THE HEIGHT OF THE SOUTH POLE. 



233 



on January 9th. Thj mean pressure at Cape Evans and Framheim on these days was the 



following ; — 



Table 153. 



Pressure charuje at sea-level. 



Date. 



Cape Evans. 



November 15th 

 December 17th 

 January 9th . 



29-58 

 29-80 

 29-12 



Framheim. 



29-54 

 29-76 

 29-20 



Mean. 



29-56 

 29-78 

 29-16 



Change. 



+ ■22 



It will be noticed that the general pressure rose as Amundsen went from the Barrier 

 to the Pole and fell as he returned, both these changes would make the difference in height 

 b^ween the Barrier and the Pole appe'ar less than it really was. The mean change in 

 pressure was -42 inches. This is equivalent to a change of height of approximately 400 feet, 

 by which amount the height of the Pole would be underestimated. Even with this correction, 

 Mohn's determination of the height of the Pole would only be about 8,500 feet, leaving another 

 500 feet to be accounted for. I have tried to apply the method used in reducing Scott's observa- 

 tions to those taken by Amundsen but have not been successful, as Amimdsen's marches 

 on the plateau were more irregular than those of Scott and his track on the plateau was 

 much less level. I have, however, been able to use Amundsen's observations to show that the 

 height of the Pole determined from Scott's observations is not in error by 200 feet. 



°it seemed very desirable in the first place to be assured that there was no radical error 

 in either of the barometers. This seemed very unlikely for Amundsen's barometer was fre- 

 quently checked by two hypsometers while on the plateau and Scott's barometer was also 

 checked by a hypsometer a short time before the plateau was reached. Luckily a direct 

 comparison is possible which shows that the barometers were reading with the accuracy 

 to be expected under such conditions. On December 31st, 1911, Amundsen was at 87° 9' S., 

 167" 7' W. and Scott was at 86" 56' S., 165" 6' E., thus they were approximately only 

 87 geographical miles apart. According to Mohn's calculation Amundsen was then 1 metre 

 below the elevation of the Pole; while Scott was, according to the above calculations, 320 

 feet above the Pole. As the positions were so near to the Pole, both these differences may be 

 accepted quite independently of the actual height assigned to the Pole. 



Thus on this day Amundsen was 323 feet below Scott. The pressure and temperature 

 recorded were the following: Amundsen 6 p.m., barometer 20-67;", temperature -2°F. ; Scott 

 2 p M barometer 20-28", temperature - 10-5°F. If the difference of height is correct Scott's 

 barometer should have read -27" below Amundsen's while we see that it was -39" lower. Thus 

 the barometers differ by only -12" from their true relative readings. Part of this difference 

 may be due to the fact that the barometers were not read simultaneously, part to the distance 

 between the two observers, and part to errors m the determmation of their relative^ heights. 

 In any case it is quite obvious that there was no difference in the barometers sufficient to 

 account for the discordant determinations of the height of the Pole. 



Delermmcition of the height of the Pole hy simultaneous observations of Amundsen's Barometer 

 ai the Pole and or^e on the Barrier near to the foot of the hills. -Amm^dsen was at, or within 

 six miles of, the Pole throughout January 16th, 17th and 18th. The mean P-ssure and 

 temperature observed by him during these three days (three observations each day were 20-48 

 and -7"F At the s^me time Meares mth Captain Scott's dogs was near to the toot ot the 

 Beardmore in 82" S. His mean pressure and temperature for the same days (also three 



