- E.
[7] "This morning, 5th September, I let down a thermometer, suspended
in the middle of a strong wooden case, of such a construction as to
let the water pass freely through it in its descent, but which shut
close the instant it began to be drawn up. By this means the
thermometer was brought up in a body of water of the same heat with
that it had been let down to. The results were as above." - W.
This opportunity may be used for introducing the following table and
remarks, which are certainly deserving attention. "To ascertain the
degree of warmth of the sea-water, at a certain depth, several
experiments were made by us. The thermometer made use of, was of
Fahrenheit's construction, made by Mr Ramsden, and furnished with an
ivory scale; it was, on these occasions, always put into a cylindrical
tin case, which had at each end a valve, admitting the water as long
as the instrument was going down, and shutting while it was hauling up
again. The annexed table will at once shew the result of the
experiments.
| Degrees of Fahrenheit's | |Stay of |Time in|
| Thermometer. | |the |hauling|
| - - - - - - - - - - - - - | |Thermo- |the |
| |On the | |Depth |meter |Thermo-|
| In the |Surface |At a |in |in the |meter |
| Air. |of the |certain |Fathoms. |Deep. |up. |
Date |Latitude | |Sea. |Depth. | | | |
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
1772
Sept. 5 00 deg.52'N. 75 deg. 74 deg. 66 deg. 85 F. 30' 27-1/2'
Sept.27. 24 deg.44'S. 72-1/2 70 deg. 68 deg. 80 F. 15' 7'
Oct. 12. 34 deg.48'S. 60 deg. 59 deg. 58 deg. 100 F. 2O' 6'
Dec. 15. 55 deg.00'S. 30-1/2 deg. 30 deg. 34 deg. 100 F. 17' 5-1/2'
Dec. 23. 55 deg.26'S 33 deg. 32 deg. 34-1/2 deg. 100 F. 16' 6-1/2'
1773
Jan. 13. 61 deg.00'S. 37 deg. 33-1/2 deg. 32 deg. 100 F. 20' 7'
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
From this table it appears, that under the Line and near the tropics,
the water is cooler at a great depth than at its surface. In high
latitudes, the air is cooler sometimes, sometimes very near upon a
par, and sometimes warmer than the sea-water at the depth of about 100
fathoms, according as the preceding changes of the temperature of the
air, or the direction and violence of the wind happen to fall out. For
it is to be observed, that these experiments were always made when we
had a calm, or at least very little wind; because in a gale of wind,
we could not have been able to make them in a boat. Another probable
cause of the difference in the temperature of the sea-water in the
same high latitude, undoubtedly must be sought in the ice; in a sea
covered with high and extensive ice islands, the water should be
colder than in a sea which is at a great distance from any ice." - F.
This table is evidently too confined, and made up of too few elements,
to justify almost any general inferences. The subject is certainly a
curious one, and merits full investigation, but presents very
considerable difficulties, as many circumstances, which are likely to
modify the result, may escape notice during the experiments. It has
been said, that as water is most dense at from 37 to 39 Fahrenheit,
this may be presumed to be the mean temperature at the bottom of the
sea; but such hypothetical deductions are, perhaps, entitled to little
confidence. It may however be safely enough presumed, that the
temperature of the sea is kept tolerably uniform on the well-known
principle of statics, that the heavier columns of any fluid displace
those that are lighter. The waters of the ocean, perhaps, are the
great agent by which the average temperature of our globe is preserved
almost entirely invariable. We shall have an opportunity, in the
account of another voyage, to make some remarks on this subject, and
to notice more exact experiments than those just now mentioned. - E.
[8] "On this day, we had an alarm that one of our crew was overboard,
upon which we immediately put about, but seeing nothing, the names of
all persons on board the vessel were called over, and none found
missing, to our great satisfaction. Our friends on board the
Adventure, whom we visited a few days after, told us they had indeed
suspected by our manoeuvre, the accident which we had apprehended, but
that looking out on the sea, Captain Furneaux had plainly observed a
sea-lion, that had been the cause of this false alarm." - G.F.
[9] Mr G.F. concludes his description of this well-known appearance in
the following very just remark: "There was a singularity, and a
grandeur in the display of this phenomenon, which could not fail of
giving occupation to the mind, and striking it with a reverential awe,
due to Omnipotence. The ocean covered to a great extent, with myriads
of animalcules; these little beings, organized, alive, endowed with
locomotive power, a quality of shining whenever they please, and
illuminating every body with which they come in contact, and of laying
aside their luminous appearance at pleasure; all these ideas crowded
upon us, and bade us admire the Creator, even in his minutest works."
However florid the language of this gentleman on the subject, his
account and opinions are strongly enforced by the recent discoveries
of the French naturalists related by Mr Peron, to which we shall
probably call the reader's attention hereafter. - E.
[10] Mr G.F. speaks with much more enthusiasm, as one might have
expected, of Dr Sparrman, extolling his talents and activity in the
course of science, but lamenting, at the same time, that this voyage,
on which he now set out, yielded much less matter for observation than
his ardent mind had anticipated.
