vigelse af en enkelt Observation fra det normale Medium 
er + 197. Den absolute Maximumsafvigelse er 205. Ved 
Observation af Havoverfladens Temperatur i Sommermaa- 
nederne, reduceret til Midten af August, maa man altsaa 
i vort Nordhav være belavet paa at finde den indtil et Par 
Grader højere eller lavere end den normale. For at bringe 
den sandsynlige Fejl af Normalmediet ned til + 09.1 ud- 
fordres Observationer fra 81 Aar. 
Til Construction af Kartet for Havoverfladens normale 
Temperatur i Marts foreligger,: for Strækningen fra Nord- 
søen forbi Shetland til Jan Mayen og Grønlandshavet nor- 
denfor denne Ø, 19 Aars Observationer (1867—835) fra norske 
Sælfangere. Blandt disse have især været virksomme Cap- 
tejnerne Carsten Bruun, Jacob Melsom, Axel Kref- 
ting, L. Grønvold og L. H. Castberg, der have ind- 
sendt sine lagttagelser til det norske meteorologiske Institut. 
Disse Observationer har jeg, for Marts Maaned, da Varia- 
tionen er ringe, afsat uden Reduction til Midten af Maaneden, 
paa et Kart, og tegnet Isothermer efter dannede Gruppe- 
media. 
For at kunne fortsætte disse Isothermer op til Spids- 
bergen har jeg paa den ene Side benyttet de lagttagelser, 
der ere gjorte i Dybet i Magdalene Bay, Nordvest-Spids- 
bergen, og paa den anden Side de Iagttagelser, som gjordes 
under *Alberts” Rejse til Spidsbergen i November og De- 
cember 1872. 
I Dybet af Magdalene Bay fandt Charles Martins, 
Medlem af Expeditionen med “La Recherche”, i August 1839 
Temperaturer fra —1°.7 til —199"./ Sammesteds fandt jeg 
i August 1878 Temperaturer fra —1°.8 til —2°1. Disse 
lave Temperaturer maa hidrøre fra Vinterkulden 1 Over- 
fladen, og jeg setter derfor Temperaturen 1 den koldeste 
Maaned, Marts, ved Nordvest-Spidsbergen til —2°. 
Efter Meddelelse fra Capt. Carsten Bruun, der i 20 
Aar har drevet Sælfangst ved Jan Mayen, gaar den mid- 
lere Isgreendse (Pakisen) om Vinteren fra et Punkt 3° østen- 
for Jan Mayen mod NNE til 759 N. Br., 0° Længde, hvor 
den danner det saakaldte Is-Nes. Idet den her pludselig 
vender sig mod WNW, danner den en stor Bugt, der væ- 
sentlig hidrører fra vedholdende østlige Vinde. Den inderste 
Vig af denne Bugt ligger mellem 769 og 77° N. Br. og fra 
5° til 10° vestlig Længde. Bugtens nordlige Bred dannes 
af Isgrændsen, der løber mod ENE hen til Spidsbergen. 
Efter denne Isgrændse har jeg trukket Isothermen for —2° 
for Marts fra Jan Mayen til Nordvest-Spidsbergen. 
Paa Rejsen til Spidsbergen fandt Capt. Otto? den 
24. November 1872 i Sydvest for Spidsbergens Sydkap, 
1 Voyages en Scandinavie, en Laponie et au Spitzberg de la 
corvette La Recherche — Géographie physique, IL, p. 349. 
? Alberts Expedition til Spidsbergen i November og December 
1872 og dens videnskabelige Resultater. Christiania Videnskabs-Sel- 
skabs Forhandlinger for 1873. 
101 
imum-deviation of a single observation from the normal 
mean, is + 1°.7. The absolute maximum-deviation is 2°.5. 
When measuring the temperature of the sea-surface during 
the summer-months, reduced! to the middle of August, we 
must, therefore, be prepared to find it in the Norwegian Sea 
some two or three degrees higher or lower than the normal. 
In order to bring down the probable error to + 0°.1, obser- 
vations are required extending over a period of 81 years. 
For constructing a map that shows the normal temper- 
ature of the sea-surface in March, we have for the tract 
from the North Sea past Shetland to Jan Mayen and the 
Greenland Sea north of the latter island, 19 year’s observations 
(1867— 1885), furnished by Norwegian sealers. Amongst 
the captains distinguished as specially energetic, we can men- 
tion Carsten Bruun, Jacob Melsom, Axel Krefting, L. Grøn- 
vold, and L. H. Castberg, who sent in their journals to the Nor- 
wegian Meteorological Institute. These observations I have 
set down for the month of March, without reduction to the 
middle of that month, the variation being inconsiderable, 
on a map, and have drawn the isotherms from the means 
of collected groups. 
to 
Spitzbergen, I have, on the one hand, made use of the ob- 
servations taken throughout the depths of Magdalena Bay, 
north-west coast of Spitzbergen, and, on the other, those 
made during the cruise of the “Albert” to Spitzbergen, in 
November and December 1572. 
In the depths of Magdalena Bay, M. Charles Martins, 
“Tia Recherche,” found, 
during the month of August 1839, a temperature ranging 
from —1°.7 to —1°.9.! Throughout the same locality, in 
August 1878, I registered a 
—1°.8 to —2°.1. These low temperatures must obviously 
originate in the winter-cold of the surface; and hence I 
put the temperature on the north-west coast of Spitzbergen 
during March, the coldest month of the year, at —2°. 
According to a statement communicated by Capt. Car- 
sten Bruun, who, during the space of 20 years, has been 
engaged in the seal-fishery off Jan-Mayen, the mean ice-limit 
In order extend these isotherms as far north as 
member of the Expedition with 
emperature varying fron 
ten t varying from 
(of the pack) im winter extends froma point 3° east of Jan 
Mayen towards the NNE, as far as lat. 75° N, long. 0°, 
where it forms the so-called ice-cape. 
suddenly towards the WNW, it constitutes a large bay, 
chiefly the result of continuous easterly winds. The inmost 
ereek of this bay lies between lat. 76° and lat. 77° N and 
long. 5° to long. 10° W. The northern shore of the bay is 
formed by the ice-limit, which, passing ENE, reaches up to 
Spitzbergen. Along the tracts of the ice-limit, I have drawn 
the isotherm for —2°, in March, from Jan-Mayen to the 
north-west coast of Spitzbergen. 
On his voyage to Spitzbergen, Capt. Otto? found on 
the 24th of November 1872, to the south-west of South 
Here, diverging 
1 Voyages en Scandinavie, en Laponie et au Spitzberg de la 
corvette La Recherche — Géographie physique, I, p. 349. 
* Petermanns Geographische Mittheilungen f. 1873. 
Highways, June 1873, p. 104. 
Ocean 
\ 
