ΤΟ WILLIAM HUGGINS, D.C.L. LL.D. F.R.S. -THE HERSCHEL OF THE SPECTROSCOPE IN RECOGNITION OF THOSE LABOURS BY WHICH THE WHOLE ASPECT OF MODERN ASTRONOMY HAS BEEN MODIFIED This Work is Dedicated BY THE AUTHOR. PREFACE TO THE SECOND EDITION. THE FAVOURABLE RECEPTION accorded to the first edition of this treatise (two thousand copies of which were sold during less than a year from the date of publication) encourages me to hope that the work has been found a useful compendium of what is known or may be surmised respecting the great ruling luminary of our system. The present edition has been completely revised, and in some important respects modified. Several new illustrations, for which I am indebted to Mr. Brothers of Manchester, and to Professor Young, Mr. Willard, and Mr. Knight, of America, have been added, as well as an account and analysis of the observations made during the eclipse of December 1870. Some of the modifications in the present edition are due to suggestions made in reviews; and in acknowledging this obligation, I cannot refrain from expressing my sense of the kindly tone in which, with scarce an exception, the present work has been treated by reviewers. It may be a dangerous admission to make, but it is simply the truth that their mildly expressed censures or corrections have often seemed to me better merited than their very generous commendations. Yet I have occasion to defend myself from a most serious charge occurring in a review, of which I certainly had no other reason to complain, and in a journal whose general fairness is beyond suspicion. It was remarked in the Athenæum' that I show myself in this work a little too niggardly in claiming every scrap of theory to which I may be entitled.' As I was not conscious of any passages deserving this rebuke, while I was exceedingly anxious to remove such blemishes if they existed, I sought for further information. The editor of the Athenæum ' pointed out in reply that the sentence involved no reference to the justice of the reclamations.' But I pressed for instances of niggardliness, or even of any reclamation of a scrap of theory, for I knew of none throughout the book, nor could I remember a single instance in which I had had occasion there or elsewhere to reclaim a scrap of theory' from any fellow-worker in science. I was met with the rejoinder that the criticism was based on the general tone of the volume, not on any special instances of reclamation! If the criticism had not been specially limited to scraps of theory,' and explained by the |