136 



S. L. Pen field — Stereographic Project 



ion. 



A line plotted on a sphere so as to intersect all meridians 

 at the same angle, and which appears as a straight line 

 on a Mercator's projection, is known as a rhumb-line, and 

 sailing with the same compass bearings from the place of 

 departure to the place of destination is known as rhumb- 

 sailing. A rhumb-line intersecting the meridians at an 



oblique angle (the condition which almost always comes into 

 consideration) gives, when plotted on a sphere, a spiral curve 

 with complex mathematical relations, known as a loxodromic 

 curve. Figure 30 represents the meridians and parallels of a 

 hemisphere in stereographic projection, and two possible sail- 

 ing routes, from Cape Flattery, 124° 45' W., 48° 30' K, the 

 extreme northwestern point of the State of Washington, to 

 the entrance of Bass Strait, 148° E., 40° S., leading to Mel- 

 bourne, South Australia. The shortest route is the great circle 

 x a?, which, if followed, necessitates a slight change of compass 



