Den sandsynlige Fejl i Bestemmelsen af Skibets Ha- 
stighed sætter jeg, efter de ovenfor givne Bemerkninger 
herom, for 1876 dv = + 0.”5 pr. Secund. For 1877 
og 1878 derimod, da Vandloggen kunde observeres med 
en Nojagtighed af + 0.2 Knob, eller 0.”1 pr. Secund, 
setter jeg dv = + 0.”2 pr. Secund, idet der bør tages 
Hensyn til, at Strom giver Fartøjet en anden Fart gjennem 
Luften, end det har gjennem Vandet, og at de smaa Hastig- 
heder ikke kunne maales med den Nøjagtighed som de større. 
Hertil kommer ogsaa Usikkerheden ved Vandloggens Nul- 
punkt, der altid vil være tilstede, ihvorvel dette Punkt 
stadig blev verificeret under de hyppige Standsninger, der 
gjordes ved Lodning og Skrabning. 
Den sandsynlige Fejl (dy) af en over Compasset 
observeret Vindretning sætter jeg, som ovenfor allerede 
nævnt, til + 5° eller /, Streg. Den kan antages at være 
den samme i alle 3 Expeditions-Aar. 
Disse 3 Fejl ere i Regelen samtidigt indvirkende paa 
den beregnede Vindhastighed og den beregnede Vindretning, 
Sættes i Ligningerne (11) og (12), efter hvilke denne Ind- 
flydelse kan beregnes, 
The probable error in the determination of the speed 
of the ship, I put, in accordance with the statement detailed 
above, for 1876, at dv = + 0.”5 per second. For 1877 
and 1878, on the other hand, since the water-log could be 
observed with an accuracy of + 0.2 knots, or 0.”1 per 
second, I put dv = + 0.”2 per second, due regard being 
had to the fact, that a current gives the vessel a different 
rate through the air than she has through the water, and 
also that low velocities cannot be measured with the same 
accuracy as high. Moreover, the uncertainty attaching to the 
zero point of the water-log, which will always exist, though 
the said point was constantly verified during the frequent 
stoppages necessary for sounding and dredging, has to be 
taken into account. 
The probable error (dy) in the direction of the wind 
as observed by the compass, I put, as stated above, at + 
5°, or half a pomt. It may be assumed to have been the 
same on each of the three cruises of the Expedition. 
The effect of these 3 errors will as a rule enter 
simultaneously into the computed velocity and the computed 
direction of the wind. Now, substituting in the equations 
(11) and (12), by which this influence can be computed, 
O sm 9 S W små (14) 
w cos y = W cos u + v (15) 
saa faar man følgende Formler, der tildels kunne vere | we get the following formule, which in some cases may 
lettere at regne med. be easier to compute with. 
W 
OW = 8 EY fa — cos u dv tvsinudy (16) 
v sin u sin % E 
du= — Sai w+ - ye y + [1 + pp cose | dy (17) 
Regner man, saaledes som i det Følgende er gjort, 
med en constant W og v, saa beregnes w og y af (14) 
If, as I have done in the following computations, . we 
take a constant value for W and v, w and y are found 
og (15). from (14) and (15). 
Sættes Putting 
‘cos (u — y) = cose = Ur OSE Eva 
COS w b 
w sin (u— Y) 780 = 75 gq = PIN gg = 8 
sin(w— y) 180, smel80  vsmul80 __, 
No mase 
sin u 180 = 
W a os 
w Å 
yr 608 (v — y) = 7, COS € = 1 ++ + c0s u = å 
saa har man i de enkelte Tilfælder den pe Fejl 
af W og wu: 
Den norske Nordhavsexpedition. H. Mohn: Meteorologi. 
| 
the probable error of W and w in the several cases will be 
