228 H. Hansen. 
Where B, = Pressure of the atmosphere on the lowest placed station. 
B = Pressure of the atmosphere on the highest placed station. 
6 = Mean temperature of the air column between the two 
stations. 
e = Mean pressure of aqueous vapours in the air column. 
b = Mean barometric pressure of the air column. 
ф = the latitude of the station. 
h, = the height of the lowest placed station. 
R = the mean radio of the earth. 
If this formula is used for figuring out the elevation on basis of 
Captain MIKKELSEN’s and Lieutenant Laus’s observations on the pres- 
sure of the atmosphere, it is possible to omit the three last factors 
ofthe formula, as these, on account of the high geographical latitude 
(above 75°) and the comparatively small elevations here, have no in- 
fluence on the ultimate results. 
With the 3 last factors out of the reckoning, the formula then 
reads as follows: 
Z — 18400 (log By —log В) (1 + 0.00367 6) (1 + 0.378 | 
In this, the e — the mean pressure of aqueous vapours in the air 
column — is unknown, as the vapour pressure was not at all ascertained 
during the expedition. Its influence on figuring out the elevations is 
however exceedingly small. With a temperature of f. inst. + 20° and 
an elevation above the sea level of 1000 metres, the factor |1 + 0.378 =| 
would only change the result with 1/, metre, even if the air was saturated 
with vapours. 
If this factor is then let out of the reckoning all together, the formula 
will be reduced to: 
Z = 18400 (log В, —log В) (1 + 0.00367 8) 
and the elevations found in table 4 are computed according to this. 
In order to be able to figure out the elevation of a certain place 
according to above simplified formula, it is then necessary to know 
the barometer-reading at the spot, B., 
the corresponding barometer-reading, By, at sea level in the vertical 
of the spot and 
the mean temperature, 9, of the vertical air column. 
Are these factors known, the figuring out of the elevation is com- 
paratively easy to make. | 
For instance: 
В = 691.0mm., B, = 765.1 mm., —————~-———_— 
Z = 18400 (log 765.1 — log 691.0) (1 ~ 0.08074) = 748 metres. 
