Sir H. Davy's paper on the Phenomena of Volcanoes.--His
experiments on Vesuvius.--Theory of Volcanic action.--His
reception abroad.--Anecdotes.--His last letter to Mr.
Poole from Rome.--His paper on the Electricity of the
Torpedo.--Consolations in Travel, or the Last Days of a
Philosopher.--Analysis of the work.--Reflections suggested by
its style and composition.--Davy and Wollaston compared.--His
last illness.--Arrival at Geneva.--HIS DEATH.
A short time before Sir Humphry Davy quitted England, to which he
was destined never to return, he communicated to the Royal Society
a paper "On the Phenomena of Volcanoes;" which was read on the 20th
of March 1828, and published in the Transactions of that year.
The object of this memoir was to collect and record the various
observations and experiments which he had made on Vesuvius,
during his several visits to that volcano. The appearances which
it presented in 1814 and 1815 have been already noticed; it was
in December 1819, and during the two succeeding months, that
the mountain offered a favourable opportunity for making those
experiments which form the principal subject of the present
communication.
It was a point of great importance to determine whether any
combustion was going on at the moment the lava issued from the
mountain; for this fact being once discovered, and the nature of
the combustible matter ascertained, we should gain an immense step
towards a just theory of the sources of volcanic action. For this
purpose, he carefully examined both the lava and the elastic fluids
with which it was accompanied. He was unable, however, to detect
any thing like deflagration with nitre, which must have taken place
had the smallest quantity of carbonaceous matter been present; nor
could he, by exposing the ignited mass to portions of atmospheric
air, discover that any appreciable quantity of oxygen had been
absorbed. On immersing fused lava in water, no decomposition of
that fluid followed, so that there could not have existed any
quantity of the metallic bases of the alkalies or earths. Common
salt, chloride of iron, the sulphates and muriates of potash, and
soda, generally constituted the mass of solid products; while
steam, muriatic acid fumes, and occasionally sulphurous acid
vapours, formed the principal elastic matters disengaged.
He informs us it was on the 26th of January 1820, that he had the
honour to accompany his Royal Highness the Prince of Denmark in an
excursion to the mountain, on which occasion his friend, Cavalier
Monticelli, was also present. At this time, the lava was seen
nearly white hot through a chasm near the place where it flowed
from the mountain; and yet, although he threw nitre upon it in
large quantities through this chasm, there was no more increase
of ignition than when the experiment was made on lava exposed to
the free air. He observed that the appearance of the sublimations
was very different from that which they had presented on former
occasions; those near the aperture were coloured green and blue
by salt of copper; but there was, as usual, a great quantity of
muriate of iron. On the 5th, the sublimate of the lava was pure
chloride of sodium; in the sublimate of January 6th, there were
both sulphate of soda and indications of sulphate of potash; but in
those which he collected during this last visit, the sulphate of
soda was in much larger quantities, and there was much more of a
salt of potash.
For nearly three months the craters, of which there were two, were
in activity. The larger one threw up showers of ignited ashes and
stones to a height apparently of from two hundred to two hundred
and fifty feet; and from the smaller crater steam arose with great
violence. Whenever the crater could be approached, it was found
incrusted with saline matter: and the walk to the edge of the small
crater, on the 6th of January, was through a mass of loose saline
matter, principally common salt coloured by muriate of iron, in
which the foot sunk to some depth. It was easy, even at a great
distance, to distinguish between the steam disengaged by one of the
craters, and the earthy matter thrown up by the other. The steam
appeared white in the day, and formed perfectly white clouds, which
reflected the morning and evening light of the purest tints of red
and orange. The earthy matter always appeared as a black smoke,
forming dark clouds, and in the night it was highly luminous at the
moment of the explosion.
He concludes this paper on Volcanoes with some observations on
the theory of their phenomena. "It appears," says he, "almost
demonstrable, that none of the chemical causes anciently assigned
for volcanic fires can be true. Amongst these, the combustion
of mineral coal is one of the most current; but it seems wholly
inadequate to account for the phenomena. However large the stratum
of pit-coal, its combustion under the surface could never produce
violent and excessive heat; for the production of carbonic
acid gas, when there was no free circulation of air, must tend
constantly to impede the process: and it is scarcely possible
that carbonaceous matter, if such a cause existed, should not be
found in the lava, and be disengaged with the saline or aqueous
products from the bocca or craters. There are many instances in
England of strata of mineral coal which have been long burning; but
the results have been merely baked clay and schists, and it has
produced no result similar to lava.
"If the idea of Lemery were correct, that the action of sulphur on
iron may be a cause of volcanic fires, sulphate of iron ought to
be the great product of the volcano; which is known not to be the
case; and the heat produced by the action of sulphur on the common
metals is quite inadequate to account for the appearances. When
it is considered that volcanic fires occur and intermit with all
the phenomena that indicate intense chemical action, it seems not
unreasonable to refer them to chemical causes. But for phenomena
upon such a scale, an immense mass of matter must be in activity,
and the products of the volcano ought to give an idea of the
nature of the substances primarily active. Now, what are these
products? Mixtures of the earths in an oxidated and fused state,
and intensely ignited; water and saline substances, such as might
be furnished by the sea and air, altered in such a manner as might
be expected from the formation of fixed oxidated matter. But it may
be said, if the oxidation of the metals of the earths be the causes
of the phenomena, some of these substances ought occasionally to
be found in the lava, or the combustion ought to be increased
at the moment the materials passed into the atmosphere. But the
reply to this objection is, that it is evident that the changes
which occasion volcanic fires take place in immense subterranean
cavities; and that the access of air to the acting substances
occurs long before they reach the exterior surface.
"There is no question but that the ground under the solfaterra
is hollow; and there is scarcely any reason to doubt of a
subterraneous communication between this crater and that of
Vesuvius: whenever Vesuvius is in an active state, the solfaterra
is comparatively tranquil. I examined the bocca of the solfaterra
on the 21st of February 1820, two days before the activity of
Vesuvius was at its height: the columns of steam which usually
arise in large quantities when Vesuvius is tranquil, were now
scarcely visible, and a piece of paper thrown into the aperture
did not rise again; so that there was every reason to suppose
the existence of a descending current of air. The subterraneous
thunder heard at such great distances under Vesuvius is almost a
demonstration of the existence of great cavities below filled with
aëriform matter: and the same excavations which, in the active
state of the volcano, throw out, during so great a length of time,
immense volumes of steam, must, there is every reason to believe,
in its quiet state, become filled with atmospheric air.[115]
[115] "Vesuvius is a mountain admirably fitted, from its form and
situation, for experiments on the effect of its attraction on
the pendulum: and it would be easy in this way to determine the
problem of its cavities. On Etna the problem might be solved on a
larger scale."
"To what extent subterraneous cavities may exist, even in common
rocks, is shown in the limestone caverns of Carniola, some of
which contain many hundred thousand cubical feet of air; and in
proportion as the depth of an excavation is greater, so is the air
more fit for combustion.
"The same circumstances which would give alloys of the metals of
the earths the power of producing volcanic phenomena, namely, their
extreme facility of oxidation, must likewise prevent them from
ever being found in a pure combustible state in the products of
volcanic eruptions; for before they reach the external surface,
they must not only be exposed to the air in the subterranean
cavities, but be propelled by steam; which must possess, under the
circumstances, at least the same facility of oxidating them as
air. Assuming the hypothesis of the existence of such alloys of
the metals of the earths as may burn into lava in the interior,
the whole phenomena may be easily explained from the action of the
water of the sea and air on those metals; nor is there any fact, or
any of the circumstances which I have mentioned in the preceding
part of this paper, which cannot be easily explained according to
that hypothesis. For almost all the volcanoes in the old world of
considerable magnitude are near, or at no considerable distance
from the sea: and if it be assumed that the first eruptions are
produced by the action of sea-water upon the metals of the earths,
and that considerable cavities are left by the oxidated metals
thrown out as lava, the results of their action are such as might
be anticipated; for, after the first eruptions, the oxidations
which produce the subsequent ones may take place in the caverns
below the surface; and when the sea is distant, as in the volcanoes
of South America, they may be supplied with water from great
subterranean lakes, as Humboldt states that some of them throw up
quantities of fish.
"On the hypothesis of a chemical cause for volcanic fires, and
reasoning from known facts, there appears to me no other adequate
source than the oxidation of the metals which form the bases of the
earths and alkalies; but it must not be denied, that considerations
derived from thermometrical experiments on the temperature of mines
and of sources of hot water, render it probable that the interior
of the globe possesses a very high temperature: and the hypothesis
of the nucleus of the globe being composed of fluid matter offers a
still more simple solution of the phenomena of volcanic fires than
that which has been just developed."
It must be admitted that the concluding sentence of this memoir
is rather equivocal. He states that the metalloidal theory of
volcanoes is most chemical, but that the hypothesis which assumes
the high temperature of the interior of the globe is the most
simple; but he leaves us in doubt as to his own belief upon the
subject. In his "Last Days," however, we shall find that he offers
a less reserved opinion upon this question.
* * * * *
With respect to Sir Humphry Davy's last journey to Rome, I have
nothing of particular interest to relate. Universally known
and respected, a member of almost every scientific society in
Europe, there was not a part of the Continent in which he felt
as a stranger in a foreign land. I might, in addition to the
circumstances which have been already mentioned, relate several
anecdotes in proof of the widely-extended popularity which
his genius and discoveries had secured for him. The following
striking incidents deserve particular notice.--Whilst sporting
in Austria, he was assaulted by some peasants; and the outrage
was no sooner made known to the Emperor, than he expressed his
sorrow and indignation in the strongest language, and immediately
directed that a party of troops should surround the district, and
a most rigorous search be made for the culprits. The search was
of course successful, and the "Carinthian boors" received merited
chastisement.
