Two objects have been kept in view in preparing this little book. One was to condense those facts and laws of the science which are of most interest and importance to the general intelligent public within so small a compass as not to make a very serious addition to the curriculum of the high school or college. The other was so to present the subject that as little formal mathematics as possible should be noces sary to its mastery. Of the first object little need be said. The typical person constantly kept in mind has been the inquiring layman seek ing to know something of the heavenly bodies and their rela tion to the earth, including such subjects of human interest as the changing seasons, the measure of time, and the varying aspects of the planets.