76 Master Minds of Modern Science 



two hundred miles eastward. Professor David wished 

 actually to reach the Magnetic Polar point itself, and so 

 to check these observations further, thus for the first 

 time providing mariners with exact information concern- 

 ing the point to which their compasses swung south of 

 the equator. 



There was also another reason in Professor David's mind 

 when he started out on the long trek on October 5th, 

 1908, accompanied by Dr Mawson and Dr Forbes Mac- 

 kay. He wanted to take possession of the South Mag- 

 netic Pole in the name of Britain, and hoist the Union 

 Jack there. 



It was a formidable task, for all three men had to drag 

 behind their backs over two hundred and forty pounds. 

 And remember that the Professor was fifty years of age ! 

 No wonder that several members of the expedition felt 

 that he was taking an undue risk — that he should have 

 been content to advise the others, and remain at the base. 



For days and weeks they sledged steadily on — up the 

 glaciers and on to the plateau, 7000 feet above sea-level. 

 Several times they narrowly escaped being hurled to death 

 down crevasses which opened in the ice at their feet. But 

 good fortune was with them, and on January 15th, one 

 hundred and two days out, observations taken by Mawson 

 showed that they were nearing their objective. 



The observations made with their compasses that day 

 showed the angle to be only fifteen minutes off the ver- 

 tical, the dip being 89 45', whereas at the Magnetic Pole 

 itself the dip is 90 . The same evening it was 89 48'. 



It should be explained that the compass familiar to 

 everybody is mounted on a vertical pivot and can there- 

 fore swing in a horizontal direction only. These com- 

 passes are controlled by magnetic force coming from the 

 earth at the point of attraction, and if they were taken 

 to the Magnetic Poles, where the magnetic force is 

 vertical, they would be unaffected and useless. 