For the following anecdote I am indebted to Lady Davy. Her Ladyship
was travelling alone, on account of ill health, and upon arriving
at Basle, she naturally felt a strong desire to visit its far-famed
library; it so happened, however, that Sunday was the only day
which afforded her this opportunity, and so strictly is the sabbath
observed at that place, that she was at once informed that an
admission to the library, under any circumstances, was altogether
impossible. She nevertheless addressed a note to the librarian,
stating to him her name, and the reasons for her unusual request.
He immediately returned an answer, and appointed the hour of ten
for her visit. Having shown her all that deserved inspection, he
concluded his attentions by saying, "Madam, I have held the keys
of this library for thirty years, during which period only three
persons have been admitted to see its treasures on the Sunday;
two of these were crowned heads, the third the wife of the most
celebrated philosopher in Europe."
The following is the last letter which Davy ever wrote to his
much-valued friend Mr. Poole.--
TO THOMAS POOLE, ESQ.
MY DEAR POOLE, Rome, Feb. 6, 1829.
I have not written to you during my absence from England,
because I had no satisfactory account of any marked progress
towards health to give you, and the feelings of an invalid are
painful enough for himself, and should, I think, never form a
part of his correspondence; for they are not diminished by the
conviction that they are felt by others. Would I were better! I
would then write to you an agreeable letter from this glorious
city; but I am here _wearing away_ the winter; a ruin amongst
ruins! I am anxious to hear from you,--very anxious, so pray
write to me with this address, "Sir H. Davy, Inglese, posta
restanti, Rovigo, Italia." You know you must pay the postage
to the frontier, otherwise the letters, like one a friend sent
to me, will go back to you. Pray be so good as to be particular
in the direction,--the "Inglese" is necessary. I hope you got a
copy of my little trifle "_Salmonia_." I ordered copies to be
sent to you, to Mr. W----, and to Mr. Baker: but as the course
of letters in foreign countries is uncertain, I am not sure you
received them; if not, you will have lost little; a _second
edition_ will soon be out, which will be in every respect more
worthy of your perusal, being, I think, twice (not saying much
for it) as entertaining and philosophical. I will take care by
early orders that you have this book. I write and philosophize
a good deal, and have nearly finished a work with a higher
aim than the little book I speak of above, and which I shall
dedicate to you. It contains the essence of my philosophical
opinions, and some of my poetical reveries. It is, like the
"Salmonia," an amusement of my sickness; but "_paulo majora
canamus_." I sometimes think of the lines of Waller, and seem
to feel their truth:
"The soul's dark cottage, batter`d and decay'd,
Lets in new lights through chinks that Time has made."
I have, notwithstanding my infirmities, attended to scientific
objects whenever it was in my power, and I have sent the Royal
Society a paper which they will publish, on the peculiar
Electricity of the Torpedo, which I think bears remotely
upon the functions of life. I attend a good deal to Natural
History, and I think I have recognised in the Mediterranean
a _new species of eel_, a sort of link between the conger
and the muræna of the ancients. I have no doubt Mr. Baker is
right about the distinction between the conger and the common
eel. I am very anxious to hear what he thinks about _their
generation_. Pray get from him a distinct opinion on this
subject. I am at this moment getting the _eels in the markets_
here dissected, and have found _ova_ in plenty. Pray tell me
particularly what Mr. Baker has done; this is a favourite
subject with me, and you can give me no news so interesting.
My dear friend, I shall never forget your kindness to me. You,
with one other person, have given me the little happiness I
have enjoyed since my severe visitation.
I fight against sickness and fate, believing I have still
duties to perform, and that even my illness is connected in
some way with my being made useful to my fellow-creatures. I
have this conviction full on my mind, that intellectual beings
spring from the same breath of Infinite Intelligence, and
return to it again, but by different courses. Like rivers, born
amidst the clouds of heaven, and lost in the deep and eternal
ocean--some in youth, rapid and short-lived torrents; some in
manhood, powerful and copious rivers; and some in age, by a
winding and slow course, half lost in their career, and making
their exit through many sandy and shallow mouths. I hope to
be at Rovigo about the first week in April. I travel slowly
and with my own horses. If you will come and join me there, I
can give you a place in a comfortable carriage, and can show
you the most glorious country in Europe--Illyria and Styria,
and take you to the French frontier before the beginning
of autumn,--perhaps to England. If you can come, do so at
once. I have two servants, and can accommodate you with every
thing. I think of taking some baths before I return, in Upper
Austria; but I write as if I were a strong man, when I am like
a pendulum, as it were, swinging between death and life.
God bless you, my dear Poole.
Your grateful and affectionate friend,
H. DAVY.
Pray remember me to our friends at Stowey.
His paper on the Electricity of the Torpedo, to which he alludes in
the foregoing letter, appears to have been written shortly after he
had finished his "Salmonia," as it is dated from Lubiana, Illyria,
on the 24th of October, and it was read before the Royal Society
on the 20th of November 1828, and published in the first part of
the Transactions for 1829. It will be remembered, that this subject
had long engaged his attention; and he expresses his surprise that
the electricity of living animals should not have been an object of
greater attention, both on account of its physiological importance,
and its general relation to the science of electro-chemistry.
When Volta discovered his wonderful pile, he imagined he had made
a perfect resemblance of the organ of the Gymnotus and Torpedo;
and Davy observes, that whoever has felt the shocks of the natural
and artificial instruments must have been convinced, as far as
sensation is concerned, of their strict analogy.
After the discovery of the _chemical_ power of the Voltaic
instrument, he was naturally desirous of ascertaining whether this
property was possessed by the electrical organs of living animals;
for which purpose, he instituted various experiments, but he could
not discover that such was the fact. Upon mentioning his researches
to Signor Volta, with whom he passed some time in the summer of
1815, the Italian philosopher showed him a peculiar form of his
instrument, which appeared to fulfil the conditions of the organs
of the torpedo; _viz._ a pile, of which the fluid substance was
a very imperfect conductor, such as honey or a strong saccharine
extract, which required a certain time to become charged, and which
did not decompose water, though it communicated weak shocks.
The discovery by Oersted of the effects of Voltaic electricity on
the magnetic needle induced Davy to examine whether the electricity
of living animals possessed a similar power. Having, after some
trouble, procured two lively and recently caught Torpedoes, he
passed the shocks from the largest of these animals a number
of times through the circuit of an extremely delicate magnetic
electrometer, but, although every precaution was used, not the
slightest deviation of, or effect on, the needle could be perceived.
"These negative results," says he, "may be explained by supposing
that the motion of the electricity in the torpedinal organ is in
no measurable time, and that a current of some continuance is
necessary to produce the deviation of the magnetic needle; and I
found that the magnetic electrometer was equally insensible to the
weak discharge of a Leyden jar as to that of the torpedinal organ;
though whenever there was a continuous current from the smallest
surfaces in Voltaic combinations of the weakest power, but in which
some chemical action was going on, it was instantly and powerfully
affected. Two series of zinc and silver, and paper moistened in
salt and water, caused the permanent deviation of the needle
several degrees, though the plates of zinc were only one-sixth of
an inch in diameter.
"It would be desirable to pursue these enquiries with the
electricity of the Gymnotus, which is so much more powerful than
that of the Torpedo; but if they are now to be reasoned upon,
they seem to show a stronger analogy between common and animal
electricity, than between Voltaic and animal electricity; it is
however, I think, more probable that animal electricity will be
found of a distinctive and peculiar kind.
"Common electricity is excited upon non-conductors, and is readily
carried off by conductors and imperfect conductors. Voltaic
electricity is excited upon combinations of perfect and imperfect
conductors, and is only transmitted by perfect conductors, or
imperfect conductors of the best kind.
"Magnetism, if it be a form of electricity, belongs only to perfect
conductors; and, in its modifications, to a peculiar class of them.
"The animal electricity resides only in the imperfect conductors
forming the organs of living animals, and its object in the economy
of nature is to act on living animals.
"Distinctions might be established in pursuing the various
modifications or properties of electricity in these different
forms; but it is scarcely possible to avoid being struck by another
relation of this subject. The torpedinal organ depends for its
powers upon the will of the animal. John Hunter has shown how
copiously it is furnished with nerves. In examining the columnar
structure of the organ of the Torpedo, I have never been able to
discover arrangements of different conductors similar to those in
galvanic combinations, and it seems not improbable that the shock
depends upon some property developed by the action of the nerves.
"To attempt to reason upon any phenomena of this kind as dependent
upon a specific fluid would be wholly vain. Little as we know of
the nature of electrical action, we are still more ignorant of
the nature of the functions of the nerves. There seems, however,
a gleam of light worth pursuing in the peculiarities of animal
electricity,--its connexion with so large a nervous system, its
dependence upon the will of the animal, and the instantaneous
nature of its transfer, which may lead, when pursued by adequate
enquirers, to results important for physiology."
He concludes this paper by expressing his fear that the weak state
of his health will prevent him from following the subject with the
attention it seems to deserve; and he therefore communicates these
imperfect trials to the Royal Society, in the hope that they may
lead to more extensive and profound researches.
We come now to the consideration of the last production of
his genius--"Consolations in Travel, or the Last Days of a
Philosopher:" A work which, he informs us in the preface, was
composed immediately after Salmonia, under the same unfavourable
and painful circumstances, and at a period when his constitution
suffered from new attacks. From this exercise of the mind, he
tells us, that he derived some pleasure and some consolation,
when most other sources of consolation and pleasure were closed
to him; and he ventures to hope that those hours of sickness may
be not altogether unprofitable to persons in perfect health. His
brother, Dr. Davy, who edited the work after the decease of Sir
Humphry, informs us that it was concluded at the very moment of the
invasion of the author's last illness, and that, had his life been
prolonged, it is probable some additions and some changes would
have been made.
