Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
99
Fejlene under Sejlads vestover bliver næsten den samme
som Summen af Fejlene under Sejlads østerover — indenfor
den enkelte Gruppe.
Maximumsfejlen i Klokkeslettet rammer Observationen
Kl. 12 Middag. Efter Observationstabellerne (S. 49—96)
udtog jeg, for hver benyttet hel Observationsdag,
Længdeforandringen fra Middag til Middag (regnet positiv, naar vi
rejste mod Øst, negativ mod Vest) og omgjorde denne til
Tidsminutter. For hver af de hele Grupper toges Summer
af de positive og Summer af de negative Værdier. Deres
Forskjel, divideret med Antallet af Dage i Gruppen, giver
den gjennemsnitlige Fejl i Klokkeslettet, som
Middagsob-servationen har været udsat for. Denne overstiger, som
man nedenfor vil se, i intet Tilfælde 5 Minutter, altsaa en
temmelig fuldkommen Compensation. Desuden udregnede
jeg den højeste positive og negative Værdi, som overhovedet
forekom inden Gruppen. Disse dreje sig om 30 Minutter,
og overstige ikke 36 Minutter. I 1878, da Expeditionen
sejlede paa meget høje Bredder mellem Spidsbergen og
Grønland, stilledes undertiden Skibsuret efter Stedets sande
Tid ogsaa ved Midnat, hvorved Fejlen i Klokkeslettet er
yderligere formindsket. Hertil er dog ikke taget Hensyn
ved Beregningen af Fejlens Maximumsstørrelse.
Efter de corrigerede Middeltal for hvert af de 24
Observationsklokkeslet i de valgte Grupper beregnedes
Formelen for den daglige Periode efter den Besselske Methode.
Antallet af Led, der ere beregnede, er noget forskjelligt
efter de forskjellige Tilfælder. Da der paa Grund af
Observationernes Faatallighed alene kunde blive Spørgsmaal
om at erholde en første Tilnærmelse til Kundskaben om
de daglige Perioder, ere i Regelen, foruden Mediet, kun 2
Led blevne beregnede. Perioderne for Lufttrykket, nogle
Perioder for Luftens Temperatur, en enkelt (1876) for
Vanddampenes Tryk. den relative Fugtighed og Vindens
Hastighed ere beregnede med 4 periodiske Led.
Efter Dr. H. Wilds Forslag1 har jeg forsøgt, efter
de paa Rudepapir afsatte observerede Værdier at trække
paa Frihaand den sandsynligste Curve for de forskjellige
Perioder. I de allerfleste Tilfælder faldt denne Curve
meget nær sammen med den beregnede. Hvor der viste
sig mere merkelige Afvigelser, stillede det sig for mig meget
tvivlsomt, hvilken af begge jeg skulde foretrække. For at
give Læseren fuld Anledning til at dømme og vælge, opfører
jeg i Tabellerne og i Figurerne Pl. I til IH saavel de
observerede som de efter de Besselske Formler beregnede
Curver, og skal for hvert Tilfælde gjøre Rede for disses
større eller mindre Overensstemmelse med deraf flydende
Afvigelser i Bestemmelsen af Epocherne og Værdierne for
Maxima og Minima samt Epocherne for Middelværdiens
Indtræffen.
1 Die Temperaturverhältnisse des Russischen Reiches. op. cit
S. :s.
errors on the passage west being very nearly the same as
the sum of the errors on ’the passage east — within any
individual group.
The maximum error in the hour vitiates the
observation taken at noon. From the Observation Tables (pp. 49—
96), I took, for every whole "observation day," the
variation in longitude from noon to noon (calculated as positive
when steaming east and negative when steaming west), and
converted it into minutes of time. For each of the whole
groups was then taken the sum of the positive and the sum
of the negative values. Their difference, divided by the
number of days in the group, gives the average error in
the hour to which the observation taken at noon has been
exposed. This error, as shown below, will in no case exceed
5 minutes. — therefore a tolerably perfect compensation.
Furthermore, I computed the highest positive and negative
values that occurred within the group. These values average
about 30 minutes, and do not exceed 36 minutes. In 1878,
when the Expedition was cruising in very high latitudes,
between Spitzbergen and Greenland, the ship’s clock was
sometimes also set to apparent time at midnight, thus still
further reducing the error in the hour. In such cases,
however, regard was not had to this circumstance when
computing the maximum value of the error.
From the corrected mean values for each of the
twenty-four hours of observation in the groups selected, the formula
for the diurnal period was computed according to Bessel’s
method. The number of terms computed is somewhat
different in the sevei’al cases. Since, owing to the limited
number of observations, it was out of the question to attempt
more than a first approximation as regards our knowledge
of the diurnal periods, as a rule 2 terms only, exclusive
of the mean, have been computed. The periods for the
pressure of the air, a few periods for the temperature of
the air, one period (1876) for the force of vapour, the
relative humidity and the velocity of the wind, are computed
with 4 periodical terms.
Acting on the suggestion of Dr. H. Wild,1 I have
tried, from the observed values laid down on ruled paper,
to draw the most probable freehand curve for the different
periods. In the great majority of cases this curve was
found to coincide very neai’ly with that computed. Wherever
any considerable deviations occurred, I was extremely
doubtful which of the two to give the preference. With a view
to afford the reader ample means of judging and selecting,
I have set forth in the Tables and in Pl. I to HI both
the observed curves and those computed from Bessel’s
formulae, and shall in each case account for the greater
or less agreement, and the variations resulting therefrom, in
the determination of the epochs and the values for maxima
and minima, as also of the epochs for the occurrence of the
mean values.
’ Die Temperaturverhältnisse ties russischen Reiches, op. cit.
p. 8.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
