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10
Da en Sammenligning den 12te Juni mellem den nye
Yindmaaler og den ældre gav den første en
Frictionscoeffi-cient af 1.4, har jeg for 1877 regnet med Coefficienten
+ 1.6.
1878.
A comparison, on the 12th of June, between the new
and the old anemometers, having indicated according to
the latter, a friction-coefficient of 1.4, I computed for 1877
with the friction-coefficient 1.6.
1878.
L Vind maaler. Log. Anemometer.
Datum. Kvartmil i Timen. Meter pr. Secund. Meter pr. Secund. [-Frictions-!-] {+Frictions- !+} Coefficient Date. Naut. Miles 1 Metres an Hour. per Second. Metres per Second. [-Friction-Coefficient.-] {+Friction- Coefficient.+}
Juni i8 7.1 3.7 2.55 -f 1.15
Juli 5 6.7 I 3.5 2.3 1.2
„ 70 3.6 2.4 1.2
„ 20 7.0 ! 3.6 2.4 1.2 .
„ „ 7.0 3.6 2.35 J.25
Aug. 30 6.5 3.4_2-45 Q-95
Middel..............+ 1.16
For 1878 har jeg antaget Coefficienten til + 1.2.
Dersom man før Registreringen stillede Viseren paa
det Tal, der angiver Frictionscoefficienten, vilde man efter
30 Secunders Registrering kunne aflæse directe Vindens
Hastighed i Meter pr. Secund. Paa vor Expedition
stilledes altid Viseren paa 0, da det paa Forhaand ikke kunde
garanteres, at Frictionscoefficienten holdt sig constant.
Skibets Kurs observeredes efter det samme Compas
som Vindens Retning og noteredes paa hele Grader.
Com-passets Deviation var altid nøje kjendt, efter de Iagttagelser
og Beregninger, som vare udførte af Captein Wille. Skibet
svingedes for Deviation i 1876 i Husø, ved Sognefjordens
Munding, i 1877 i Husø før Rejsens Begyndelse og i
Vestfjorden ved dens Slutning, i 1878 i Bergen, udenfor Vardø,
udenfor Hammerfest, ved Beeren Eiland, i Grønlandshavet,
ved Spidsbergens Sydkap og under Grønlandsisen Vest for
Spidsbergen.
Da Deviationens Størrelse var merkelig afhængig af
den geografiske Position i de Farvande, som Expeditionen
besøgte i 1878, var det nødvendigt ved Beregningen af
Vindens og Skibets Retning at tage Hensyn hertil. Af
Capt. Wille modtog jeg til dette Øjemed to af ham
udarbejdede grafiske Fremstillinger, nemlig 1° et Kart over den
i 1878 gjennemsejlede Del af Havet, paa hvilket var
optrukket Linier for ligestore Værdier af den i Formelen for
Compassets Deviation benævnte Coefficient B, der
omtrentlig angiver Deviationens Maximumsværdi, og 2° en Række
Deviationscurver (Argument: anlagt Kurs efter Compasset,
Function: Deviationens Størrelse i Grader) betegnede med
forskjellige Farver og ordnede paa samme Plade med
fælles Kursargument samt optrukne for forskjellige
bestemte Værdier af Coefficienten B. For enhver
paa-værende Plads kunde saaledes af Kartet No. 1 udtages
Værdien af B og med denne samt anlagt Kurs pr.
Compas kunde af No. 2 udtages den tilsvarende Værdi af
June 18 7.1 3.7 2.55 + 1.15
July 5 6.7 3.5 2.3 1.2
„ „ 7.0 3.6 2.4 1.2
„ 20 7.0 3.6 2.4 1.2
„ 7-0 3-6 2.35 1.25
Aug. 30 6.5 3.4 2-45 i Q-95
Mean...............+ 1.16
•
For 1878, I adopted the coefficient -(- 1.2.
If, before registration, the index were adjusted to the
cipher indicating the friction-coefficient, the observer, after
registering 30 seconds, could read off at once the velocity
of the wind in metres per second. On our Expedition,
however, the index was always adjusted to zero, since
beforehand it is impossible to tell with certainty whether the
friction-coefficient will remain unchanged.
The Ship’s Course was observed by the same compass
as the direction of the wind, and noted in whole degrees.
The deviation of the compass was at all times accurately
known, from Captain Wille’s observations and computations.
In 1876, the ship was swung for deviation at Husø, at the
mouth of the Sognefjord; in 1877, at Husø, before the
commencement of the cruise, and in the Vestfjord at its
termination; in 1878, at Bergen; off Vardø; off
Hammerfest; at Beeren Eiland; in the Greenland Sea; off Cape
South, Spitzbergen; and at the Greenland ice barrier, west
of Spitzbergen.
The amount of deviation being perceptibly dependent
on the geographical position of the vessel in the tracts of
ocean visited by the Expedition in 1878, it was necessary
when computing the direction of the wind and of the ship, to
take this circumstance into account. Captain Wille
provided me with two diagrammatic representations, which he
had specially prepared for that purpose, viz. 1, a chart of
the tract of ocean explored by the Expedition in 1878, on
which were lines indicating equal values of the coefficient B
in the formula for the deviation of the compass, which
coefficient approximates the maximum value of the deviation; and
2, a series of deviation-curves (abscissae: course by compass;
ordinates: deviation expressed in degrees) marked with
different colours and arranged on the same Plate, according
to common course-abscissæ, for different definite values of
the coefficient B. Hence, for each position of the ship,
the value of B could be found on chart 1, and, with
this value and the course by compass, the corresponding
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