"The characters of the persons of the dialogue," continues the
Editor, "were intended to be ideal, at least in great part;--such
they should be considered by the reader; and it is to be hoped,
that the incidents introduced, as well as the persons, will be
viewed only as subordinate and subservient to the sentiments and
the doctrines. The dedication, it may be specially noticed, is
the Author's own, and in the very words dictated by himself at a
time when he had lost the power of writing, except with extreme
difficulty, owing to the paralytic attack, although he retained in
a very remarkable manner all his mental faculties unimpaired and
unclouded." The words of the Dedication are "TO THOMAS POOLE, ESQ.
of Nether Stowey; in remembrance of thirty years of continued and
faithful friendship."
This is a most extraordinary and interesting work: extraordinary,
not only from the wild strength of its fancy, and the extravagance
of its conceptions, but from the bright light of scientific truth
which is constantly shining through its metaphorical tissue, and
irradiating its most shadowy imaginings. It may be compared to the
tree of the lower regions in the Æneid, to every leaf of which was
attached a dream; and yet, however wildly his fancy may dream, his
philosophy never sleeps; and in his exit from the land of phantoms,
the author can in no instance be accused of having mistaken the
gate of ivory for that of horn. To the biographer, the work is of
the highest interest and value, by confirming, in a remarkable
manner, the opinion so frequently expressed in the course of these
memoirs, with respect to the diversified talents of Sir Humphry
Davy; and above all, by elucidating that rare combination of
imagination with judgment, which imparted to his genius its more
striking peculiarities.
The work consists of six Dialogues:--1. THE VISION; 2. DISCUSSIONS
CONNECTED WITH THE VISION IN THE COLOSÆUM; 3. THE UNKNOWN; 4. THE
PROTEUS, OR IMMORTALITY; 5. THE CHEMICAL PHILOSOPHER; and 6. POLA,
OR TIME.
The interlocutors of the first dialogue are two intellectual
Englishmen, one of whom the author calls _Ambrosio_; a man of
highly cultivated taste, great classical erudition, and minute
historical knowledge: a Catholic in religion, but so liberal in
his sentiments, that in another age he might have been secretary
to Ganganelli. The other friend, whom he calls _Onuphrio_, was
a man of a very different character: belonging to the English
aristocracy, he had some of the prejudices usually attached to
birth and rank; but his manners were gentle, his temper good, and
his disposition amiable. Having been partly educated at a northern
university in Britain, he had adopted views in religion which went
even beyond toleration, and which might be regarded as entering the
verge of scepticism. For a patrician, he was very liberal in his
political views. His imagination was poetical and discursive, his
taste good, and his tact extremely fine,--so exquisite, indeed,
that it sometimes approached to morbid sensibility, and disgusted
him with slight defects, and made him keenly sensible of small
perfections to which common minds have been indifferent.
The author, with these his two friends, makes an excursion to the
Colosæum, and the conversation, which a view of those magnificent
ruins produced, together with the account of a dream, or vision,
which occurred to him while left alone amidst these mouldering
monuments, forms the subject-matter of the first dialogue. It is
impossible for any person of the least imagination to contemplate
this decay of former magnificence without strong emotion; but the
direction and tone of such feeling will be necessarily modified by
the qualities of the mind in which it is excited; and the author
has therefore very properly assigned to each of the _dramatis
personæ_, such opinions as might best correspond with his character
and temperament.
They are all represented as being struck with the transiency
of human monuments; but _Ambrosio_ views with triumph the
sanctifying influence of a few crosses planted around the ruins, in
arresting the farther decay of the pile. "Without the influence
of Christianity," he exclaims, "these majestic ruins would have
been dispersed or levelled to the dust. Plundered of their lead
and iron by the barbarians, Goths and Vandals, and robbed even of
their stones by Roman princes--the Barberini, they owe what remains
of their relics to the sanctifying influence of that faith which
has preserved for the world all that was worth preserving, not
merely arts and literature, but likewise that which constitutes
the progressive nature of intellect, and the institutions which
afford to us happiness in this world, and hopes of a blessed
immortality in the next." And he continues,--"What a contrast the
present application of this building, connected with holy feelings
and exalted hopes, is to that of the ancient one, when it was used
for exhibiting to the Roman people the destruction of men by wild
beasts, or of men more savage than wild beasts by each other, to
gratify a horrible appetite for cruelty, founded upon a still more
detestable lust, that of universal domination! And who would have
supposed, in the time of Titus, that a faith, despised in its
insignificant origin, and persecuted from the supposed obscurity
of its founder and its principles, should have reared a dome to
the memory of one of its humblest teachers, more glorious than
was ever framed for Jupiter or Apollo in the ancient world, and
have preserved even the ruins of the temples of the Pagan deities,
and have burst forth in splendour and majesty, consecrating truth
amidst the shrines of error, employing the idols of the Roman
superstition for the most holy purposes, and rising a bright and
constant light amidst the dark and starless night which followed
the destruction of the Roman empire!"
It was not to be expected that _Onuphrio_, whose views are
represented as verging upon scepticism, should have tacitly
coincided in these opinions of _Ambrosio_. He admits, indeed, that
some little of the perfect state in which these ruins exist may
have been owing to the causes just described; but these causes,
he maintains, have only lately begun to operate, and the mischief
was done before Christianity was established at Rome. "Feeling
differently on these subjects," says he, "I admire this venerable
ruin rather as the record of the destruction of the power of
the greatest people that ever existed, than as a proof of the
triumph of Christianity; and I am carried forward, in melancholy
anticipation, to the period when even the magnificent dome of St.
Peter's will be in a similar state to that in which the Colosæum
now is, and when its ruins may be preserved by the sanctifying
influence of some new and unknown faith; when perhaps the statue
of Jupiter, which at present receives the kiss of the devotee, as
the image of St. Peter, may be employed for another holy use, as
the personification of a future saint or divinity; and when the
monuments of the Papal magnificence shall be mixed with the same
dust as that which now covers the tombs of the Cæsars.
"Such, I am sorry to say, is the general history of all the works
and institutions belonging to humanity. They rise, flourish, and
then decay and fall; and the period of their decline is generally
proportional to that of their elevation. In ancient Thebes or
Memphis, the peculiar genius of the people has left us monuments
from which we can judge of their arts, though we cannot understand
the nature of their superstitions. Of Babylon and of Troy, the
remains are almost extinct; and what we know of those famous cities
is almost entirely derived from literary records. Ancient Greece
and Rome we view in the few remains of their monuments; and the
time will arrive when modern Rome shall be what ancient Rome now
is; and ancient Rome and Athens will be what Tyre or Carthage now
are, known only by coloured dust in the desert, or coloured sand,
containing the fragments of bricks, or glass, washed up by the wave
of a stormy sea."
For this desponding view of passing events, _Onuphrio_ finds
consolation in the evidences of revealed religion. In the origin,
progress, elevation, decline, and fall of the empires of antiquity,
he sees proofs that they were intended for a definite end in the
scheme of human redemption; and he finds prophecies which have been
amply verified. He regards the foundation or the ruin of a kingdom,
which appears in civil history so great an event, as comparatively
of small moment in the history of man and in his religious
institutions. He considers the establishment of the worship of one
God amongst a despised and contemned people, as the most important
circumstance in the history of the early world. He regards the
Christian dispensation as naturally arising out of the Jewish, and
the doctrines of the Pagan nations all preparatory to the triumph
and final establishment of a creed fitted for the most enlightened
state of the human mind, and equally adapted to every climate and
every people.
We cannot but regard these passages with great interest, as
indicating the train of thought which must have occupied the mind
of their author, and as proving that, in his latter days, he
not only studied the doctrines of Christianity, but derived the
greatest consolation from its tenets.
After some farther conversation, _Onuphrio_ and _Ambrosio_ leave
their friend the author to pursue his meditations amidst the
solitude of the ruins.
Seated in the moonshine on one of the steps leading to the seats
supposed to have been occupied by the patricians in the Colosæum
at the time of the public games, the train of ideas in which he
had before indulged continued to flow with a vividness and force
increased by the stillness and solitude of the scene, and by the
full moon, which, he observes, has always a peculiar effect on
these moods of feeling in his mind, giving to them a wildness and
a kind of indefinite sensation, such as he supposes belong at all
times to the true poetical temperament.
"It must be so," thought he, "no new city will rise again out of
the double ruins of this; no new empire will be founded upon these
colossal remains of that of the old Romans. The world, like the
individual, flourishes in youth, rises to strength in manhood,
falls into decay in age; and the ruins of an empire are like the
decrepid frame of an individual, except that they have some tints
of beauty, which nature bestows upon them. The sun of civilization
arose in the East, advanced towards the West, and is now at its
meridian; in a few centuries more, it will probably be seen sinking
below the horizon, even in the new world; and there will be left
darkness only where there is a bright light, deserts of sand
where there were populous cities, and stagnant morasses where the
green meadow, or the bright corn-field once appeared. Time," he
exclaimed, "which purifies, and, as it were, sanctifies the mind,
destroys and brings into utter decay the body; and even in nature
its influence seems always degrading. She is represented by the
poet as eternal in her youth; but amongst these ruins she appears
to me eternal in her age, and here, no traces of renovation appear
in the ancient of days."
