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I 1877 fik jog til Foræring af Hr. .T. Y. Buchanan,
Clialleiigor-Expeditionens Cliomiker, et nyt
Dybvandsther-mometer af on ejendommelig Construction, som han
havde opfundet og provet paa denne Expedition, og hvilket
han kaldte Kviksølvpiezonieter. Uagtet kortelig beskrevet
af Hr. Buchanan1, maa jeg dog her give en Beskrivelse
af dette Instrument, da det var mig, navnlig i 1 <S7 7, men
ogsaa i 1878, til uvurderlig Nytte som Controlapparat
folde Miller-Casella’ske Dybvandsthermometres
Trykcorrec-tioner, foruden som et selvstændigt Dybvandsthermometer,
der aldrig kom i Uorden, og som tillod en større
Nøjagtighed i Temperaturens Bestemmelse end de ældre
Ther-mometre.
Figur 1 viser
Kviksolvpiezonie-tret i halv Maalestok. Det er, som
man ser, et Kviksölvthermometer, hvis
Beholder A er temmelig stor og ikke
beskyttet mod det ydre Tryk. Det
i Millimeter paa selve Glasset
inddelte Tlierinometerrør or ombøjet og
fyldt mod rent Vand fra B til C,
forresten med Kviksølv. Dets Ende
er aaben og udmunder i Koppen D,
der er fyldt med Kviksølv. Denne
Kop er kugleformet med en Hals,
der omslutter Thermonieterrørot. Et
Stykke Kautsehukslauge E fæster
Koppen til Roret. For at give
Vandet Adgang til at trykke paa
Kviksølvet i Koppen er Glasstangen eller
Glasrøret H stukket imellem
Ther-nioineterroret og Kautscliukslangen.
En magnetisk Index I af samme
Slags som Indexon i Miller-Casella’s
Thermometer, er indbragt i Vandet
over Kviksølvet. Tallene paa
Skalaen betegne Centimeter.
Instrumentet, er, ligesom det nævnte
Thermometer, fæstet til en Ebonitplade og
staar, naar det bruges, i et
Kobber-hylstor. Det er forfærdiget af
Ca-sella i London.
Instrumentet er saaledes
construeret, at dets Stand (den Aflæsning,
der svarer til Kviksølvtoppen C)
afhænger saavel af Temperaturen som
af Trykket. Dets Stand ved
forskjellige Temperaturer under almindeligt
Lufttryk bestemtes ved Sammenligning med
Normalther-momotret. En Temperaturvariation af 1° C svarer omtrent
In 1877, Mr. J. Y. Buchanan, Chemist to the Clial
longer Expedition, kindly presented mo with a. deep-sea
thermometer, of a new and peculiar construction, devised
by himself and tested on that Expedition, and which he
calls the Mercury-Piezometer. Though briefly described
by Mr. Buchanan,1 I must here append a description of
this instrument, since it proved in 1877, but also in 1878,
of incalculable advantage for controlling the
pressure-corrections of the Miller-Casolla deep-sea thermometers, not to
mention its use as an independent deep-sea thermometer,
that never got out of order and which admitted of greater
certainty and exactness in determining Ille temperature
than any of the older instruments.
Figure 1 represents the
mercury-piezometer, half size. Tt is, as
will at once be seen, a
mercury-thermometer- having the bulb A
comparatively large and not protected
against the outward pressure. The
stem, divided into millimetres on
the glass itself, is bent round and
filled with pure water from B to
C — for the rest, with mercury.
Its end is open and dips into the
cup, D, which is tilled with
mercury. Tilis cup is spherical in shape,
with a neck encircling the tube of
the thermometer. A piece of
india-rubber tubing, E, attaches the cup
to the glass stem. That the water
may have free admission to press upon
the mercury in the cup, the glass
rod or glass tube, H. is placed
between the Stem of the
thermometer and the india-rubber tubing. A
Magnetic Index, I, similar to the
index iu the Miller - Casella
thermometer, is introduced into the
water above the mercury. The
figures on the scale indicate
centimetres. As with the aforesaid
thermometer, this instrument is made
fast to an ebonite plate, and
the whole rests enclosed within a
copper ease. It was made by
Casella of London.
The instrument is constructed
in such a manner, that its reading
(the division that corresponds with
the top of the mercury, C) depends
alike on temperature and on
pressure. Its reading at different
temperatures under ordinary atmospheric pressure was
determined by comparison with the Standard-Thermometer.
Proceedings of the Royal Society lS7(i. S. Hi;?.
Proceedings of the Royal Society, I*
Fig. 1.
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