5° 



H. MOHN. M.-N. Kl. 



o" and + o''.4 at — 20°. The zero point was verified when it commenced 

 to be read for the daily observations. The corrections for both thermo- 

 meters have been inter- and extra-polated from the corrections at 0° 

 and — 20O. 



2. Pressure of the Air. 



On the excursion in September the pressure was observed with the 

 aneroid No. 3, reading inches. Comparisons with the mercury barometer 

 at Framheim made before and after the excursion, gave a mean correction 

 of + 6.3 m.m. ± 0.3 m.m. 



On the journe}' to the Pole and back, the pressure was observed 

 with the aneroid No. 4, reading inches. The comparisons with the mer- 

 cury barometer at Framheim gave, in October, 



At 720 730 740 750 m.m. 



Corn — 1.3 — 1.5 — 1.7 — 2.0 m.m. sHghtly smoothed. 



On the journey to the Pole, Capt. Amundsen carried with him two 

 Hypsometers, No. 25249 and No. 25250, made by Cary, London, and 

 divided into degrees Fahrenheit. They were a gift from Sir Ernest 

 Shackleton and proved extremely useful for the success of the scientific 

 work of the Expedition. The Certificates of examination from the Natio- 

 nal Physical Laboratory, Teddington, dated April, 191 o, give the following 

 corrections. 



At 190" 195*^ 200" 205"^ 212OF. 



No. 49 Corr. -\- 0^.3 -\- 0^.3 + 0O.3 + 0O.4 + 0O.3 F. 



No- 50 . 4- 0O.5 ^ 0O.5 + 0O.4 + 0O.5 + 0O.5 F. 



The two hypsometers and the aneroid were read simultaneously by 

 Capt. Amundsen from the 6*^ November to the 17*^ December, 28 times. 

 Applying the corrections to the readings of the hypsnmeters, I found that 

 the corrected values of their boiling-points agreed perfectly in 14 instances, 

 within qO.i. F. in 6 instances, and within o''.2 F. in 8 instances. In the 

 last cases the mean has been taken. The following Table shows the 

 boiling-point T in C", the corresponding pressure of the air B in milli- 

 metresS the readings of the aneroid A converted into millimetres, and the 

 resulting correction of the aneroid in millimetres. 



1 WiEBE, Tafeln über die Spannkraft des Wasserdampfes. 