He had scarcely concluded this ideal sentence, when his reverie
became deeper, and his imagination called up a spirit, who, having
rebuked him for his ignorance and presumption, undeceives him in
his views of the history of the world, by unfolding to him in
a vision the progress of man from a state of barbarity to that
of high civilization. He is first shown a country covered with
forests and marshes; wild animals were grazing in large savannahs,
and carnivorous beasts, such as lions and tigers, occasionally
disturbing and destroying them. Man appeared as a naked savage,
feeding upon wild fruits, or devouring shell-fish, or fighting
with clubs for the remains of a whale which had been thrown upon
the shore. His habitation was a cave in the earth--"See the birth
of Time!" exclaimed the Genius; "look at man in his newly-created
state, full of youth and vigour. Do you see aught in this state to
admire or envy?"
In the next scene, a country opened upon his view, which appeared
partly wild and partly cultivated; and men were seen covered with
the skins of animals, and driving cattle to enclosed pastures;
others were reaping and collecting corn, and others again were
making it into bread. Cottages appeared furnished with many of the
conveniences of life. The Genius now said, "Look at these groups
of men who are escaped from the state of infancy; they owe their
improvement to a few superior minds still amongst them. That aged
man whom you see with a crowd around him taught them to build
cottages; from that other they learnt to domesticate cattle; from
others, to collect and sow corn and seeds of fruit. And these arts
will never be lost; another generation will see them more perfect.
You shall be shown other visions of the passages of time; but as
you are carried along the stream which flows from the period of
creation to the present moment, I shall only arrest your transit
to make you observe some circumstances which will demonstrate
the truths I wish you to know." He then proceeds to describe in
succession the different scenes as they appeared before him, and to
relate the observations by which his genius, or intellectual guide,
accompanied him.
A great extent of cultivated plains, large cities on the sea-shore,
palaces, forums, and temples, were displayed before him. He saw men
associated in groups, mounted on horses, and performing military
exercises; galleys moved by oars on the ocean; roads intersecting
the country covered with travellers, and containing carriages
moved by men or horses. The Genius now said, "You see the early
state of civilization of man: the cottages of the last race you
beheld have become improved into stately dwellings, palaces, and
temples, in which use is combined with ornament. The few men to
whom, as I said before, the foundations of these improvements were
owing, have had divine honours paid to their memory. But look at
the instruments belonging to this generation, and you will find
they were only of brass. You see men who are talking to crowds
around them, and others who are apparently amusing listening groups
by a kind of song or recitation; these are the earliest bards and
orators; but all their signs of thought are oral, for written
language does not yet exist."
The Genius next presented to him a scene of varied business and
imagery. He saw a man who bore in his hands the same instruments
as our modern smiths, presenting a vase, which appeared to be made
of iron, amidst the acclamations of an assembled multitude; and he
saw in the same place men who carried rolls of papyrus in their
hands, and wrote upon them with reeds containing ink, made from
the soot of wood mixed with a solution of glue.--"See," the Genius
said, "an immense change produced in the condition of society by
the two arts of which you now see the origin; the one, that of
rendering iron malleable, which is owing to a single individual,
an obscure Greek; the other, that of making thought permanent in
written characters,--an art which has gradually arisen from the
hieroglyphics which you may observe on yonder pyramids. You will
now see human life more replete with power and activity."
In the scenes that succeeded, he saw bronze instruments thrown
away; malleable iron converted into hard steel, and applied to
a thousand purposes of civilized life; bands of men traversing
the sea, founding colonies, building cities, and, wherever they
established themselves, carrying with them their peculiar arts. He
saw the Roman world succeeded by cities filled with an idle and
luxurious population, and the farms which had been cultivated by
warriors, who left the plough to take the command of armies, now
in the hands of slaves; and the militia of free men supplanted by
bands of mercenaries, who sold the Empire to the highest bidder.
He saw immense masses of warriors collecting in the North and
East, carrying with them no other proofs of cultivation but their
horses and steel arms. He saw these savages every where plundering
cities and destroying the monuments of arts and literature. Ruin,
desolation, and darkness were before him, and he closed his eyes
to avoid the melancholy scene. "See," said the Genius, "the
termination of a power believed by its founders invincible, and
intended to be eternal. But you will find, though the glory and
greatness belonging to its military genius have passed away, yet
those belonging to the arts and institutions by which it adorned
and dignified life, will again arise in another state of society."
Upon again opening his eyes, he saw Italy recovering from her
desolation, towns arising with governments almost upon the model
of ancient Athens and Rome, and these different small states rivals
in arts and arms;--he saw the remains of libraries, which had been
preserved in monasteries and churches by a holy influence, which
even the Goth and Vandal respected, again opened to the people;--he
saw Rome rising from her ashes, the fragments of statues found
amidst the ruins of her palaces and imperial villas, becoming the
models for the regeneration of art;--he saw magnificent temples
raised in this city, become the metropolis of a new and Christian
world, and ornamented with the most brilliant master-pieces of the
arts of design.--"Now," the Genius said, "society has taken its
modern and permanent aspect. Consider for a moment its relations
to letters and to arms, as contrasted with those of the ancient
world." He looked, and he saw that, in the place of the rolls
of papyrus, libraries were now filled with books. "Behold," the
Genius said, "THE PRINTING PRESS! By the invention of Faust, the
productions of genius are, as it were, made imperishable, capable
of indefinite multiplication, and rendered an unalienable heritage
of the human mind. By this art, apparently so humble, the progress
of society is secured, and man is spared the humiliation of
witnessing again scenes like those which followed the destruction
of the Roman Empire. Now look to the warriors of modern times; you
see the spear, the javelin, and the cuirass are changed for the
musket and the light artillery. The German monk who discovered
gunpowder did not meanly affect the destinies of mankind; wars are
become less bloody by becoming less personal; mere brutal strength
is rendered of comparatively little avail; all the resources of
civilization are required to move a large army; wealth, ingenuity,
and perseverance become the principal elements of success;
civilized man is rendered in consequence infinitely superior to the
savage, and gunpowder gives permanence to his triumph, and secures
the cultivated nations from being ever again overrun by the inroads
of millions of barbarians."[116]
[116] This is a question which Gibbon has very eloquently
discussed ("_General Observations on the Fall of the Roman Empire
in the West_," vol. vi.) "Cannon and fortifications now form
an impregnable barrier against the Tartar horse; and Europe is
secure from any future irruption of barbarians; since, before
they can conquer, they must cease to be barbarous." What an
extraordinary illustration does this principle find in the
history of our possessions in India, where, to speak in round
numbers, thirty thousand Europeans keep no less than one hundred
million of natives in subjection!
The Genius then directs his attention to scenes in which are
displayed the triumphs of modern science; such as the steam-engine,
and the thousand resources furnished by the chemical and mechanical
arts; and she concludes by endeavouring to impress upon him the
conviction, "That the results of intellectual labour, or of
scientific genius, are permanent, and incapable of being lost.
Monarchs change their plans, governments their objects, a fleet or
an army effect their purpose and then pass away; but a piece of
steel touched by the magnet preserves its character for ever, and
secures to man the dominion of the trackless ocean. A new period
of society may send armies from the shores of the Baltic to those
of the Euxine, and the empire of the followers of Mahomet may be
broken in pieces by a Northern people, and the dominion of the
Britons in Asia may share the fate of Tamerlane or Zengis-khan; but
the steam-boat which ascends the Delaware, or the St. Lawrence,
will be continued to be used, and will carry the civilization of
an improved people into the deserts of North America, and into the
wilds of Canada. In the common history of the world, as compiled
by authors in general, almost all the great changes of nations are
confounded with changes in their dynasties, and events are usually
referred either to sovereigns, chiefs, heroes, or their armies,
which do, in fact, originate from entirely different causes, either
of an intellectual or moral nature."
Having instructed him in the history of man as an inhabitant of
the earth, the Genius proceeds to reveal to him the mysteries
of spiritual natures, in which the author evidently shows his
attachment to the belief that our intellectual essence is destined
hereafter to enjoy a higher and better state of planetary
existence,[117] drinking intellectual light from a purer source,
and approaching nearer to the Infinite and Divine mind. I shall
not attempt to follow him and his Genius to the verge of the solar
system, witnessing in his career the inhabitants of planets and
comets. We may upon this occasion truly apply to the author the
words of Lucretius--
"Processit longe flammantia moenia mundi."
"His vigorous and active mind was hurl'd
Beyond the flaming limits of the world."--CREECH.
In the former part of the dialogue, his poetical coruscations
appeared only as brilliant sparks thrown off by the rapidity of
the machinery which he worked for a useful end and for a definite
purpose; his vivid imagination may now be compared to a display
of fire-works, which dazzle and confound without enlightening the
senses, and leave the spectator in still more profound darkness.
[117] Under the article 'Sensation,' in the Philosophical
Dictionary, we find Voltaire indulging in a similar speculation.
"It may be, that in other globes the inhabitants possess
sensations of which we can form no idea. It is possible that the
number of our senses augments from globe to globe, and that an
existence with innumerable and perfect senses will be the final
attainment of all being."
His SECOND DIALOGUE, entitled "Discussions connected with the
Vision in the Colosæum," may be considered as a commentary upon
the views he had unfolded; and a more appropriate spot, perhaps,
could not have been selected for a conversation upon the progress
of civilization, than the summit of Vesuvius, from which, to adopt
the language of _Ambrosio_, "We see not only the power and activity
of man as existing at present, and of which the highest example
may be represented by the steam-boat departing from Palermo, but
we may likewise view scenes which carry us into the very bosom of
antiquity, and as it were make us live with the generations of past
ages."
