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48
Sættes Coefficienten 31 lig 1. Kvartmilen lig 7co af en
Ækva-torsgrad og g lig 9.m810 (50° N. Br.), saa faar man den
følgende Tabel for Skalaens Inddeling.
ficient M to equal 1. a mile to equal 1/B0 of an equatorial
degree, and g to equal 9.810m (in lat. 50° N.), we
have-the following series of figures for graduating the scale.
Fart. (fipc.’J.) Skala. (Scale. 1
Kvartmil i Timen. (Jfiles an Hovr.) Meter. Norske Fod. !Xorw Feet) Eng. Fod. (Eng. Feet.)
I 0.014 O.o43 O.o44
2 0054 O.I72 O.i78
2-5 0.085 O.27o O.278
3 0.122 O.388 O.4oo
3-5 O.166 O529 05 44
4 O217 O.69o 0.7 11
4-5 O.274 O.874 0.899
5 0338 I.O79 1.110
5-5 O.4io I3O5 1-343
6 O.487 i 553 ■ 599
6.5 0572 1823 1.876
Yil man efterse, om Røret gjennem Bunden er i
Orden, stænges Kranen d, Pakningsstykket / afskrues, og
Blyrøret bøje’s noget til Side: man løsner paa Pakningsringen
c, Røret a løftes op, indtil dets nedre Ende har passeret
Kranen paa Roret b. hvorefter denne afstænges, og Røret
a kan løftes helt op og ettersees.
Ved Brugen af Vandloggen maa to Ting haves i
Erindring:
1) at Skalaens Nulpunkt eller rettere Snorens Længde fra
Flyderen til Vægten, der tjener til Viser paa Skalaen,
retter sig efter Skibets Dybgaaende. ’og
2) Fejlen, der foraarsages ved stadig Krængning.
Med Hensyn til det første Punkt, reguleres dette
lettest derved, at man standser Skibets Fart. udtager
Trækilen og flytter Loddet paa Nul. Det hele kan udføres i
nogle Minutter. Ved de hyppige Stopninger, som Lodning
og Skrabning foranledigede, kunde vi paa
Nordhavs-Expe-ditionen altid holde Vandloggen skarpt justeret. Paa
Sejlskibe vil Forbruget ombord ikke saaledes forandre
Dyb-gaaendet. som paa Dampskibe, men man bor dog imellem
foretage et Par nøjagtige Logninger med den almindelige
Log og Uhr, for at kontrollere Vandloggen og eventuelt
justere den paany.
1 Ved Bredde med y = i).’»s:$u bliver Skalastregén for 12
Miles Fart 1.945 Meter, altsaa kun 4""" forskjellig fra
Tabellens. For de mindre Hastigheder bliver Forskjellen
forholdsvis mindre.
To ascertain whether the tube passing through the
ship’s bottom be in order, the stopcock d is turned back,
the gland f screwed oft", and the leaden tube bent a little
aside; then, after partially unscrewing the gland c, the
tube a is lifted up till its lower extremity is just clear of
the cock of the tube b, and when this too has been
turned back, the tube a may be taken out and examined.
When using the water-log. two things must be borne
in pind, viz. —
1) That the position of zero on the graduated scale, or
rather the length of the line from the float to the
weight which plays against the scale, is regulated by
the draught of the ship ; and
2) The heeling error.
As regards the first source of error, the index is best
regulated by stopping the vessel, and then, after taking out
the wooden wedge, placing the weight at zero. This may
be done in a few minutes. With the frequent stoppages
involved in sounding and dredging on the North-Atlantic
Expedition, we could always manage to keep the water-log
accurately adjusted. In sailing-vessels the draught is not
of course as in steamers affected by the consumption of
coal: but now and then the speed should nevertheless be
closely determined with the common log as a means of
testing the results of the water-log. and. if necessary, of
adjusting that instrument anew.
1 In lat. 80° N.. where g = U.8B0’", the division on the scale
denoting a speed of 12 knots will correspond to l.t>4">m,
and thus exhibit a difference of only 4""" as compared with
the figures in the Table. For less velocities, the difference
. will be proportionally reduced.
7 0,663 2.114 2.176
7-5 0.761 2.427 2.498
8 0866 2.761 2.842
8.5 0.978 3.117 3.209
9 i 096 3.495 3.597
9-5 1-222 3.894 4.008
10 1.354 4.314 4.441
10.5 1.492 4.756 4.896
n 1638 5220 5.373
11.5 1.790 5.706 5.873
121 1.949 6.213 6.395
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