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.
•19
Anvendelse i Soen. Betingelser for dens heldige
Anvendelse er et bredt Fartøj, en let Styring, roligt Vejr og
tilstrækkelig Tid. samt fremfor alt en saadan Plads for
Instrumentet, at de med samme tagne Bestemmelser af
Inklination og Intensitet harmonerer.
Det er saaledes kun Misvisnings-Observationerne, der
have ledet til brugbare Resultater.
Førend jeg gaar over til at beskrive den i Søen
anvendte Fremgangsmaade og give de beregnede Resultater,
maa jeg først omtale Resultaterne af de Observationer, som
gjordes i Husø til Bestemmelse af Kompassets Deviation.
Den 13de Juni 1876 svang jeg Skibet paa Husø
Havn for at bestemme Kompassets Deviation. Svingningen
udførtes ved Trosser, fastgjorte i Land. For hver anlagt
Kurs (16 forskjellige Streger), paa hvilke der observeredes,
pejledes med Kompasset Varden paa Poldetind. Samtidig
observerede paa Teltpladsen i Land Prof. Mohn. paa givet
Signal. Magnetometret til Bestemmelse af den absolute
Deklination. Fra Teltpladsen var, som ovenfor Side 8
anført, Azimut af Varden paa Poldetind X 48° 7/5 E. Da
Fartøjet (Standard Kompasset ombord) under Svingningen
laa meget nær i Vertikalplanet mellem Teltpladsen og
Poldetind. bliver Azimut af Poldetind for
Standard-Kom-* passet ombord N 48.°1 E. Poldetinds Afstand fra Husø
er 10 Kvartmil. saa at en Forrykning lodret paa
Sigtelinen mellem begge Steder af 0.°1 svarer til 32.4 Meter,
en Afstand, der er meget større end Forrykningen af
Kompassets Plads under Svingningen.
Trækkes Azimut af Poldetind — 48.° 1 — fra
Pejlingen af Poldetind, faar man det sande Azimut af
Koin-pasnaalens Nordende eller den devierende Misvisning. Den
følgende Tabel indeholder Observationerne og de deraf
beregnede Værdier for devierende Misvisning.
superable obstacles to the use of the Fox circle at sea.
The conditions for successful observation with the
instrument are a vessel broad in the beam and easy to steer,
calm weather and sufficient time, and above all such a
position for the instrument as will admit of satisfactory
agreement in its determinations of inclination and intensity.
Hence, the only observations attended with
trustworthy results. were those taken to find the declination.
Before proceeding to describe the method adopted at
sea and give the computed results, I must first set forth
the results of the observations taken at Husø for
determining the deviation of the compass.
On the 13th of June, 1876, I swung the ship in
Husø harbour, by means of hawsers, to obtain the
deviation of the compass. For every course by compass (16
different points) on which I observed, the bearing of the
Poldetind signal was taken with the compass, Professor
Mohn. at a given signal, simultaneously observing the
magnetometer in the tent on shore, to determine the absolute
declination. As previously stated, page 8, the azimuth of
the Poldetind signal from the tent was N. 48° 7.’5 E.
Now. as the ship (standard compass on board) lay when
swinging very nearly in the vertical plane between the tent
and Poldetind, the azimuth of Poldetind for the standard
compass on board will be N. 48.° 1 E. The distance of
Poldetind from Husø is 10 miles; and hence a change in
position of 0.°1 perpendicular to the line of vision between
both places, corresponds to 32.4 metres, a distance much
greater than is that corresponding to the change in the
position of the compass during the swinging of the ship.
If the azimuth of Poldetind — 48.° 1 — be subtracted
from the bearing of Poldetind, we get the true azimuth of
the north end of the compass-needle, or the deviating
variation. In the following Table are given the
observations. and the values computed from them, for deviating
variation.
Klokkeslet.
{Hour.)
Anlagt Kurs
paa St. Kompas.
(Ship’s Head
by St ml. Compass.)
Pejling
af Poldetind.
0Bearing
of Poldetind.)
Devierende
Misvisning.
(Deviating
Variation.)
ioh 34" a- m- S 0.°2 E X 66.°o E X 17-°g
IO 55 S 21. 6 E 75- i 27.0
11 5» S 45. 0 E 82. 3 34. 2
9 28 p. 111. S 67.4 E «5-4 37- 3
0 49 E 85.0 36- 9
i 5 X 67. 5 E 82.7 34-6
i 29 X 44. g E 77- 7 2g. 6
i 32 X 22. 5 E 72- 5 24- 4
i 51 X 0.2 E 67. 0 18. g
4 15 X 22. 7 W 61.5 13- 4
4 32 N 45- 3 W 56.3 8. 2
4 52 X 67. 5 W 51- 9 3-8
5 2 i X 8g. 7 w • 48. 6 5
5 40 S 67. 2 w 48. 3 0. 2
5 58 . S 45-3 AV 5°- 5 ■. 2- 4
6 15 S 22. 8 W 57- 1 g. 0
6 45 S 0. 7 E 66. 0 17. 9
<< prev. page << föreg. sida << >> nästa sida >> next page >>