The author, who assumes throughout this dialogue the name of
_Philalethes_, after having been duly rallied by his friends on the
subject of his vision, thus expresses himself:--"I will acknowledge
that the vision in the Colosæum is a fiction; but the most
important parts of it really occurred to me in sleep, particularly
that in which I seemed to leave the earth and launch into the
infinity of space, under the guidance of a tutelary genius. And
the origin and progress of civil society form likewise parts of
another dream which I had many years ago; and it was in the reverie
which happened when you quitted me in the Colosæum, that I wove all
these thoughts together, and gave them the form in which I narrated
them to you.--I do not say that they are strictly to be considered
as an accurate representation of my waking thoughts; for I am not
quite convinced that dreams are always the representations of the
state of the mind, modified by organic diseases or by associations.
There are certainly no absolutely new ideas produced in sleep; yet
I have had more than one instance, in the course of my life, of
most extraordinary combinations occurring in this state, which have
had considerable influence on my feelings, my imagination, and my
health."
_Philalethes_ now relates a fact to which his preceding observation
more immediately referred; he anticipates unbelief,--but he
declares that he mentions nothing but a simple fact.
"Almost a quarter of a century ago, I contracted that terrible form
of typhus fever known by the name of jail fever,--I may say, not
from any imprudence of my own, but whilst engaged in putting in
execution a plan for ventilating one of the great prisons of the
metropolis.[118] My illness was severe and dangerous; as long as
the fever continued, my dreams and deliriums were most painful and
oppressive; but when weakness consequent to exhaustion came on,
and when the probability of death seemed to my physicians greater
than that of life, there was an entire change in all my ideal
combinations. I remained in an apparently senseless or lethargic
state, but, in fact, my mind was peculiarly active; there was
always before me the form of a beautiful woman, with whom I was
engaged in the most interesting and intellectual conversation."
[118] See page 287, vol. i. for an account of this event.
_Ambrosio_ and _Onuphrio_ very naturally suggest that this could
have been no other than the image of some favourite maiden which
had haunted his imagination; but _Philalethes_ rejects with
indignation such an explanation of the vision. "I will not," he
exclaims, "allow you to treat me with ridicule on this point,
till you have heard the second part of my tale. Ten years after
I had recovered from the fever, and when I had almost lost the
recollection of the vision, it was recalled to my memory by a very
blooming and graceful maiden fourteen or fifteen years old, that
I accidentally met during my travels in Illyria; but I cannot say
that the impression made upon my mind by this female was very
strong. Now comes the extraordinary part of the narrative: ten
years after,--twenty years after my first illness, at a time when
I was exceedingly weak from a severe and dangerous malady, which
for many years threatened my life, and when my mind was almost in
a desponding state, being in a course of travels ordered by my
medical advisers, I again met the person who was the representative
of my visionary female; and to her kindness and care, I believe,
I owe what remains to me of existence. My despondency gradually
disappeared, and though my health still continued weak, life began
to possess charms for me which I had thought were for ever gone;
and I could not help identifying the living angel with the vision
which appeared as my guardian genius during the illness of my
youth."
The reader will probably agree with _Onuphrio_, in seeing in this
history nothing beyond the influence of an imagination excited by
disease.
The discourse now turns upon that part of the vision in the
Colosæum in which was exhibited the early state of man, after
his first creation, and which _Ambrosio_ considers as not only
incompatible with revelation, but likewise with reason and every
thing that we know respecting the history or traditions of the
early nations of antiquity.
I shall merely state the objection which _Ambrosio_ offers. I must
then refer the reader to the work itself for an account of the
discussion it provoked.
"_Ambrosio._--You consider man, in his early state, a savage like
those who now inhabit New Holland, or New Zealand, acquiring, by
the little use that they make of a feeble reason, the power of
supporting and extending life. Now, I contend that, if man had been
so created, he must inevitably have been destroyed by the elements,
or devoured by savage beasts, so infinitely his superiors in
physical force."
During the discussion, an opinion is advanced by _Ambrosio_, so
singular, that I must be allowed to quote it. "I consider," says
he, "all the miraculous parts of our religion as effected by
changes in the sensations or ideas of the human mind, and not by
physical changes in the order of nature! To Infinite Wisdom and
Power, a change in the intellectual state of the human being may
be the result of a momentary will, and the mere act of faith may
produce the change. How great the powers of imagination are, even
in ordinary life, is shown by many striking facts, and nothing
seems impossible to this imagination when acted upon by Divine
influence."
This is surely a most extraordinary line of argument for the
apologist of the Christian faith, and of the miracles by which it
is supported.
In the THIRD DIALOGUE, called the Unknown, the author and his
friends, _Ambrosio_ and _Onuphrio_, make an excursion to the
remains of the temples of Pæstum. "Were my existence to be
prolonged through ten centuries," exclaims the author, "I think I
could never forget the pleasure I received on that delicious spot."
In contemplating beautiful scenery, much of its interest depends
upon the feelings and associations of the moment; and the author
was upon this occasion evidently in that poetical frame of mind
which sheds a magic light over every landscape, and converts the
most ordinary objects into emblems of morality: in the admixture
of the olive and the cypress tree, he saw a connection, to
memorialize, as it were, how near each other are life and death,
joy and sorrow; while the music of the birds, and, above all, the
cooing of the turtle-doves, by overpowering the murmuring of the
waves and the whistling of the winds, served but to show him that,
in the strife of nature, the voice of love is predominant.
With their hearts touched by the scene they had witnessed, the
travellers descended to the ruins, and began to examine those
wonderful remains which have outlived even the name of the people
by whom they were raised. While engaged in measuring the Doric
columns in the interior of the Temple of Neptune, a stranger,
remarkable both in dress and appearance, was observed to be writing
in a memorandum book; the author immediately addresses him, and
becoming mutually pleased with each other, they enter into a
conversation of high scientific interest.
The sentiments delivered by the "UNKNOWN," for by this title is the
philosopher designated, notwithstanding their dramatic dress, are
evidently to be received as the bequest of the latest scientific
opinions of Sir H. Davy upon several important subjects, and must
consequently command our respect and consideration.
To a question relative to the nature of the masses of travertine,
of which the ruins consisted, the Unknown replied, that they
were certainly produced by deposition from water; and he rather
believed, that a lake in the immediate neighbourhood of the city
furnished the quarry. The party are then described as visiting this
spot.
"There was something peculiarly melancholy in the character of this
water; all the herbs around it were grey, as if incrusted with
marble; a few buffaloes were slaking their thirst in it, which ran
wildly away at our approach, and appeared to retire into a rocky
excavation or quarry at the end of the lake. 'There,' said the
stranger, 'is what I believe to be the source of those large and
durable stones which you see in the plain before you. This water
rapidly deposits calcareous matter, and even, if you throw a stick
into it, a few hours is sufficient to give it a coating of this
substance. Whichever way you turn your eyes, you see masses of this
recently produced marble, the consequence of the overflowing of the
lake during the winter floods.'
* * * * *
"This water is like many, I may say most, of the sources which rise
at the foot of the Apennines; it holds carbonic acid in solution,
which has dissolved a portion of the calcareous matter of the rock
through which it has passed:--this carbonic acid is dissipated
in the atmosphere, and the marble, slowly thrown down, assumes a
crystalline form, and produces coherent stones. The lake before us
is not particularly rich in the quantity of calcareous matter, for,
as I have found by experience, a pint of it does not afford more
than five or six grains; but the quantity of fluid and the length
of time are sufficient to account for the immense quantities of
tufa and rock which, in the course of ages, have accumulated in
this situation.
* * * * *
"It can, I think, be scarcely doubted that there is a source of
volcanic fire at no great distance from the surface, in the whole
of southern Italy; and, this fire acting upon the calcareous rocks
of which the Apennines are composed, must constantly detach from
them carbonic acid, which rising to the sources of the springs,
deposited from the waters of the atmosphere, must give them their
impregnation, and enable them to dissolve calcareous matter. I need
not dwell upon Ætna, Vesuvius, or the Lipari Islands, to prove that
volcanic fires are still in existence; and there can be no doubt
that, in earlier periods, almost the whole of Italy was ravaged by
them; even Rome itself, the eternal city, rests upon the craters of
extinct volcanoes; and I imagine that the traditional and fabulous
record of the destruction made by the conflagration of Phaeton, in
the chariot of the Sun, and his falling into the Po, had reference
to a great and tremendous igneous volcanic eruption which extended
over Italy, and ceased only near the Po, at the foot of the Alps.
Be this as it may, the sources of carbonic acid are numerous, not
merely in the Neapolitan but likewise in the Roman and Tuscan
states. The most magnificent waterfall in Europe, that of the
Velino near Terni, is partly fed by a stream containing calcareous
matter dissolved by carbonic acid, and it deposits marble, which
crystallizes even in the midst of its thundering descent and foam,
in the bed in which it falls.
"There is a lake in Latium, a few yards above the Lacus Albula,
where the ancient Romans erected their baths, which sends down a
considerable stream of tepid water to the larger lake; but this
water is less strongly impregnated with carbonic acid; the largest
lake is actually a saturated solution of this gas, which escapes
from it in such quantities in some parts of its surface, that it
has the appearance of being actually in ebullition. Its temperature
I ascertained to be, in the winter, in the warmest parts, above
80 degrees of Fahrenheit, and as it appears to be pretty constant,
it must be supplied with heat from a subterraneous source, being
nearly twenty degrees above the mean temperature of the atmosphere.
Kircher has detailed, in his _Mundus Subterraneus_, various wonders
respecting this lake, most of which are unfounded; such as, that
it is unfathomable,--that it has at the bottom the heat of boiling
water, and that floating islands rise from the gulf which emits it.
It must certainly be very difficult, or even impossible, to fathom
a source which rises with so much violence from a subterraneous
excavation; and at a time when chemistry had made small progress,
it was easy to mistake the disengagement of carbonic acid for an
actual ebullition. The floating islands are real; but neither the
Jesuit, nor any of the writers who have since described this lake,
had a correct idea of their origin, which is exceedingly curious.
