54 



H. MOHN. M.-N. Kl. 



I have tried this metliod for the stations from Framheim to 80'^ of 

 latitude. Farther South the distance from Framheim was too great to 

 allow of the construction of isobaric charts, the distribution of pressure 

 being too irregular. 



The next rational method for finding the heights above sea-level of 

 the stations of observation is to proceed from Framheim, the only station 

 of which the height is known, and run a barometrical levelling from 

 station to station. The levelling-staff of the ordinary spirit levelHng is 

 replaced by the barometrical scale. The difference of pressure between 

 two consecutive stations allows of the computation of their difference of 

 height. By adding the results for the consecutive steps, we can find the 

 height of the stations proceeding from Framheim to the Pole. 



The observations employed for computing the differences of height 

 are always those made immediately before the starting from one station, 

 and immediately after the stop at the following station. This is the nearest 

 approximation to simultaneous observations. 



Observations of pressure and temperature were made on the journey 

 both to and from the Pole. But it was not generally at the same places 

 that the observations were made on the two journeys. It was therefore 

 obliged to proceed in the following manner. Starting from Framheim, I 

 took the sum of the heights computed from observations forwards and the 

 sum of the heights computed from observations backwards till I arrived at 

 a station visited on both journe3's. Of these sums I took the mean. Starting 

 from this mean I went in the same manner to the next double station, and 

 so on to the Pole. 



The height of the stations where onl}' one set of observations had 

 been made, have been found by interpolation. If the height of such a 

 station at the latitude 4 has been found to be I1.2, and the height at the 

 preceeding and following latitudes on the opposite track /] and /3 has been 

 found to be h^ and //3 the corresponding resulting //o' for lat. 4 has been 

 computed b\' interpolation. Then \ {/i-, -\- h./) has been taken as the most 

 probable height of the Station. 



The heights of the stations from Framheim to 80*^ lat. have been 

 computed by both methods, and the mean taken as definitive. 



The formula which I have employed for the calculation of the differences 

 of height is: 



The height d/i of a column of air corresponding to a pressure of 

 (fb is: 



dh metre = \ ■ '- ■ -'-- • ^- db mm. 

 d 273 b g 



