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127
Til at beregne Afstanden fra A af de Punkter i
Normalerne, hvor Højden over Niveaufladen er 0.1. 0.2, 0.3
Meter o. s. v. have vi, naar Højden ved Kysten er H,
Afstanden fra A langs Normalen til Kysten X, Højden h i
Afstanden x:
X
x = w- Yh
Efter denne Formel ere Overskjæringspünkterne
mellem Normalerne og Ligehøjde-Linierne beregnede.
Mellem de ovenfor beskrevne Normaler ligger den,
der fører til Midten af Nordsøen. Langs denne har jeg
tænkt mig tre Stykker af Parabelbuer. I et Punkt midt
i Nordsøen, der hvor Ligehøjdelinien for 0.7 Meter har sit
sydligste Punkt, er Toppunktet for en Parabel med opad
vendende Axe, hvis Ordinat ved Texel er 0.8 Meter. Her
bliver saaledes Hastigheden Nul i Punktet midt i Nordsøen.
Ved Texel bliver efter Formelen
h „ „ H
u — — eller U = -j-^
kx kA
med h = 0.8 —0.7 = 0.1 m, r/> = 54°.ö og x = 310 km
Hastigheden u — 0.05 m. p. S.
Fra Midtpunktet i Nordsøen til A deler jeg
Afstanden i to Dele; hver af dem bliver 700 km. Igjennem den
sydlige Del tænker jeg mig en Parabel med Axen nedad
og Toppunktet i Nordsø-Midtpunktet. Gjennem den
nordlige Del lægger jeg en med denne congruent Parabel med
Toppunktet i A og Axen opad. Højdeforskjellen mellem
Yderpunkterne er 0.7 m, følgelig i begge Parabler H — 0.35 m.
og X— 700 km. Der, hvor de støde sammen, 700 km fra
A, bliver Højden 0.35 m og Hastigheden U = 0.076 m.
p. S. Efter disse Data beregnedes Ligehøjdeliniernes
Skjæringspunkter med Normalen og afsattes i Kartet.
Fra Punktet B føres en Normal til Norges Kyst ved
Vesteraalen. Vi have A’ = 535 km, <p = 69°.-6, if =0.8 in,
og finde U = 0.215 m. p. S.
Fra B er ført en Normal langs Havfladens
Fordybning i Østhavet til Jugor-Strædet (Novaja Senilja). Langs
denne er tænkt en Parabelbue, med Toppunkt i B og Axen
opad. I Østhavet følger nemlig Strømmen de herskende
Vinde. I Nordsøen var dette ikke Tilfældet. Vi have
X = 2100 kiil, (p = 72°.9, H= 0.8 m, og finde ved
Jugor-strædet U = 0.054 ni. p. S. Efter disse Data ere
Lige-højdeliniernes Skjæringspunkter med Normalen beregnede.
Fra denne samme Normal, der danner Østhavets
Strøm-Axe, lagdes Parabelbuer tvers paa Strømlinierne til Norges
og den murmanske Kyst. Afstanden a maaltes paa Kartet.
To compute the distance from A of the points in the
normal lines at which the height above the surface of level
is 0.1. 0.2, 0.3 metre, etc., we have, when the height at
the coast is H, the distance from A along the normal line
to the coast X, and the height h at the distance x: —
X
x = VH - VI,
According to this formula, the points of intersection
between the normal lines and the lines of equal height
have been computed.
Between the fore-described normal lines lies that
extending to the middle’of the North Sea. Along this line
I have laid three arcs of parabolic curves. At a point in
the middle of the North Sea where the line of equal height
for 0.7 metre reaches its most southern point, I put the
vertex of a parabola with upward-pointing axis, the ordinate
of which at the Texel is 0.8 metre. Here, therefore, the
velocity will - be zero at the point in the middle of the
North Sea. At the Texel, according to the formula
h rT H
u — -7—, or U =
kx kA
with h = 0.8 —0.7=0.1 m, r/> = 54°.5, and a: = 310 km.,
the velocity u — 0.05 m. per see.
From the point in the middle of the North Sea to
A, I divide the distance into two parts, each measuring
700 kilometres. Throughout the southern part I assume
a parabola to pass, with its axis pointing downwards and
its vertex in the mid-point of the North Sea.
Throughout the northern part I lay down a parabola congruent with
the former, having its vertex in A and its axis pointing
upwards. The difference in height between the outermost
points is 0.7 metre; hence in both parabolas H— 0.35 metre
and X — 700 kilometres. Where they meet, viz., 700
kilometres from A, the height will be 0.35 metre and the
velocity U — 0.076 metre per second. According to these
data, the points of section for the lines of equal height
with the normal line have been computed and set down on
the map.
From the point B a normal line has been drawn to
the coast of Norway, at Vesteraalen. Here we have X= 535
kilometres, </ = 69°.6, H — 0.8 metre, and get U= 0.215
metre per second.
From B a normal line is made to pass along the
surface-depression in the Barents Sea as far as Jugor Strait,
Novaja Senilja. Along this depression is assumed a
parabolic curve, with its vertex in B and its axis pointing
upwards. In the Barents Sea, the current takes the direction
of the prevailing winds. In the North Sea, this was not
found to be the case. We have X — 2100 kilometres,
(f = 72°.9, H— 0.8 metre, and get at Jugor Strait U= 0.054
metre per second. According to these data, the points of
section for the lines of equal height with the normal line
have been computed.
From the same normal line, which constitutes the
current-axis of the Barents Sea, parabolic curves were laid
straight across the stream-lines to the Norwegian and the
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