The high temperature of this water, and the quantity of carbonic
acid that it contains, render it peculiarly fitted to afford a
pabulum or nourishment to vegetable life; the banks of travertine
are every where covered with reeds, lichens, confervæ, and various
kinds of aquatic vegetables; and at the same time that the process
of vegetable life is going on, the crystallizations of the
calcareous matter, which is every where deposited in consequence of
the escape of carbonic acid, likewise proceed, giving a constant
milkiness to what from its tint would otherwise be a blue fluid. So
rapid is the vegetation, owing to the decomposition of the carbonic
acid, that even in winter, masses of confervæ and lichens, mixed
with deposited travertine, are constantly detached by the current
of water from the bank, and float down the stream, which being a
considerable river, is never without many of these small islands
on its surface; they are sometimes only a few inches in size,
and composed merely of dark green confervæ, or purple or yellow
lichens; but they are sometimes even of some feet in diameter, and
contain seeds and various species of common water-plants, which are
usually more or less incrusted with marble. There is, I believe, no
place in the world where there is a more striking example of the
opposition or contrast of the laws of animate and inanimate nature,
of the forces of inorganic chemical affinity and those of the
powers of life. Vegetables, in such a temperature, and every where
surrounded by food, are produced with a wonderful rapidity; but
the crystallizations are formed with equal quickness, and they are
no sooner produced than they are destroyed together. The quantity
of vegetable matter and its heat make it the resort of an infinite
variety of insect tribes; and, even in the coldest days in winter,
numbers of flies may be observed on the vegetables surrounding its
banks or on its floating islands, and a quantity of their larvæ
may be seen there, sometimes incrusted and entirely destroyed by
calcareous matter, which is likewise often the fate of the insects
themselves, as well as of various species of shell-fish that are
found amongst the vegetables which grow and are destroyed in the
travertine on its banks.
* * * * *
"I have passed many hours, I may say, many days, in studying the
phenomena of this wonderful lake; it has brought many trains of
thought into my mind connected with the early changes of our globe,
and I have sometimes reasoned from the forms of plants and animals
preserved in marble in this warm source, to the grander depositions
in the secondary rocks, where the zoophytes or coral insects have
worked upon a grand scale, and where palms and vegetables now
unknown are preserved with the remains of crocodiles, turtles, and
gigantic extinct animals of the _Sauri_ genus, and which appear to
have belonged to a period when the whole globe possessed a much
higher temperature.
* * * * *
"Then, from all we know, this lake, except in some change in its
dimensions, continues nearly in the same state in which it was
described seventeen hundred years ago by Pliny, and I have no doubt
contains the same kinds of floating islands, the same plants,
and the same insects. During the fifteen years that I have known
it, it has appeared precisely identical in these respects; and
yet it has the character of an accidental phenomenon depending
upon subterraneous fire. How marvellous then are those laws by
which even the humblest types of organic existence are preserved,
though born amidst the sources of their destruction, and by which
a species of immortality is given to generations, floating, as it
were, like evanescent bubbles on a stream raised from the deepest
caverns of the earth, and instantly losing what may be called its
spirit in the atmosphere!"
From this interesting discourse on the formation of Travertine,
the conversation naturally turned to Geology; and I shall here
again be compelled to give another copious extract, in order
to show what were the latest opinions of Sir H. Davy upon this
subject. If any doubt could exist as to the views here given being
those entertained by the author, it is at once removed by his
letter to Mr. Poole, in which, alluding to the work under review,
he says, "_It contains the essence of my philosophical opinions._"
"On the geological scheme of the early history of the globe,
there are only analogies to guide us, which different minds may
apply and interpret in different ways; but I will not trifle
with a long preliminary discourse. Astronomical deductions and
actual measures by triangulation prove that the globe is an oblate
spheroid flattened at the poles; and this form, we know, by strict
mathematical demonstrations, is precisely the one which a fluid
body revolving round its axis and become solid at its surface by
the slow dissipation of its heat or other causes, would assume. I
suppose, therefore, that the globe, in the first state in which
the imagination can venture to consider it, was a fluid mass with
an immense atmosphere, revolving in space round the sun, and that
by its cooling, a portion of its atmosphere was condensed in water
which occupied a part of the surface. In this state, no forms of
life, such as now belong to our system, could have inhabited it;
and I suppose the crystalline rocks, or, as they are called by
geologists, the _primary_ rocks, which contain no vestiges of a
former order of things, were the results of the first consolidation
on its surface. Upon the farther cooling, the water which more
or less had covered it, contracted; depositions took place,
shell-fish, and coral insects of the first creation began their
labours, and islands appeared in the midst of the ocean, raised
from the deep by the productive energies of millions of zoophytes.
These islands became covered with vegetables fitted to bear a high
temperature, such as palms, and various species of plants similar
to those which now exist in the hottest part of the world. And
the submarine rocks or shores of these new formations of land
became covered with aquatic vegetables, on which various species
of shell-fish and common fishes found their nourishment. The
fluids of the globe in cooling deposited a large quantity of the
materials they held in solution, and these deposits agglutinating
together the sand, the immense masses of coral rocks, and some of
the remains of the shells and fishes found round the shores of the
primitive lands, produced the first order of _secondary_ rocks.
"As the temperature of the globe became lower, species of the
oviparous reptiles were created to inhabit it; and the turtle,
crocodile, and various gigantic animals of the _Sauri_ kind, seem
to have haunted the bays and waters of the primitive lands. But in
this state of things there was no order of events similar to the
present,--the crust of the globe was exceedingly slender, and the
source of fire a small distance from the surface. In consequence of
contraction in one part of the mass, cavities were opened, which
caused the entrance of water, and immense volcanic explosions
took place, raising one part of the surface, depressing another,
producing mountains and causing new and extensive depositions from
the primitive ocean. Changes of this kind must have been extremely
frequent in the early epochas of nature; and the only living forms
of which the remains are found in the strata that are the monuments
of these changes, are those of plants, fishes, birds, and oviparous
reptiles, which seem most fitted to exist in such a war of the
elements.
"When these revolutions became less frequent, and the globe
became still more cooled, and the inequalities of its temperature
preserved by the mountain chains, more perfect animals became
its inhabitants, many of which, such as the mammoth, megalonix,
megatherium, and gigantic hyena, are now extinct. At this period,
the temperature of the ocean seems to have been not much higher
than it is at present, and the changes produced by occasional
eruptions of it have left no consolidated rocks. Yet one of
these eruptions appears to have been of great extent and of some
duration, and seems to have been the cause of those immense
quantities of water-worn stones, gravel, and sand, which are
usually called _diluvian_ remains;--and it is probable that this
effect was connected with the elevation of a new continent in the
southern hemisphere by volcanic fire. When the system of things
became so permanent, that the tremendous revolutions depending
upon the destruction of the equilibrium between the heating and
cooling agencies were no longer to be dreaded, the creation of man
took place; and since that period there has been little alteration
in the physical circumstances of our globe. Volcanoes sometimes
occasion the rise of new islands, portions of the old continents
are constantly washed by rivers into the sea, but these changes are
too insignificant to affect the destinies of man, or the nature of
the physical circumstances of things. On the hypothesis that I have
adopted, however, it must be remembered, that the present surface
of the globe is merely a thin crust surrounding a nucleus of fluid
ignited matter; and consequently, we can hardly be considered as
actually safe from the danger of a catastrophe by fire.
* * * * *
"I beg you to consider the views I have been developing as
merely hypothetical, one of the many resting-places that may be
taken by the imagination in considering this subject. There are,
however, distinct facts in favour of the idea, that the interior
of the globe has a higher temperature than the surface; the heat
increasing in mines the deeper we penetrate, and the number of warm
sources which rise from great depths, in almost all countries,
are certainly favourable to the idea. The opinion, that volcanoes
are owing to this general and simple cause, is, I think, likewise
more agreeable to the analogies of things, than to suppose them
dependent upon partial chemical changes, such as the action of air
and water upon the combustible bases of the earths and alkalies,
though it is extremely probable that these substances may exist
beneath the surface, and may occasion some results of volcanic
fire;--and on this subject my notion may perhaps be the more
trusted, as for a long while I thought volcanic eruptions were
owing to chemical agencies of the newly discovered metals of the
earths and alkalies, and I made many and some dangerous experiments
in the hope of confirming this notion, but in vain.
* * * * *
"I have no objection to the '_refined Plutonic view_,' (of
Professor Playfair and Sir James Hall,) as capable of explaining
many existing phenomena; indeed, you must be aware that I have
myself had recourse to it. What I contend against is, its
application to explain the formations of the secondary rocks, which
I think clearly belong to an order of facts not at all embraced by
it. In the Plutonic system, there is one simple and constant order
assumed, which may be supposed eternal. The surface is constantly
imagined to be disintegrated, destroyed, degraded, and washed into
the bosom of the ocean by water, and as constantly consolidated,
elevated, and regenerated by fire; and the ruins of the old form
the foundations of the new world. It is supposed that there are
always the same types both of dead and living matter,--that the
remains of rocks, of vegetables, and animals of one age are found
imbedded in rocks raised from the bottom of the ocean in another.
