THE PLANETARY AND STELLAR WORLDS: A POPULAR EXPOSITION OF THE GREAT DISCOVERIES AND THEORIES OF MODERN ASTRONOMY. BY O. M. MITCHEL, A. M. DIRECTOR OF THE CINCINNATI OBSERVATORY. LONDON: PARTRIDGE AND OAKEY, PATERNOSTER ROW. - MDCCCLII. PREFACE. A FEW words in explanation of the circumstances under which this volume is presented to the public, may not be unacceptable to the reader. It is now a little more than six years since the writer conceived the idea of erecting a great astronomical observatory in the city of Cincinnati. My attention had been for many years directed to this subject, by the duties of the professorship, which I then held in the college. In attempting to communicate the great truths of astronomy, there were no instruments at hand, to confirm and fix the wonderful facts recorded in the books. Up to that period our country, and the west particularly, had given but little attention to practical astronomy. A few individuals, with a zeal and ardour deserving of all praise, had struggled on to eminence almost without means or instruments. An isolated telescope was found here and there scattered through the country; but no regularly organized observatory with powerful instruments, existed within the limits of the United States, so far as I know. To attempt the building of an observatory of the first class, and to furnish it with instruments of the highest order, without any aid from the general or state government, but by the voluntary contribution of all classes of citizens, was an enterprise of no common difficulty. To ascertain whether any interest could be excited in the public mind, in favour of astronomy, in the spring of 1842, a series of lectures was delivered in the hall of the Cincinnati College. To give an increased effect to the discourses (which were unwritten, and in a style of great simplicity), a mechanical contrivance was prepared, by the aid of which the beautiful telescopic views in the heavens were presented to the audience, with a brilliancy and power scarcely inferior to that displayed by the most powerful telescopes. To this fortunate invention were these lectures, no doubt, principally indebted for the |