Chapter I: Preface

The rapid progress of discovery in the zone of minor planets, the anomalous forms and positions of their orbits, the small size as well as the great number of these telescopic bodies, and their peculiar relations to Jupiter, the massive planet next exterior,--all entitle this part of the system to more particular consideration than it has hitherto received. The following essay is designed, therefore, to supply an obvious want. Its results are given in some detail up to the date of publication. Part I. presents in a popular form the leading historical facts as to the discovery of Ceres, Pallas, Juno, Vesta, and Astræa; a tabular statement of the dates and places of discovery for the entire group; a list of the names of discoverers, with the number of minor planets detected by each; and a table of the principal elements so far as computed.

In Part II. this descriptive summary is followed by questions relating to the origin of the cluster; the elimination of members from particular parts; the eccentricities and inclinations of the orbits; and the relation of the zone to comets of short period. The elements are those given in the Paris _Annuaire_ for 1887, or in recent numbers of the _Circular zum Berliner Astronomischen Jahrbuch_.

DANIEL KIRKWOOD.

BLOOMINGTON, INDIANA, November, 1887.

CONTENTS.

PART I. PAGE

PLANETARY DISCOVERIES BEFORE THE ASTEROIDS WERE KNOWN 9

DISCOVERY OF THE FIRST ASTEROIDS 11

TABLE I.--ASTEROIDS IN THE ORDER OF THEIR DISCOVERY 17

NUMBERS FOUND BY THE RESPECTIVE DISCOVERERS 23

NUMBERS DISCOVERED IN THE DIFFERENT MONTHS 25

MODE OF DISCOVERY 25

NAMES AND SYMBOLS 25

MAGNITUDES OF THE ASTEROIDS 26

ORBITS OF THE ASTEROIDS 28

TABLE II.--ELEMENTS OF THE ASTEROIDS 29