Søbarometret alle 3 Expeditionsaar. Naar Fartøjet havde 
inde hele sin Kul- og Vandbeholdning, var Barometrets 
Kapsel 1” over Hav-Niveauet. Eftersom disse Beholdninger 
forbrugtes, løftede Fartøjet sig indtil 0.”5 i Vandet. Ba- 
rometerkapselens Højde over Havfladen var saaledes gjen- 
nemsnitlig 1.”25, og Barometerhøjdens Reduction til Hav- 
fladen, der i Observationstabellerne er anbragt ved samme, 
er sat til + 0.7713. 
I 1876 havde Expeditionen paa Rejsen til og fra Is- 
land stadig meget uroligt Vejr. Barometret var under disse 
Omstændigheder vanskeligt at-observere, da det, navnlig 
naar Fartøjet satte, pumpede betydeligt. For at faa en 
brugbar Observation, maatte lagttageren passe paa at op- 
søge den højeste og laveste Stand under Pumpningen og 
tage Middel af disse. Denne Observationsmethode tog imid- 
lertid uforholdsmæssig lang Tid. At Observationerne dog 
have lykkets, derpaa tyder den regelmæssige Curve for den 
daglige Variation, som udkommer for 1876 og navnlig dennes 
Lighed med Curverne fra de to følgende Aar. 
Efter Expeditionens Tilbagekomst til Bergen i 1876 
sammenlignede jeg Søbarometret Adie 1493 med 2 Baro- 
metre, hvis Correctioner vare bestemte ved det meteorologiske 
Institut i Christiania. For det ene, Rejsebarometret Ne- 
gretti & Zambra No. 649, fandtes 1 Maj 1876 Correctionen 
= + 0.7718, September 21—30 Correctionen = + 0.”m12, 
Middel Corr. = + 0.7715. For det andet, Stationsbaro- 
meter Adie No. 1511, fandtes i Marts 1876 Correctionen 
— 0.7734. Tages Medium af disse 2 Barometre, corri- 
gerede med disse Correctioner, som Normal, give Sammen- 
ligningerne 1 Bergen, der udførtes paa Observatoriet, fol- 
gende Resultat. 
32 
(Fig. 4, a) the marine barometer retained on each of the 
three cruises of the Expedition. When the vessel had 
taken in her full complement of coal and water, the cistern 
of the barometer reached 1” above the sea-level. As the 
said complement diminished, the vessel gradually rose 0."5 
in the water. The height of the cistern of the barometer 
above the sea-level was accordingly on an average 1.”25, 
and the reduction of the observations of the barometer to 
the sea-surface is put at + 0.713. The observations 
given in the Tables include this correction. 
In 1876, the Expedition encountered exceedingly boi- 
sterous weather on the whole of the passage to and from 
Iceland. Hence the barometer under these circumstances 
was difficult to observe, since, in particular when the vessel 
pitched, it pumped considerably. In order to obtain a 
trustworthy observation, the highest and lowest extremes 
reached during the pumping had to be noted as carefully 
as possible, and the mean of the two taken. This mode 
of observation was, however, necessarily troublesome and pro- 
tracted. That the observations notwithstanding proved suc- 
cessful, may be inferred from the regularity of the curve 
resulting for the diurnal variation for 1876, and more 
especially from its conformity with the curves constructed 
for the two following years. , 
After the return of the Expedition to Bergen in 1876, 
I compared the marine barometer Adie No. 1493 with two 
barometers for which the corrections had been determined at 
the Meteorological Institute in Christiania. For one of these 
instruments. a mountain barometer, Negretti & Zambra No. 
649, the correction in May 1876 was found = + 0.”"[8, 
in September (21—30) = + 0.””12; the mean correction 
being = + 0.”m15. For the other instrument, a station 
barometer, Adie No. 1511, the correction in March 1876 
was found = — 0.”"34. Taking the mean of these two 
barometers, reduced with the said corrections, the com- 
parisons in Bergen, made at the Observatory, gave the fol- 
lowing result: — 
for Adie 1493. 
1876. Lufttryk (Pressure). Corr. 
Sept. 4 135.40" = 04 
a § 740.3 — 0.60 Bar. sterkt faldende (Bar. falling rapidly). 
po 742.6 — 0.45 
» 8 Taba = OJ I 
Middel (Mean) 745.7 — 0.44 (MIN = sp 0097) 
I Middelet er Observationen den 5te September givet 
halv Vægt. 
Søbarometrets Correction har saaledes holdt sig con- 
stant fra Rejsens Begyndelse til dens Ende i 1876. Sam- 
menligningerne i September vise ikke synderlig sterke Tegn 
til, at Correctionen skulde være mindre ved 740”” end ved 
755"”.  Barometerhøjder under 750”” forekomme ikke hyp- 
pigt i 1876. 
For the mean, the observation taken on the 5th of 
September has been given half weight. 
The correction of the marine barometer had accor- 
dingly kept unchanged from the commencement of the cruise 
in 1876 to its termination. The comparisons undertaken 
in September do not afford particularly forcible indications 
that the correction for 740”” should be less than for 755”. 
Readings of the barometer under 750”” did not occur fre- 
quently in 1876. 
