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(ct.-27, 1870 | 
NATURE 
515 
have been shown to do, two contemporaneous but dissimilar 
climates, separated only by a few miles horizontally and by 300 
fathoms vertically. 
But further : the Temperature-soundings taken in the Porcu- 
pine Expeditions of 1869 and 1870 have conclusively shown that 
a temperature as low as 36°5° prevails over the deeper parts of 
the North Atlantic sea-bed ; this reduction being due to the per- 
vasion of Arctic and Antarctic waters, which come to replace 
the superficial flow of Equatorial water (as in the Gulf Stream 
and other currents) towards the Polar areas. In conformity with 
this depression of temperature, many species of Mollusca, 
Crustacea, and Echinodermata, formerly supposed to be purely 
Arctic, have been found to range southwards in deep water as far 
as the Straits of Gibraltar ; and we have shown it to be highly 
probable that an extension of the same mode of exploration 
would bring them up from the abysses of even intertropical seas, 
ever which a similar climate prevails, and that an actual con- 
tinuity may thus be found to exist between the Arctic and the 
Antarctic Faunce. This idea was well put forth some years since 
by our excellent friend Prof. Lovén, of Stockholm, in his dis- 
cussion of the results of the deep-sea dredgings executed by the 
Swedish Spitzbergen Expedition of 1861, under Torell. ‘* Con- 
sidering,” he says, “‘the power of endurance in these lower 
marine animals, and recollecting the facts that properly Arctic 
species which live also on the coast of Europe, are generally 
found there at greater depths than in their proper home, and 
that certain Antarctic species very closely agree with Arctic 
species, the idea occurs that, while in our own seas and those of | 
warm climates, the surface, the coast line, and the lesser depths 
are peopled with a rich and varied Fauna, there exists in the 
great Atlantic depression, perhaps in all the abysses of our 
globe, and continued from Pole to Pole, a Fauna of the same 
general character, thriving under severe conditions, and approach- 
ing the surface where none but such exist in the coldest seas.” 
But whilst the question of Deep-sea Temperature is one of 
the greatest Biological interest, its determination is of even 
greater importance to the Geologist, as affecting his interpreta- 
tion of the phenomena on which his belief in a former general 
prevalence of a Glacial climate is founded. For if a Glacial 
temperature should be found now to prevail, and types of Animal 
life conformable thereto should prove to be diffused, over the 
deeper portion of the existing Sea-bed in all parts of the globe, 
it is obvious that the same may have been the case at any 
Geological epoch ; for there must have been deep seas in 
all periods, and the Physical forces which maintain the 
oceanic circulation at the present time must have been always 
in operation, though modified in their local action by the 
distribution of land and water existing at any particular 
date. And as the elevation of the present deep-sea bed of even 
the Intertropical oceanic area would (if we have correctly inter- 
preted the results of our own and others’ observations) offer to 
the study of the Geologist of the future a deposit characterised by 
the presence of Polar types, so must the Geologist of the present 
hesitate in regarding the occurrence of Boreal types in any 
marine deposit as adequate evidence fvr se of the general exten- 
sion of Glacial action into temperate or tropical regions. At 
any rate, it may be considered as having been now placed beyond 
reasonable doubt, that a Glacial Submarine climate may prevail 
over any area, without having any relation whatever to the 
Terrestrial climate of that area. 
These views are offered by us with the more confidence, since 
they are in harmony with the deductions already drawn by Geo- 
logists of eminence from facts observed by them. Thus I find 
on my return from the Mediterranean a letter from Principal 
Dawson, of Montreal, from which Iam sure he would permit 
me to make public the following extract :— 
«« |. . In reading your recent interesting publications on 
the Life of the Deep Sea, it occurred to me to mention to you 
that the fact which you have proved on the European coast, as 
to the existence and action of cold Arctic currents on the bottom 
of the ocean, was affirmed by me years ago for the American 
coast, on geological and geographical evidence, and was applied 
to the explanation of the Post-pliocene climate. On the Ame- 
rican coast we have the cold currents in shallower water than 
you haye now ; though in the Post-pliocene you had them in 
shallow water also. It is true that the Glacial theories of 
Agassiz and others have prevented the proper amount of atten- 
tion to these facts ; but I have insisted on them again and again, 
and fully believe that the varying distribution of the cold and 
warm currents, depending on the elevation and depression of the 
sea bottom, will account for most of the differences of climate 
indicated by fossils and boulders from the Laurentian to the 
Modern period. I have some new and unpublished facts on this 
subject, which I intend to bring out in connection with the work 
Tam now doing with the help of your brother, in the Post- 
pliocene geology of Canada.” 
