths of Astronomy have been established can be attained without some knowledge of Mathematics. I have endeavored, however, to confine the theoretical discussions within the limits of that moderate mathematical know 3 ledge which may fairly be expected in those readers for whom the treatise has been prepared. Certain definitions and formula, with which the student may possibly not be familiar, will be found in the Appendix; and, with the aid of these, I believe that any one who has had the slightest mathematical education can read every portion of the work without difficulty. The treatises which I have especially consulted in the preparation of this book are Professor William Chauvenet's admirable Manual of Spherical and Practical Astronomy, and an elaborate treatise on Descriptive Astronomy, by George F. Chambers, recently published in England. An interesting chronological history of Astronomy, taken from the latter work, will be found in the Appendix; and Plates II., III., and IV. are from the same source. Plate I. is from a French work by Camille Flammarion, entitled La Pluralité des Mondes Habités. I am indebted to my friend Professor George A. Osborne, of the Massachusetts Institute of Technology, for his kindness in revising my manuscript. I trust that this treatise, although prepared especially as a text-book for students, may be of interest to others who may wish to know the general principles and the present state of the science of Astronomy. HARVARD COLLEGE, CAMBRIDGE, MASS., March, 1872. C. J. W. |