THE TERRA NOVA GOES SOUTH 



5i 



this parallel of latitude. To do this we require the longitude. 

 All that is necessary is to find the difference in time between 

 that at Greenwich and the local time (as shown by the sun) 

 in the aforementioned illimitable plain. A chronometer (a 

 watch with a special compensation for temperature changes) 



Vole 



Sun 



/ s 



Required / ,0 ? 

 G't/en /So* 3 ond 



Observed /s? H 



£<}ijATort 



Latitude. 



Required /£££ 

 Given &Z *>"** PS 



Observed Sz 



£. aoA-ro** 



Longitude. 

 The celestial triangle is shaded. The earth is to be considered a point. 



gives him Greenwich time ; and the problem is to get the 

 exact local time and to transform the hours into degrees by 

 multiplying by fifteen (24 hours = 360 ). Our next diagram 

 is on a larger scale. We have increased our spherical surface 

 so that the sun lies on its surface at S. A vertical line, OZ, 



