GENERAL DESCRIPTION OF THE MOON. « 



By N. S. Shaler, 

 Professor, Harvard University. 



Althoug-h the moon has been the most .studied of all celestial -objects, 

 few persons except astronomers have a clear idea of even the general 

 results which have been derived from the vast body of observations 

 that have been made upon it. For this reason it appears desirable to 

 preface the account of the special inquiries which are set forth in the 

 following pages by a statement of what is known concerning- this near- 

 est neighbor of our earth. This account will necessarily be limited to 

 the facts which can be set forth in other than mathematical form; 

 fortunately these include all that the reader needs to have in mind in 

 order to obtain a fairly clear understanding of the questions which are 

 to be discussed. 



The history of primitive astronomy shows that the moon, of all 

 celestial objects, from the beginning of man's intellectual development 

 has been the most closely ol)served. Although the sun was doubtless 

 recognized by the lowliest man as the most important feature of the 

 heaveas, as the giver of life, the conditions under which it is seen, 

 especially its blinding light, long made any extended study of it 

 impossible. So, except for the very evident changes of its course 

 across the sky and the consequent succession of the seasons, little was 

 known of the solar center two hundred years ago, and, save its approx- 

 imate distance from the earth, its mass, and its general relations to the 

 planets, not much knowledge of it was gained until the last century. 

 On the other hand, the moon, ))ecause of its nearness, being only about 

 one four-hundredth part as remote from the earth as the sun, has in a 

 noteworthy way entered into the records of men. Its relatively short 

 period of change and the very pronounced character of its alterations 

 made it the tirst index of time beyond the round of the day. It is 

 evident, indeed, that as soon as men l)eg-an to reckon time they used 

 the lunar month to make their talh , rather than that of the solar year. 



a Introductorjr chapter from A Comparison of the Features of the Earth and the 

 Moon, by Prof. N. S. Shaler, Bmithsoiiian Contributions to Knowledge, Vol. XXXIV 

 (No. 1438), 1903. Quarto, pp. 78, with 25 plates. 



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