Geographical Maps and Sailing Charts. 



261 



miles. It takes but a few minutes to make such a series of 

 measurements, and the results are accurate. Moreover the 

 method is so simple that any one could easily be taught to use 

 the protractors and thus learn an important lesson in mathe- 

 matical geography. 



Figure 12 represents the method of solving the following 

 problem : To find the distances from New York to Buffalo, 



Stereographic Protractor adjusted for measuring from New York to Buffalo, 



Chicago, Denver, San Francisco and Manila. Small circles 



only are printed on the protractor. 



Chicago, Denver, San Francisco, Honolulu and Manila, the 

 latitudes and longitudes of the places being given. The 

 places were located on a 14 cm diameter, engine divided plate 

 from the following data : 



San 

 Denver. Francisco. Honolulu. Manila. 



39° 45' 37° 47' 21° 20' 14° 36' 

 105 122 25 157 55 239 8 



74 00 74 00 74 00 74 00 



New York. 



Buffalo. 



Chicago. 



fc. 40° 43' N. 



42° 53' 



41° 50' 



ag. 74 00 W. 



78 55 



87 34 



ng. of New York 



74 00 



74 00 



Gg. W. from 







New York 



4 55 



13 34 



31 00 48 25 83 55 165 8 



Am. Jour. Sci. — Fourth Series, Vol. XIII, No. 76. — April, 1902. 

 18 