Now, to support this view, not only the remains of living beings
which at present people the globe, might be expected to be found in
the oldest secondary strata, but even those of the art of man, the
most powerful and populous of its inhabitants, which is well known
not to be the case. On the contrary, each stratum of the secondary
rocks contains remains of peculiar and mostly now unknown species
of vegetables and animals. In those strata which are deepest, and
which must consequently be supposed to be the earliest deposited,
forms even of vegetable life are rare; shells and vegetable remains
are found in the next order; the bones of fishes and oviparous
reptiles exist in the following class; the remains of birds, with
those of the same genera mentioned before, in the next order; those
of quadrupeds of extinct species in a still more recent class;
and it is only in the loose and slightly consolidated strata of
gravel and sand, and which are usually called diluvian formations,
that the remains of animals, such as now people the globe, are
found, with others belonging to extinct species. But in none of
these formations, whether called secondary, tertial, or diluvial,
have the remains of man, or any of his works, been discovered. It
is, I think, impossible to consider the organic remains found in
any of the earlier secondary strata, the lias-limestone and its
congenerous formations, for instance, without being convinced,
that the beings whose organs they formed belonged to an order of
things entirely different from the present. Gigantic vegetables,
more nearly allied to the palms of the equatorial countries than
to any other plants, can only be imagined to have lived in a very
high temperature; and the immense reptiles, the _Megalosauri_, with
paddles instead of legs, and clothed in mail, in size equal, or
even superior to the whale; and the great amphibia _Plethiosauri_,
with bodies like turtles, but furnished with necks longer than
their bodies, probably to enable them to feed on vegetables growing
in the shallows of the primitive ocean, seem to show a state in
which low lands, or extensive shores, rose above an immense calm
sea, and when there were no great mountain chains to produce
inequalities of temperature, tempests, or storms. Were the surface
of the earth now to be carried down into the depths of the ocean,
or were some great revolution of the waters to cover the existing
land, and it was again to be elevated by fire, covered with
consolidated depositions of sand or mud, how entirely different
would it be in its characters from any of the secondary strata!
Its great features would undoubtedly be the works of man: hewn
stones, and statues of bronze and marble, and tools of iron, and
human remains, would be more common than those of animals, on
the greatest part of the surface; the columns of Pæstum, or of
Agrigentum, or the immense iron bridges of the Thames, would offer
a striking contrast to the bones of the crocodiles, or _Sauri_,
in the older rocks, or even to those of the mammoth, or _Elephas
primogenius_, in the diluvial strata. And whoever dwells upon this
subject must be convinced, that the present order of things, and
the comparatively recent existence of man, as the master of the
globe, is as certain as the destruction of a former and a different
order, and the extinction of a number of living forms, which have
now no types in being, and which have left their remains wonderful
monuments of the revolutions of nature."
The FOURTH DIALOGUE, to which is given the title of "The Proteus,
or Immortality," is of a more desultory nature than those which
precede it. It contains many beautiful descriptions of scenery in
the Alpine country of Austria; furnishes an interesting account
of that most singular reptile the _Proteus Anguinus_, which is
found only in the limestone caverns of Carniola, and concludes with
reflections upon the indestructibility of the sentient principle.
The author's companion, during the tour he describes, is a
scientific friend, whom he calls _Eubathes_. The dialogue opens
with a passage of considerable pathos and eloquence: the author
having been recalled to England by a melancholy event, the death of
a very near and dear relation, describes his feelings on entering
London.
"In my youth, and through the prime of manhood, I never entered
London without feelings of pleasure and hope. It was to me as
the grand theatre of intellectual activity, the field of every
species of enterprise and exertion, the metropolis of the world
of business, thought, and action. There, I was sure to find
the friends and companions of my youth, to hear the voice of
encouragement and praise. There, society of the most refined kind
offered daily its banquets to the mind, with such variety that
satiety had no place in them, and new objects of interest and
ambition were constantly exciting attention either in politics,
literature, or science.
"I now entered this great city in a very different tone of
mind--one of settled melancholy, not merely produced by the
mournful event which recalled me to my country, but owing likewise
to an entire change in the condition of my physical, moral, and
intellectual being. My health was gone, my ambition was satisfied;
I was no longer excited by the desire of distinction; what I
regarded most tenderly was in the grave; and to take a metaphor,
derived from the change produced by time in the juice of the grape,
my cup of life was no longer sparkling, sweet, and effervescent; it
had lost its sweetness without losing its power, and it had become
bitter."
There is perhaps not a more splendid passage to be found in the
work; and it is scarcely inferior to Dr. Johnson's memorable
conclusion to the preface of his Dictionary.
"After passing a few months in England," says he, "and enjoying (as
much as I could enjoy any thing) the society of the few friends
who still remained alive, the desire of travel again seized me.
I had preserved amidst the wreck of time, one feeling strong and
unbroken--the love of natural scenery; and this, in advanced life,
formed a principal motive for my plans of conduct and action."
The fall of the Traun, about ten miles below Gmünden, was one of
his favourite haunts; and he describes an accident of the most
awful description which befell him at this place. While amusing
himself on the water by a rapid species of locomotion, in a
boat so secured by a rope as to allow only of a limited range,
the tackle gave way, and he was rapidly precipitated down the
cataract. He remained for some time after his rescue in a state
of insensibility, and on recovering found himself attended by his
mysterious friend the "Unknown," who had so charmed him in his
excursion to Pæstum.
With this stranger, he proceeded on his tour; and he again becomes
the medium through which much philosophical information is conveyed
to the reader.
They visit together the grotto of the Maddalena at Adelsberg, and
he gives us the conversation that took place in that extraordinary
cavern.
"_Philalethes._--If the awful chasms of dark masses of rock
surrounding us appear like the work of demons, who might be
imagined to have risen from the centre of the earth, the beautiful
works of nature above our heads may be compared to a scenic
representation of a temple or banquet-hall for fairies or genii,
such as those fabled in the Arabian romances.
"_The Unknown._--A poet might certainly place here the palace of
the king of the Gnomes, and might find marks of his creative power
in the small lake close by, on which the flame of the torch is now
falling; for, there it is that I expect to find the extraordinary
animals which have been so long the objects of my attention.
"_Eubathes._--I see three or four creatures, like slender fish,
moving on the mud below the water.
"_The Unknown._--I see them; they are the Protei,--now I have them
in my fishing-net, and now they are safe in the pitcher of water.
At first view, you might suppose this animal to be a lizard, but it
has the motions of a fish. Its head, and the lower part of its body
and its tail, bear a strong resemblance to those of the eel; but
it has no fins; and its curious bronchial organs are not like the
gills of fishes; they form a singular vascular structure, as you
see, almost like a crest, round the throat, which may be removed
without occasioning the death of the animal, who is likewise
furnished with lungs. With this double apparatus for supplying air
to the blood, it can live either below or above the surface of
the water. Its fore-feet resemble hands, but they have only three
claws or fingers, are too feeble to be of use in grasping, or
supporting the weight of the animal; the hinder feet have only two
claws or toes, and in larger specimens are found so imperfect as to
be almost obliterated. It has small points in place of eyes, as if
to preserve the analogy of nature. Its nasal organs appear large;
and it is abundantly furnished with teeth, from which it may be
concluded that it is an animal of prey; yet in its confined state
it has never been known to eat, and it has been kept alive for many
years by occasionally changing the water in which it is placed.
"_Eubathes._--Is this the only place in Carniola where these
animals are found?
"_The Unknown._--They were first discovered here by the late Baron
Zois; but they have since been found, though rarely, at Sittich,
about thirty miles distant, thrown up by water from a subterraneous
cavity; and I have lately heard it reported that some individuals
of the same species have been recognised in the calcareous strata
in Sicily. I think it cannot be doubted, that their natural
residence is an extensive deep subterranean lake, from which in
great floods they sometimes are forced through the crevices of the
rocks into this place where they are found; and it does not appear
to me impossible, when the peculiar nature of the country in which
we are is considered, that the same great cavity may furnish the
individuals which have been found at Adelsberg and at Sittich.
* * * * *
"This adds one more instance to the number already known of the
wonderful manner in which life is produced and perpetuated in every
part of our globe, even in places which seem the least suited to
organized existence. And the same infinite power and wisdom which
has fitted the camel and the ostrich for the deserts of Africa, the
swallow that secretes its own nest for the caves of Java, the whale
for the Polar seas, and the morse and white bear for the Arctic
ice, has given the Proteus to the deep and dark subterraneous
lakes of Illyria,--an animal to whom the presence of light is not
essential, and who can live indifferently in air and in water, on
the surface of the rock, or in the depths of the mud."
Much interesting physiological discussion follows. I shall,
however, merely notice the opinion delivered by the "Unknown,"
on the subject of respiration, and which I think shows that, at
the conclusion of his career, Davy entertained the same notions,
with regard to the communication of some ethereal principle to the
blood, as he maintained in the earlier part of his life.[119]--"The
obvious chemical alteration of the air is sufficiently simple in
this process; a certain quantity of carbon only is added to it,
and it receives an addition of heat or vapour; the volumes of
elastic fluid inspired and expired (making allowance for change
of temperature,) are the same, and if ponderable agents only were
to be regarded, it would appear as if the only use of respiration
were to free the blood from a certain quantity of carbonaceous
matter. But it is probable that this is only a secondary object,
and that the change produced by respiration upon the blood is of
a much more important kind. Oxygen, in its elastic state, has
properties which are very characteristic; it gives out light by
compression, which is not certainly known to be the case with any
other elastic fluid except those which oxygen has entered without
undergoing combustion; and from the fire it produces in certain
processes, and from the manner in which it is separated by positive
electricity in the gaseous state from its combinations, it is
not easy to avoid the supposition, that it contains, besides its
ponderable elements, some very subtile matter which is capable of
assuming the form of heat and light. _My idea_ is, that the common
air inspired enters into the venous blood entire, in a state of
dissolution, carrying with it its subtile or ethereal part, which
in ordinary cases of chemical change is given off; that it expels
from the blood carbonic acid gas and azote; and that, in the course
of the circulation, its ethereal part and its ponderable part
undergo changes which belong to laws that cannot be considered
as chemical,--the ethereal part probably producing animal heat
and other effects, and the ponderable part contributing to form
carbonic acid and other products. The arterial blood is necessary
to all the functions of life, and it is no less connected with the
irritability of the muscles and the sensibility of the nerves than
with the performance of all the secretions."
