BY H. N. ROBINSON, A. M., FORMERLY PROFESSOR OF MATHEMATICS IN THE U. 8. NAVY; AUTHOR OF A TREATISE ALBANY: ERASTUS H. PEASE & CO., 82 STATE STREET CINCINNATI: JACOB ERNST, NO. 183 MAIN STREET. Asto: 8092./ 1867 but 31 Entered, according to act of Congress, in the year 1849, BY HORATIO N. ROBINSON, In the Clerk's Office of the District Court of the United States, for the District MICROFILMED 5 P R E F A CЕ. To give at once a clear explanation of the design and intended character of this work, it is important to state that its author, in early life, imbibed quite a passion for astronomy, and, of course, he naturally sought the aid of books; but, in this field of research, he was really astonished to find how little substantial aid he could procure from that source, and not even to this day have his desires been gratified. Then, as now, books of great worth and high merit were to be found, but they did not meet the wants of a learner; the substantially good were too voluminous and mathematically abstruse to be much used by the humble pupil, and the less mathematical were too superficial and trifling to give satisfaction to the real aspirant after astronomical knowledge. Of the less mathematical and more elaborate works on astronomy there are two classes-the pure and valuable, like the writings of Biot and Herschel; but, excellent as these are, they are not adapted to the purposes of instruction; and every effort to make class books of them has substantially failed. From the other class, which consists of essays and popular lectures, little substantial knowledge can be gathered, for they do not teach astronomy; as a general thing, they only glorify it; they may excite our wonder concerning the immensity or grandeur of the heavens, but they give us no additional power to investigate the science. Another class of more brief and valuable productions were, and are always to be found, in which most of the important facts are recorded; such as the distances, magnitudes, and motions of the heavenly bodies; but how these facts became known is rarely explained: this is what the true searcher after science will always demand, and this book is designed expressly to meet that demand. In the first part of the book we suppose the reader entirely unacquainted with the subject; but we suppose him competent to the task-to be, at least, sixteen years of age-to have a good knowledge of proportion, some knowledge of algebra, geometry, and trigonometry-and then, and not until then, can the study be pursued with any degree of success worth mentioning. Such a person, and with such acquirements as PREFACE. |