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Dækket brudt ved et foran eller agtenfor Skorstenen
ophængt Røgsejl, der enten fordelte Røgen eller nødte den
til at stige saa højt tilvejrs, før den gik agterover, at den
ikke rørte Thermometerhuset.
Med Yinden paa Bougen, tvers eller paa Laaringen
kom Luftstrømmen altid frit fra Havet til
Thermometerhuset. Med Yinden næsten eller ganske ret agterind kunde
det tænkes, at det opvarmede Fartøj og navnlig Skorstenen
kunde give den Luftstrøm, som naaede Thermometerhuset,
en for høj Temperatur. Samtidige Iagttagelser af
Thermo-metre, opstillede ganske paa lignende Maade agterud ved
Roret (Fig. 2, z), viste imidlertid, at Thermometret forud
under Fokkestaget viste samme Temperatur som de agterud,
naar Vinden var agterind. Dette Resultat skyldtes
væsentlig den Højde, i hvilken Thermometrene forud hang, thi
med Vinden forind viste Thermometrene agterud, der stode
i Mandshøjde over Dækket, i Regelen højere end de forud.
De til Lufttemperaturens og Fugtighedens
Bestemmelse benyttede Thermometre vare af Aderman i
Stockholm. De vare hvert Aar sammenlignede i Christiania ved
det meteorologiske Institut med Normal-Thermometer,
deier os sendt fra Kew-Comiteen. De vare inddelte i lj5
Grad og de fundne Correctioner mindre end 0.°1. Til
Thermometerhuset under Fokkestaget udvalgtes 2
Thermometre, hvis Correctioner vare under 0.°05.
I 1876 og tildels i 1877 gjorde jeg nogle
sammenlignende Forsøg med Slyngethermometer og vort tørre
Thermometer forud. Slyngethermometret svingedes oppe paa
Forkant af Hytten, i samme Højde som Thermometret i
sit Hus under Fokkestaget. Resultatet af disse Forsøg
var følgende:
of such smoke was as a rule in a great measure counteracted
by a smoke-sail hoisted either before or behind the
galley-funnel, this sail either dissipating the smoke, or compelling
it to ascend so far up before passing aft that it did not
come in contact with the thermometer-case.
With the wind on the bow, on the beam, or on the
quarter, the current of air reached the thermometer-case
unopposed from the sea. With the wind almost or right
aft, it might be supposed that the heated vessel, and more
especially the funnel, could impart to the current of air on
its reaching the thermometer-case too high a temperature.
Simultaneous observations of thermometers mounted aft in
proximity to the rudder (Fig. 2, z) precisely as described
above, showed, however, that the thermometers under the
fore stay indicated the same temperature as those mounted
aft, when the wind came right over the taffrail. This result
must be ascribed chiefly to the height at which the
thermometers in the fore part of the vessel were suspended;
for, with the wind right ahead, the thermometers at the
stern of the vessel, 5 or 6 feet above the deck, indicated
as a rule a higher temperature than those under the fore
stay.
The thermometers used for determining the
temperature and humidity of the air were by Aderman of
Stockholm. They were each year compared in Christiania with
the standard thermometer of the Meteorological Institute,
presented by the Kew Committee. These instruments were
graduated in fifths of a degree C., and the corrections did
not amount to 0.°1. For the thermometer-case mounted
under the fore stay, 2 thermometers were selected, for which
the corrections were under 0.°05.
In 1876, and pccasionally in 1877, I made
comparative experiments with a sling thermometer and with the dry
thermometer under the fore stay. The sling thermometer
was swung on the fore part of the roundhouse, at the same
height as the thermometer in its case under the fore stay.
The result of these experiments was as follows: —
Slyngetherm. (Sling Therm.) Corr. Tørt (Dry.) Therm. Forskjel. (Diff.) y
1876. Juni 20. 1« pm. 11.°8 12."2 — o.°4 180°
(June) 3°- O pm. 12. 4 12. 7 — 0.3 27
Juli 2. 7 pm. II. 7 12. 0 — 0.3 35
(July) 3- 7 pm. II. 2 11. 0 -f- 0. 2 IOI
„ „ 8 pm. 11. I 10. 8 + 0.3 102
„ 7- 10 piil. 10. 0 10. 0 0. 0 24
1877- Juni 14- 6 pm. • II- 3 11, i + 0. 2 45
(June) 15- 11 am. 9. 2 9. i + 0.1 0
* ig. 5 pm. 6. 6 6-5 + 0. i 22
Middel (Mean). —o.°oi
6*
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