PREFACE.

The Lectures contained in this volume have been delivered•at Gresham College during the last two years. In responseto various requests, and by the kind and liberal assistance ofthe Gresham Committee of the City of London , to whom theauthor desires to tender his grateful thanks, they are nowpublished.

In the description of the Planets and Satellites whichthey contain, such information as may he found in almostevery astronomical text-book is briefly recapitulated; thatwhich is less familiar, or of recent announcement, is discussedmore fully. In the case of the Sun and Moon it has only beenpossible to mention a few points of special interest. Thosewho desire fuller information may consult the larger worksof Professor Young, Mr. Proctor, and the late Padre Secchi,upon the Sun; of Mr. Xeison, Mr. Proctor, and others, uponthe Moon . The time and space at the author’s disposal haveprevented him from making more than a passing reference tothe cometary and meteoric members of the Solar System .

A Gresham Lectureship only provides for the employment•of a limited amount of time in the duties of the office. It isextremely difficult for one who holds it to maintain a satis-factory acquaintance, amidst the press of other work, withthe vast range and the startlingly rapid progress of such asubject as Astronomy , for the study of which the longest