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36
üe sandsynligste Værdier for Coefficienterne blive
a = + 0.mm467, b = — 0.11157, c=-\- 0.06638, d = + 0.00292
og altsaa Formelen:
N= A + 0.mm47 — 0.1116 T + 0.0664 (760 — A) + 0.00291.
De efter denne Formel beregnede Værdier af N—A
ere opførte i ovenstaaende Tabel. Beregningen efter
Formelen er gjort ved Hjelp af en grafisk Tabel, paa hvilken
der med Argument A langs de horizontale Linier og
Argument T langs de verticale, ere optrukne Linier,
skraat-løbende, for Værdierne af a -f- b T -f- c (760 — A) for hver
Tiendedel Millimeter fra + l.mm4 til — 3.mm6. Af denne
Tabel kan saaledes den samlede Sum af disse Oorrectioner
udtages, og hertil lægges Correctionen dt, der er regnet
lig 0 fra 15de til og med 30te Juni, lig + 0.mml fra 1ste
Juli til 5te August, og lig + 0.",m2 fra 6te August til 16de
August. Denne sidste Correction udtrykker Forandringen
af Aneroidbarometrets constante Correction, der, under
Rejserne i 1877, ikke naaer op til 0.mn,2. Vi have nemlig
0.00292 X 62 = 0.18. Af Rubrikken Obs. — Ber. i
ovenstaaende Tabel beregnes Middelfejlen af en Sammenligning
mellem Søbarometret og Aneroidbarometret, begge
reducerede til sand Baro meterhøj de efter de angivne Methoder,
til ± 0.—177.
Den midlere "Fejl bliver e = + 0."""256.
Den sandsynlige Fejl „ d = + 0.mm170.
Den sandsynlige Fejl af en Sammenligning mellem
Søbarometret Adie 1493 og det meteorologiske Instituts
Normalbarometer er fundet lig + 0.mm063. Herefter skulde
den sandsynlige Fejl af en reduceret Observation af
Aneroidbarometret ombord blive omtrent + V(0.170)2 — (0.063)2
_ 0,"""158. Jeg tror, at man maa være tilfreds med at
kunne opnaa denne Nøjagtighed af Barometerobservationer
tilsøs. Den er visselig lige saa stor som den, man vilde
opnaa under gjennemsnitlige Vejrforhold med et Søbarometer,
da dette enten er trægt, eller, i uroligt Vejr, pumper.
For at undersøge, om der mellem Iagttagernes
(Styrmændenes) Aflæsninger af Aneroidbarometret og mine
Aflæsninger er nogen constant Forskjel eller personlig
Ligning, har jeg gaaet frem paa følgende Maade. De
Observationer af Aneroidbarometret, jeg har noteret i det o
venbeskrevne Øjemed, — for at controllere Aneroidbarometret —
paa de Dage, der gjordes Observationer ombord af
Styrmændene, har jeg reduceret paa ovenangivne Maade og
sammenstillet med Styrmændenes, i de meteorologiske Tabeller
nedenfor for hver Time givne. Efter disse timevise
Observationer var det ikke vanskeligt at interpolere
Styrmændenes Observation til det Klokkeslet, da jeg tog min
Observation. Resultatet af 40 saadanne Sammenstillinger er,
at Styrmændene i Gjennemsnit have noteret
Aneroidbarometret 0.mm045 lavere end jeg. Altsaa en umerkelig
Forskjel. Middeltallet af Afvigelse mellem Styrmændenes og
mine Aflæsninger er + 0.mm15, en Størrelse, der er næsten
ganske den samme som den ovenfor fundne sandsynlige Fejl
The most probable values for the coefficients, are
a= + 0.mm467, b = — 0.11157, c = + 0.06638, d = 0.00292;
and hence we have the formula: —
N=A -j- 0.mm47 — 0.1116 T+ 0.0664(760 — A) + 0.00291.
The values of N—A computed from this formula are
set forth in the above Table. The computation according
to the said formula was made by means of a diagrammatic
table, which, with the argument A along, the horizontal
lines, and the argument T along the vertical, gives a series
of lines — oblique — representing the values of a b T
c (760 — A) for every tenth of a millimetre, from -j- l.mm4
to — 3.fflm6. Hence, from this Table the whole sum of the
said corrections can be found, to which must be added the
correction dt, put =: 0 from the 15th to (and including) the
30th of June; = + 0.mmi from the 1st of July to the.5th
of August; and zz 0.mm2 from the 6th to the 16th of
August. The latter correction expresses the change in the
constant correction of the Aneroid barometer, which, on
the cruises in 1877, did not reach 0.mra2. For we have
0.00292 X 62 = 0.18. From the Column "Obs. — Comp.’’ in
the above Table, the mean error of a comparison between the
marine barometer and the Aneroid barometer, both reduced
to true barometric pressure b^f the methods previously
described, is computed at +. 0.""" L77.
The mean error becomes e = + 0."""250.
The probable error „ <)’:= +0.mm 170.
The probable error of a comparison between the
marine barometer Adie No. 1493 and the standard
barometer of the Meteorological Institute, has been found =
+ 0."’"’063. Hence, the probable error of a reduced
observation of the Aneroid barometer on board, should be about
+ V (0.170)* — (0.063)*= + 0.—158. This degree of
accuracy may, I think, be regarded as satisfactory. It is, at
least, quite equal to that attainable during average weather
with a marine barometer, which is anything but sensitive,
or, in boisterous weather, is given to pump.
With a view to investigate whether a constant
difference, or personal equation, actually exists between the
observers’ (the mates’) readings of the Aneroid barometer
and my own, I proceeded in the following manner: — The
observations of the Aneroid barometer — taken with the
object specified above, viz. to control that instrument —
which I have noted down on the days when observations
were made on board by the mates, I have reduced, as
described above, and compared with those of the mates,
entered in the Meteorological Tables given below for every
hour. From these hourly observations, it was not difficult
to interpolate the observations of the mates for the hour
when I took my observation. The result of 40 such
comparisons is, that the mates, on an average, have noted the
readings of the Aneroid barometer 0.fflffl045 lower than I
have done — a well-nigh inappreciable difference. The
mean difference between the indications read off by the
mates and by myself, is + 0.mm15, a value almost exactly
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