19 Anveridelse i S0en. Betingelser for dens heldige Anven- delse er et bredt Fartpj. en let Styring, roligt Yejr og tilstrtekkelig Tid, saint fremfor alt en s'aadan Plads for In- strumentet, at de med samme tagnie Bestemmelser af In- klination og Intensitet karmonerer. . Det er saaledes kun Misvisnings-Observationerne, der have ledet til brugbare Resultater. Fprend jeg gaar over til ah beskrive den i Soen an- vendte Fremgangsmaade og give de beregnede Resultater, • | maa jeg forst omtale Resultaterne af de Observationer, som gjordes i Hus0 til Bestemmelse af Kompassets Deviation. Den 13de Juni 1876. svang jeg Skibet paa Huso Havn for at bestemme Kompassets Deviation. Svingningen udfortes ved Trosser, fastgjorte i Land. For liver anlagt Kurs (16 forskjellige Streger), paa hvilke der observeredes, pejledes med Kompasset Varden paa Poldetind. Samtidig observerede paa Teltpladsen i Land Prof. Molin, paa givet Signal, Magnetometret til Bestemmelse af den absolute Deklination. Fra Teltpladsen var, som ovenfor Side 8 an- fprt, Azimut af Varden paa Poldetind N 48° 7/5 E. Da Fartojet (Standard Kompasset ombord) under Svingningen laa meget nser i. Vertikalplanet’. mellem Teltpladsen og Poldetind, bliver Azimut af Poldetind for Standard-Kom- passet ombord N 48/T E. Poldetinds Afstand fra Huso er 10 Kvartmil, saa at en Forrykning lodret paa Sigte- lineu mellem begge Steder af 0.°1 svarer til 32.4 Meter, en Afstand, der er meget storre end Forrykningen af Kom- passets Plads under Svingningen. « Trsekkes ■ Azimut af Poldetind — 48.°1 — fra Pej- lingen af Poldetind, faar man det sande Azimut af Kom- pasnaalens Nordende eller den devierende Misvisning. Den fplgende Tabel indeliolder Observationerne og de deraf be- regnede Vserdier for devierende Misvisning. superable obstacles to the use of the Fox circle at sea. Tbe conditions for successful observation with the instru- ment 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 trust- worthy 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 Huso for deter- mining the deviation of the compass. On the 13th of June, 1876, I swung the ship in Huso harbour, by means of hawsers, to obtain the devia- tion of the compass. For every course by compass (1.6 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 mag- netometer 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 Huso 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 observa- tions, and the values computed from them, for deviating variation. Klokkeslet. (Hour.) Anlagt Kurs paa St. Kompas. (Ship's Head by Stud. Compass.) Pejling af Poldetind. (Hearing 6/ Poldetind.) Devierende Misvisning. (Deviating Variation.) IO h 34™ a. m. S o.°2 E N 66.°o E N 17.°g W .’ 10 55 S 21. b E 75- 1 27. 0 I I 58 S 45. 0 E 82.3 34- 2 o 28 p. m. S 67. 4 E • 85- 4 37- 3 O 49 E 85. 0 36. 9 I 5 N 67. 5 E 82. 7 34- 6 I 29 N 44. 9' E 77- 7 29. 6 I 32 N 22. 5 E 72- 5 . 2 4- 4 .1 5i N 0. 2 E 67. 0 18. 9 4 15 N 22. 7 W 61. 5 *3-4. 4 32 ' N 45- 3 W 56- 3 8. 2 4 52 N 67. 5 W 51- 9 ' 3-8 5 2 I N 89. 7 W 48. 6 o- 5 5 40 S 67. 2 w 48. 3 O. 2 5 58 s 45-3 W 50. 5 ■2. 4 6 15 S.22.8 W 57- 1 9,0 6 45 S 0. 7 E 66. o’ •17.9

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