A NEW ASTRONOMY, $1.30 



By DAVID TODD, M. A., Ph. D., Professor of Astrono- 

 my and Navigation and Director of the Observatory, 

 Amherst College. 



\ STRONOMYis here presented as preeminently a science 

 ^^\. of observation. More of thinking than of memorizing 

 is required in its study, and greater emphasis is laid on 

 the physical than on the mathematical aspects of the science. 

 As in physics and chemistry, the fundamental principles are 

 connected with tangible, familiar objects, and the student is 

 shown how he can readily make apparatus to illustrate them. 

 In order to secure the fullest educational value, astronomy is 

 regarded as an interrrelated series of philosophic principles. 



MATHEMATICAL GEOGRA- 

 PHY, ^i.oo 



By WILLIS E. JOHNSON, Ph. B., Vice-President and 

 Professor of Geography and Social Sciences, Northern 

 Normal and Industrial School, Aberdeen, South Dakota. 



THIS work explains with great clearness and thoroughness 

 that portion of the subject which not only is most diffi- 

 cult to understand, but also underlies and gives meaning 

 to all geographical knowledge. A vast number of facts which 

 are much inquired about, but little known, are taken up 

 and explained. Simple formulas are given so that a student 

 unacquainted with geometry or trigonometry may calculate 

 the heights and distances of objects, the latitude and longitude 

 of ^ place, the amount any body is lightened by the centri- 

 fugal force due to rotation, the deviation of a plumb-line from 

 a true vertical, etc. 



AMERICAN BOOK COMPANY 



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