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5
Naar nu Instrumentet registrerer n Dele i 3U Secunder, eller
i 1 Secund, bliver den foreløbig beregnede
Vindhastighed »’ = 3y29 = 0.96667 n.
Vi faa saaledes
Sand Vindhastighed v = 1.518 -4- 0.81600 n.
Foreløbig Vindhastighed i/ = 0.96667 n.
Correction v — v’ =z 1.518 — 0.15167 «.
V
Sættes her n = r, .„„ faaes
U.96667
0.815
" - " 0.96667 "
v = 1.518 + 0.8431 V’
, ,.,„ 0.15167 ,
og „ _ r = 1.018 - mm v
v — v’= 1.518 — 0.1569 v’
Herefter beregnes følgende Correctionstabel.
30 X 2 7c r, or 29.m0. If the instrument registers n
divisions in 30 seconds, or ^ division in one second, the
computed approximate velocity of the wind v’ will = ^ 29 =:
0.96667 n.
Hence, we have —
True Velocity of Wind v = 1.518 + 0.81500 n.
Approximate Velocity of Wind y’ = 0.96667 n.
Correction v — v’ — 1.518 — 0.15167 n.
Now, putting « = we get
" = L518 + Ö96667
v = 1.518 + 0.8431 v’
, , 0.15167 ,
and v v — I.0I8 - ^^ v
v — v’= 1.518 — 0.1569 v’
From this formula the following Table of Corrections
has been computed.
v’ V Corr.
\ fra (from) 0 * fra (J’rom) o
0 til (to) + I.J ’ til (to) + I.J
I + 1-4
2 3-2 4 1.2
3 4.0 +1.0
4 4-9 + 0.9
5 5-7 + 0.7
6 6.6 + 0.6
7 7-4 + 0.4
8 8-3 + 0.3
9 9.1 + 0.1
10 9.9 -O.I
11 10.8 — 0.2
12 11.6 — 0.4
= 9.m7.
Man ser, at Fejlen ikke overstiger lm pr. Secund
mellem v’ 3m og v’ = 16m. at den er 0, naar v’
1.518
Ö.1569
Da det anvendte Instrument og de anvendte
Obser-vationsmethoder. i Forbindelse med Vindhastighedens egen
variable Størrelse selv i kortere Tidsrum end 30 Secunder,
neppe tør antages at kunne maale Vindhastigheden nøjere
• end med omkring 1 Meters Nøjagtighed pr. See., da
fremdeles den midlere Vindhastighed, der er maalt i 1876, er
mellem 9m og !0m, og de maalte Hastigheder sjelden ere
mindre end 3m og større end 16’", og da desuden hertil
kommer, at den Nøjagtighed, hvormed Skibets Fart i
Ob-servationsøjeblikket kunde bestemmes i 1876, oftere neppe
var større end at Fejlen kunde dreje sig om 1 til 2 Kvart-
when v’ :
: 9.m7.
The error is thus seen not to exceed 1 metre per
second between v’ =. 3m and v’ — 16"1, and to be nil
1.518
0.1569
As both the instrument and the modes of observation
adopted, in conjunction with the varying velocity of the
wind even in a shorter interval than 30 seconds, will hardly
admit of determining the velocity of the wind with greater
exactness than 1 metre per second; moreover, as the mean
velocity of the wind determined in 1876 was between 9m
and 10m, and the measured velocities were seldom less than
3m and greater than 16m; and besides, as the accuracy with
which the speed of the vessel at the moment of observation
was determined in 1876, was often not greater than that
the error ranged from 1 to 2 miles an hour, or 0.m5 to
v’ v Corr.
13 12.5 —0.5
14 13-3 —0.7
15 14.2 —0.8
16 15.0 —1.0
17 15.8 —1.2
18 16.7 — 1.3
19 17-5 — 1.5
20 18.4 — 1.6
21 19.2 — 1.8
22 20.1 — 1.9
23 20.9 —2.1
24 21.7 —2.3
25 22.6 — 2.4
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