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ombord med Kronometerstanden 15"’ 18/8. Elter
Verifikationen den lode i Hammerfest skulde Standen være 15"’
16/4. Forskjellen. 2/4 svarer, da Bredden var 72". til
en Afstand af 0.18 Kvartmil.
Den 24de Juli. da Expeditionen kom tilbage til
Hammerfest fra den anden Tur. regnedes ombord med
Kronometerstanden 15m 31 \ Den efter Signalerne den
28de Juli korrigerede Stand er 15m 32/6. Forskjellen.
1/6. svarer, da Bredden er 73". til en Afstand af 0.12
Kvartmil.
Den 24de August, da sidste Observation toges paa
Tilbagerejsen fra Spidsbergen til Tromsø, regnedes Standen
af Kronometret ombord til 16m 2/0. Efter Verifikationen
den 28de i Tromsø skulde den være 16"’ 3/0. Forskjellen,
1/0. svarer, da Bredden var T41 2°, til en Afstand af 0.06
Kvartmil.
Tager man Hensyn til Usikkerheden af Størrelsen af
Kimmingclalingen — vi regnede med en konstant Værdi
for alle fra Hyttedækket tagne Solhøjder — der beror paa
Horizontalrefraktionen, og til Virkningen af Irradiation til
at gjøre den iagttagne Solradius mere eller mindre for stor.
eftersom Solbilledet ses mere eller mindre lyst, kan vel den
sandsynlige Fejl af en paa Søen maalt Solhøjde neppe
sættes under ± l’. Da i Regelen nedre Solrand maaltes, gjør
Irradiationen de niaalte Højder for smaa. Bredderne for
store ved Middag, for smaa ved Midnat, Timevinklerne
for store paa Vestsiden, for smaa paa Østsiden, østlige
Længder for store paa Vestsiden, for smaa paa Østsiden,
vestlige Længder for smaa paa Vestsiden, for store af
Observationer paa Østsiden.
Saa ofte Anledning gaves, og det paa ganske faa
Undtagelser nær i Regelen hver Dag, og særlig ved
Ankomsten til en Arbejdsstation, korrigeredes Bestikket ved
Observationerne. Disse beregnedes, altid (undtagen
Meridianhøjder) med 2 vilkaarlige Bredder eller, naar de var nær
Meridianen, med 2 vilkaarlige Længder. Nautical
Almanacs Tabeller benyttedes. Stedlinien blev afsat i Kartet
som en ret Linie mellem de 2 saaledes bestemte Punkter.
Ved Hjælp af den imellem 2 Observationer udsejlede Kurs
og Distance bestemtes den paaværende Plads i hver af
Stedlinierne. Stationernes Bredde og Længde bestemtes
saaledes af mig og indførtes i Loddejournalen. Bestik og
Observationer svarede i Regelen meget godt. Under
Skrabning og Trawling blev vi imidlertid altid sat ud af Bestik,
da det var vanskeligt at holde Rede paa Kurser og udløbne
Distancer under disse Manøvrer.
Efter det ovenfor anførte om vore Kronometres Gang
og om den sandsynlige Fejl af en maalt Solhøjde fremgaar
det. at vore Værdier for Stationernes Bredde og Lamgde
har en sandsynlig Fejl af mellem 1 og 2 Minuter.
Folden største Dels Vedkommende overstiger Fejlen ikke
synderlig 1 Minut.
Hammerfest, we assumed the error of the chronometer to
be 15"’ 18/8. From the verification at Hammerfest on the
10th, it was found to have been 15’" 16/4. The difference.
2/4, corresponds on the 72nd parallel of latitude to 0.18
of a nautical mile.
When returning to Hammerfest on the second cruise,
we assumed the error of the chronometer for an
observation taken July 24th to be 15’" 31 \ Corrected’at
Hammerfest on the 28th by comparison with the time-signals, it proved
to have been 15"’ 32/6. The difference. 1/6. corresponds,
in latitude 73°, to 0.12 of a nautical mile.
On the 24th of August, when returning from
Spitzbergen to Tromsø, we assumed the error of the
chronometer to be 16"’ 2/0. Verified at Tromsø on the 28th. it
was found to have been 16"’ 3/0. The difference. 1/0,
corresponds, in latitude 74" 30’. to 0.06 of a nautical mile.
If we consider the difficulty of determining the dip
•of the horizon. — a, constant value was assumed for all
solar altitudes taken from the roof of the roundhouse. —
depending as it does on horizontal refraction, and also
take into account the effect of irradiation in magnifying to
a greater or less extent the diameter of the sun. according
as the solar disk appears more or less luminous to the eye
of the observer, the probable error of a solar altitude taken
at sea can hardly be put at less than i l’. The altitude
of the lower limb having as a rule been observed, the effect
of irradiation would make the measured altitude too low.
the latitude too high at noon, too low at midnight, the
hour-angles too great west, too small east, the results for
longitude east too high on the west side, too low on the
east side, for longitude west too low on the west side, too
high on the east.
Whenever opportunity offered, which, as a rule,
was almost every day. and in particular on arriving at a
sounding-station, we corrected our dead-reckoning by
means of observations. These were always computed
(excepting only meridional altitudes) with two optional latitudes,
or. when taken near the meridian, with two
optional-longitudes. The Tables used were those of the Nautical
Almanac. The line of equal altitudes was marked out on the
chart as a straight line between the two points thus
determined. The ship’s position on each of the lines of equal
altitudes was computed from the course and the distance run
between the observations. I thus determined the latitude
and longitude of the observing-stations. and entered the
results in the sounding-journal. The dead-reckoning and
the observations exhibited in general satisfactory agreement.
Meanwhile, we were invariably out of our reckoning after
working the dredge or trawl: to calculate the day’s work
correctly is next to impossible with such operations in hand.
From what has been stated above concerning the rate
of our chronometers and the probable error of an observed
solar altitude, it is evident that the values for the latitude
and longitude of the observing-stations will have a probable
error of from 1 to 2 minutes. For the greater part of
them, the error will not much exceed a minute.
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