300 ANNUAL &EPOB.T SMITHSONIAN INSTITUTION, 1911. 



the world map on the scale of 1 : 1,000,000. As the scale is five times 

 as large, each of these sheets wall be of approximately the same dimen- 

 sions as the corresponding sheet of the 1: 1,000,000 map. 



It is necessary, however, to introduce a more simple method of 

 notation. It is customary to distinguish between longitudes east 

 and west of the initial meridian and between latitudes north and 

 south of the Equator. The nomenclature of the latitude and longi- 

 tude therefore changes as one passes across either of these lines of 

 origin. In other words, degrees of longitude increase to the right 

 cr left from the initial meridian and degrees of latitude increase both 

 north and south from the Equator. This notation is apt to cause 

 trouble. 



In order to overcome this disadvantage, the committee at my sug- 

 gestion has decided to number the longitudes from 0° to 360° in an 

 easterly direction, commencing from longitude 180° east or west 

 of Greenwich, and to substitude for latitudes polar distances meas- 

 ured from the South Pole and reading from 0° to 180°. Tins is done 

 in order that in the Northern Hemisphere, in which are situated most 

 of the inhabited countries, the number may increase as usual from the 

 Equator northward. Moreover, in the Northern Hemisphere the 

 units of degrees would be the same for a south polar distance as for 

 the corresponding latitude. The units of the longitude thus adopted 

 will be the same, between 180° and 360°, as the} 7- are now for longi- 

 tudes east of Greenwich. The tens of degrees, in the case of south 

 polar distances, will be increased by 9 units, and in the case of longi- 

 tudes east of Greenwich by 18 units. 



In the Southern Hemisphere the polar distances will be the com- 

 plements of the corresponding latitudes, and in the hemisphere 

 extending from 0° to 180° of longitude the new longitudes of places 

 will be the supplements of the present longitudes west of Greenwich. 

 In addition to the usual notations, these new ones should be printed 

 on the world map and on the index diagram, figure 1 . 



Each sheet of the air map will bear the name of the most important 

 locality on the area covered by it and shall be numbered by the 

 coordinates of its southwestern corner. This number shows the 

 number of degrees of longitude and south polar distances in the 

 coordinates of any point in the sheet, and in order to obtain the com- 

 plete coordinates of any given point it will be sufficient to add to these 

 figures the tenths of degrees or minutes obtained from the marginal 

 scales. 



The air map will be constructed on the same modified polyconic 

 projection as that used for the world map. Each sheet shall be 56 

 centimeters, or 22 inches, high and from 41 centimeters to 34 centi- 

 meters broad (in France) . The corresponding breadth near London 

 would be 12 inches. Each sheet in France would therefore cover an 



