XX INTRODUCTION. 



Table 1 7. Inter conversion of nautical and statute miles. 



The nautical mile as defined by the U.S. Coast and Geodetic Survey 

 (Tables for a polyconic projection of maps. U.S. Coast and Geodetic Sur- 

 vey, Special Publication No. 5, page 4) is "A minute of arc of a great circle 

 of a sphere whose surface equals that of the Clarke representative spheroid 

 of 1866," and the value given is 1853.25 meters, or 6080.20 feet. 



Table 18. Continental measures of length with their metric and English 

 equivalents: 



This table gives a miscellaneous list of continental measures of length, 

 alphabetically arranged, with the name of the country to which they belong 

 and their metric and English equivalents. 



CONVERSION OF MEASURES OF TIME AND ANGLE. 



Table 19. Arc into time. 



I °= 4 m ; !'=4 S ; l"=^ 8 =o?o67. 



8 h i7 m i!6 4 7 



15' 



15" 



9.60 



O.IO 



124 15' 2 4 :; 7 



Table 21 . Days into decimals of a year and angle. 



The table gives for the beginning of each day the corresponding decimal 

 of the year to five places. Thus, at the epoch represented by the beginning 

 of the 15th day, the decimal of the year that has elapsed since January 1.0 



is computed from the fraction , . The corresponding value in angle 



3 6 5-25 

 obtained by multiplying this fraction by 360°, is given to the nearest minute. 



