The main object of the following chapters is to give a brief and simple description of the most important and interesting facts concerning the heavenly bodies, and to suggest to the general reader how much of the ground thus covered lies open to his personal survey on very easy conditions. Many people who are more or less interested in astronomy are deterred from making practical acquaintance with the wonders of the heavens by the idea that these are only disclosed to the possessors of large and costly instruments. In reality there is probably no science which offers to those whose opportunities and means of observation are restricted greater stores of knowledge and pleasure than astronomy; and the possibility of that quickening of interest which can only be gained by practical study is, in these days, denied to very few indeed. Accordingly, I have endeavoured, while recounting the great triumphs of astronomical discovery, to give some practical help to those who are inclined to the study of the heavens, but do not know how to begin. My excuse for venturing on such a task must be that, in the course of nearly twenty years [pg viii] of observation with telescopes of all sorts and sizes, I have made most of the mistakes against which others need to be warned. The book has no pretensions to being a complete manual; it is merely descriptive of things seen and learned. Nor has it any claim to originality. On the contrary, one of its chief purposes has been to gather into short compass the results of the work of others. I have therefore to acknowledge my indebtedness to other writers, and notably to Miss Agnes Clerke, Professor Young, Professor Newcomb, the late Rev. T. W. Webb, and Mr. W. F. Denning. I have also found much help in the Monthly Notices and Memoirs of the Royal Astronomical Society, and the Journal and Memoirs of the British Astronomical Association.