Deviationen.. Værdien af B varierede i 1878 fra 22° 
(Vardø) til 30° (Nordspidsbergen), eller i det Hele 8". I 
1877 varierede B højst 5°. I dette og det foregaaende 
Aar benyttedes de hvert Aar i Husø bestemte Deviations- 
yerdier. Deviationsprøven i Vestfjorden den 10de August 
1877 kunde ikke benyttes til Reduction af dette Aars Ob- 
servationer, da nogle Jernmassers Stilling ombord ved den 
forsætlig vare noget forandrede. Ved denne Prøve, samt 1 
1878, var Deviationen 0 for Nord og Syd, og meget nær 
Maximum for Øst og Vest. 
Den til Vindobservationernes Reduction benyttede 
Misvisning er væsentlig taget efter de under selve Expeditio- 
nen af Capt. Wille, dels paa Land, dels paa Søen tagne 
Declinationsbestemmelser. Paa det ovenfor under No. 1 
nævnte Kart vare Isogoner for hver dte Grad optrukne 
efter de ved Deviationsprøverne fundne Værdier af Misvis- 
ningen. I Land bestemtes Misvisningen 1 Husø, i Reykja- 
vik, i Namsos, i Bodø, i Tromsø og i Hammerfest. De 
benyttede Verdier af Misvisningen stemme paa det aller- 
nærmeste med det af “Deutsche Seewarte” publicerede Iso- 
gonkart?, til hvilket Nordhavs-Expeditionens Resultater ere 
benyttede. 
Skibets Fart bestemtes i 1876 ved den almindelige 
Log eller ved Patentlog, i 1877 og 1878 med *Vandloggen”. 
Om denne indeholder Capt. Willes Afhandling om *Appara- 
terne og deres Brug” følgende Beskrivelse: 
Paa et bekvemt Sted i Maskinrummet bores et Hul 
i Skibsbunden og fores med et I Toms Rør. Over dette 
anbringes med Flens Røret b (se den lille Figur) saaledes, 
at Aabningen i dette danner en Fortsættelse af Hullet 1 
Bunden. Paa Midten af dette Rør er en konisk Kran og 
omkring dets øvre Ende er Skruegjænger til Pakningsringen 
c. Gjennem Roret b og Hullet i Skibsbunden nedsættes 
Røret å saa langt, at den lille Aabning i dets nedre Ende, 
der forøvrigt er lukket, kommer omtrent 0.”5 (20 Tommer) 
under Skibsbunden og visende ret forefter. Denne Afstand 
fandt vi var den hensigtsmæssigste. En mindre Afstand 
bragte Hullet for nær det af Skibsbunden medslæbte Vand, 
en større Afstand rønnede for meget paa det fritstaaende 
Rør under større Fart. Pakningsskruen c tilskrues. Oven- 
for c bør Røret å have en mindre Kran d. Fra a’s øvre 
Ende gaar et tyndt Blyrør til Stigerøret g, der har omtrent 
10 (4 Tommers) Diameter. Dette maa placeres midt- 
skibs, verticalt og saa lavt. at dets nedre Ende er godt 
under laveste (nederste) Vandlinies Plan. Det er forsynet 
med Blænde, for at ikke Vandet under Skibets Bevægelse 
skal pumpe i Røret. I dette Stigerør er anbragt en Flyder, 
' Forøvrigt henvises til Capt. Willes Afhandlinger: Om *Appa- 
raterne og deres Brug”, hvor Skibets Navigering er beskrevet, og om 
“De maonetiske Observationer” i denne Generalberetning. 
? Annalen der Hydrographie und maritimen Meteorologie 1880. 
Heft VII. 
NI 
value of the deviation* could be found on Plate 2. The 
value of B ranged in 1878 from 229 (Vardø) to 30° (North 
Spitzbergen), or 8°. In 1877 the range was scarcely 
5°, In this and the previous year we calculated with 
the deviation-values found on each cruise at Husø. The 
deviation determined in the Vestfjord on the 10th of Au- 
cust 1877 was of no assistance for reducing that year’s 
observations, various masses of iron on board having been 
purposely changed in position. On this occasion, as also 
in 1878, the deviation was 0 for north, and the maximum 
very nearly for due east and west. 
The Variation for reducing the wind-observations was 
principally taken from Captain Wille’s determinations of 
declination, performed during the Expedition, partly on 
shore, partly at sea. On Chart 1, mentioned above, the 
jsogonic lines for every five degrees were drawn in accor- 
dance with the values for variation found from the obser- 
vations for determining the deviation. On shore, the decli- 
nation was determined at Husg, at Reykjavik, at Namsos, 
at Bodø, at Tromsø, and at Hammerfest. The values for 
variation agree very closely with those in the Isogonic Chart 
published by “Deutsche Seewarte,* for which the results 
of the Norwegian North-Atlantic Expedition have been 
adopted. 
The Rate of the Ship was determined in 1876 by the 
ordinary log or by the patent log; in 1877 and 1878, by 
the *water-log.” Of this instrument Captain Wille has 
given the following description in his Memoir on “The 
Apparatus, and How used”: — 
“In some convenient spot in the engine-room, a hole 
was bored in the ship’s bottom to receive a one-inch metal 
tube, having fixed on to its top end the flange of the tube 
b (see small Figure), in such manner that the bore of the 
latter would form a continuation of the hole in the ship's 
bottom. This tube had a conical stop-cock, and its upper 
extremity screw-threads fitting into the gland c. The tube 
a was passed through the tube b and the hole in the ship's 
bottom, till the small aperture at its lower end, which for 
the rest was closed up, had been made to project about 
20 inches beneath the bottom of the vessel, while pointing 
straight forward. This we found, by repeated experiment, 
to be the right distance. If diminished, it would bring the 
aperture too near the water carried along by adhesion to 
the ship's bottom; and if increased, it would, with greater 
speed, expose the projecting tube to a serious strain. The 
gland c has now to be screwed on. A little above the 
gland. the tube @ should have a smaller stop-cock d. From 
the top of a a slender leaden pipe led to the upper tube 
g, which had a diameter of nearly 4 inches. This tube 
must be given a vertical position amidships, and far enough 
1 For the rest, the reader is referred to Captain Wille’s Memoir 
on “The Apparatus, and How used,” in which the navigation of the 
ship will be found described, and to his “Magnetic Observations,’ 
both published in the General Report. 
* Annalen der Hydrographie und maritimen Meteorologie, 1880. 
Heft VII 