In conclusion, I venture to anticipate that the words with 
which I concluded my lecture at the Royal Institution, ‘On the 
Results obtained in the Zighéning Expedition of 1868,” will be 
found to have been fully justified by those of the ‘‘ Porcupine 
Expeditions” of 1869 and 1870; and that whatever may be 
thought of the notion that ‘‘we are still living in the Cretaceous 
epoch,” we have furnished adequate proof that the formation of 
Glacial beds was not Imited to any special Geological period, 
but that they are now, and have been through all time, in course 
of deposition :—‘*The facts I have now brought before you, 
still more the speculations which I have ventured to connect 
with them, may seem to unsettle much that has been generally 
accredited in Geological Science, and thus to diminish rather than 
to augment our stock of positive knowledge; but this is the neces- 
sary result of the introduction of a new idea into any department 
of scientific inquiry. Like the flood which tests the security of 
every foundation that stands in the way of its onward 1ush, over- 
| throwing the house built only on the sand, but leaving unharmed 
the edifice which rests secure on the solid rock, so does a new 
method of research, a new series of facts, or a new application 
of facts previously known, come to bear with impetuous force 
on a whole fabric of doctrine, and subject it to an undermining 
power which nothing can resist, save that which rests on the 
solid rock of Truth. And it is here that the Moral value of 
Scientific study, pursued in a spirit worthy of its elevated aims, 
pre-eminently shows itself. For, as was grandly said by Schiller 
in his admirable contrast between the Trader in Science and 
the true Philosopher, ‘New discoveries in the field of his activity 
which depress the one, enrapture the other. Perhaps they fill a 
chasm which the growth of his ideas had rendered more wide 
and unseemly ; or they place the last stone, the only one want- 
ing, to the completion of the structure of his ideas. But even 
should they shiver it into ruins, should a new series of ideas, a 
new aspect of nature, a newly-discovered law in the physical 
world, overthrow the whole fabric of his knowledge. ze has 
always loved truth better than his system, and gladly will he ex- 
change her old and defective form for a new and fairer one.’” 
WILLIAM B, CARPENTER 
Ona Method of Ascertaining the Rate of Ascent of 
Fluid in Plants 
WHEN conducting a series of physiological experiments on the 
transpiration of fluid by leaves, it became a matter of import- 
ance to determine the rapidity of ascent of fluid. My colleague, 
Prof. Church, had suggested for another series of experiments 
the use of lithium citrate, a salt easily taken up by plants, and 
one which can be detected with the greatest readiness by means 
of the spectroscope. Preference was given to the citrate, because 
of its containing an organic acid, and on this account not likely 
to meet with any obstruction to its passage from the tissues. This 
method I have used with great success. In one experiment the 
fluid had risen nine inches in thirty minutes, in another five 
and a half inches in ten minutes. This method is greatly supe- 
rior to the use of colouring matters, which seem to experience 
considerable resistance in their passage through the vessels. Full 
particulars of these and numerous other experiments in the same 
direction will shortly be published. W. R. M‘Nas, M.D. 
Royal Agricultural College, Cirencester, Oct. 20 
The Aurora Borealis 
HavinG read the two accounts of Aurora Borealis in this 
week’s number of NATURE, I hope the following brief account 
of the very beautiful one that occurred here may not prove unin- 
teresting. On Friday, the 14th Oct. at 8.15 p.m., I noticed a 
bright appearance towards the north-west, somewhat resembling 
the moon rising, and on going to the front of the house which 
faced the north, saw that the whole of the horizon from west to 
south-east was lit up with a bluish white light. Gradually long 
streaks of the same colour stretched themselves up almost to the 
zenith, and then a blood-coloured light {ormed the higher por- 
tions, while the lower kept the bluish white colour already 
noticed. 