[119] See vol. i. page 70.
The FIFTH DIALOGUE is entitled "The Chemist." Its object is to
demonstrate the importance of this noble science. An interlocutor
is made to disparage its utility, and to mark its weaker points.
These of course are answered, the sceptic becomes a true believer,
and the intellectual gladiators separate mutually satisfied with
each other.
"_Eubathes._--I feel disposed to join you in attacking this
favourite study of our friend, _but merely_ to provoke him to
defend it, in order to call forth his skill and awaken his
eloquence.
"_The Unknown._--I have no objection. Let there be a fair
discussion: remember, we fight only with foils, and the point of
mine shall be covered with velvet."
After having enumerated the scientific attainments necessary to
constitute the chemist, and described the apparatus essential
for understanding what has been already done in the science, he
proceeds to define the intellectual qualities which he considers
necessary for discovery, or for the advancement of the science.
Amongst them, patience, industry, and neatness in manipulation,
and accuracy and minuteness in observing and registering the
phenomena which occur, are essential. A steady hand and a quick eye
are most useful auxiliaries; but there have been very few great
chemists who have preserved these advantages through life; for
the business of the laboratory is often a service of danger, and
the elements, like the refractory spirits of romance, though the
obedient slaves of the magician, yet sometimes escape the influence
of his talisman, and endanger his person. Both the hands and eyes
of others, however, may be sometimes advantageously made use of. By
often repeating a process or an observation, the errors connected
with hasty operations or imperfect views are annihilated; and,
provided the assistant has no preconceived notions of his own,
and is ignorant of the object of his employer in making the
experiment, his simple and bare detail of facts will often be
the best foundation for an opinion. With respect to the higher
qualities of intellect necessary for understanding and developing
the general laws of the science, the same talents, I believe, are
required as for making advancement in every other department of
human knowledge; I need not be very minute. The imagination must
be active and brilliant in seeking analogies; yet entirely under
the influence of the judgment in applying them. The memory must be
extensive and profound; rather, however, calling up general views
of things than minute trains of thought;--the mind must not be like
an Encyclopedia,--a burthen of knowledge, but rather a critical
Dictionary, which abounds in generalities, and points out where
more minute information may be obtained.
* * * * *
"In announcing even the greatest and most important discoveries,
the true philosopher will communicate his details with modesty and
reserve; he will rather be a useful servant of the public, bringing
forth a light from under his cloak when it is needed in darkness,
than a charlatan exhibiting fire-works, and having a trumpeter to
announce their magnificence.
"I see you are smiling, and think what I am saying in bad taste;
yet, notwithstanding, I will provoke your smiles still farther,
by saying a word or two on his other moral qualities. That he
should be humble-minded, you will readily allow, and a diligent
searcher after truth, and neither diverted from this great object
by the love of transient glory or temporary popularity, looking
rather to the opinion of ages than to that of a day, and seeking
to be remembered and named rather in the epochas of historians
than in the columns of newspaper writers or journalists. He should
resemble the modern geometricians in the greatness of his views
and the profoundness of his researches, and the ancient alchemists
in industry and piety. I do not mean that he should affix written
prayers and inscriptions[120] of recommendations of his processes
to Providence, as was the custom of Peter Wolfe, who was alive in
my early days; but his mind should always be awake to devotional
feelings; and in contemplating the variety and the beauty of the
external world, and developing its scientific wonders, he will
always refer to that Infinite Wisdom, through whose beneficence he
is permitted to enjoy knowledge; and, in becoming wiser, he will
become better,--he will rise at once in the scale of intellectual
and moral existence, his increased sagacity will be subservient to
a more exalted faith, and in proportion as the veil becomes thinner
through which he sees the causes of things, he will admire more the
brightness of the divine light by which they are rendered visible."
[120] In illustration of the pious custom here alluded to by Sir
H. Davy, it may be observed, that the vessels of the alchemists
very commonly bore some emblem; such, for instance, as that of
the cross; and from which, indeed, the word _crucible_ derived
its appellation.
The SIXTH AND LAST DIALOGUE, entitled "POLA, or TIME," presents a
series of reflections, to which a view of the decaying amphitheatre
at Pola, an ancient town in the peninsula of Istria, is represented
as having given origin. On former occasions, the inspection of the
mouldering works of past ages called up trains of thought rather of
a moral than of a physical character; in the present dialogue, the
effects of time are considered in their relations to the mechanical
and chemical laws by which material forms are destroyed, or rather
changed,--for the author has shown by a number of beautiful
examples, that without decay there can be no reproduction, and that
the principle of change is a principle of life.
Having considered the influence of gravitation, the chemical
and mechanical agencies of water, air, and electricity, and the
energies of organized beings, in producing those diversified
phenomena which, in our metaphysical abstractions, we universally
refer to Time, he proceeds to enquire how far art can counteract
their operation. A great philosopher, he observes, has said, "Man
can in no other way command Nature but in obeying her laws:" it is
evident that, by the application of some of those principles which
she herself employs, we may for a while arrest the progress of
changes which are ultimately inevitable.
"Yet, when all is done that can be done in the work of
conservation, it is only producing a difference in the degree of
duration. It is evident that none of the works of a mortal can be
eternal, as none of the combinations of a limited intellect can
be infinite. The operations of Nature, when slow, are no less
sure; however man may, for a time, usurp dominion over her, she
is certain of recovering her empire. He converts her rocks, her
stones, her trees, into forms of palaces, houses, and ships; he
employs the metals found in the bosom of the earth, as instruments
of power, and the sands and clays which constitute its surface,
as ornaments and resources of luxury; he imprisons air by water,
and tortures water by fire to change, or modify, or destroy the
natural forms of things. But in some lustrums his works begin to
change, and in a few centuries they decay and are in ruins; and his
mighty temples, framed as it were for immortal and divine purposes,
and his bridges formed of granite and ribbed with iron, and his
walls for defence, and the splendid monuments by which he has
endeavoured to give eternity even to his perishable remains, are
gradually destroyed; and these structures, which have resisted the
waves of the ocean, the tempests of the sky, and the stroke of the
lightning, shall yield to the operation of the dews of heaven,--of
frost, rain, vapour, and imperceptible atmospheric influences;
and as the worm devours the lineaments of his mortal beauty, so
the lichens and the moss and the most insignificant plants shall
feed upon his columns and his pyramids, and the most humble and
insignificant insect shall undermine and sap the foundations of his
colossal works, and make their habitations amongst the ruins of his
palaces and the falling seats of his earthly glory."
On no occasion can such a subject be presented to a contemplative
mind, without filling it with awe and wonder; but the circumstances
under which these reflections are presented to us, in the
last days of our philosopher, impress upon them an almost
oracular solemnity. When we remember that while the mind of the
philosopher was thus engaged in identifying the processes of
decay with those of renovation in the system of nature, his body
was palsied, and the current of his life fast ebbing, we cannot
but admire that active intelligence which sparkled with such
undiminished lustre amidst the wreck of its earthly tenement.
In the extracts which have been introduced from this last work,
I trust the pledge that was given in the earlier part of these
memoirs, has been redeemed by showing that a powerful imagination
is not necessarily incompatible with a sound judgment, that the
flowers of fancy are not always blighted by the cold realities of
science, but that the poet and philosopher may, under the auspices
of a happy genius, mutually assist each other in expounding the
mysteries of nature. It cannot be denied, as a general aphorism,
that the tree which expands its force in flowers is generally
deficient in fruit; but the mind of Davy, to borrow one of his own
metaphors, may be likened to those fabled of the Hesperides, which
produced at once buds, leaves, blossoms, and fruits.
The happy effects resulting from this rare and nicely adjusted
combination of talents, offer themselves as interesting subjects
of biographical contemplation, and they can be studied only with
success by a comparative analysis of different minds.
That the superiority of Davy greatly depended upon the vivacity
and compass of his imagination cannot be doubted, and such an
opinion was well expressed by Mr. Davies Gilbert, in his late
address to the Society:--"The poetic bent of Davy's mind seems
never to have left him. To that circumstance I would ascribe the
distinguishing features in his character and in his discoveries:--a
vivid imagination sketching out new tracks in regions unexplored,
for the judgment to select those leading to the recesses of
abstract truth."
I have always thought that the mind of the late Dr. Clarke, the
Mineralogical Professor of Cambridge, was little less imaginative
than that of Davy; but it was deficient in judgment, and therefore
often conducted him to error instead of to truth. Dr. Black was not
deficient in imagination, and certainly not in judgment; but there
was a constitutional apathy, arising probably from ill health,
which damped his noblest efforts.[121]
[121] In addition to the anecdote already related of him, the
following may serve to give a still greater force to this
opinion. Soon after the appearance of Mr. Cavendish's paper on
hydrogen gas, in which he made an approximation to the specific
gravity of that body, showing that it was at least ten times
lighter than common air, Dr. Black invited a party of his
friends to supper, informing them that he had a curiosity to
show them. Dr. Hutton and several others assembled, when, having
the allentois of a calf filled with hydrogen gas, upon setting
it at liberty, it immediately ascended, and adhered to the
ceiling. The phenomenon was easily accounted for: it was taken
for granted that a small black thread had been attached to the
allentois,--that this thread passed through the ceiling, and that
some one in the apartment above, by pulling the thread, elevated
it to the ceiling, and kept it in that position. This explanation
was so probable, that it was acceded to by the whole company;
though, like many other plausible theories, it was not true;
for when the allentois was brought down, no thread whatever was
found attached to it. Dr. Black explained the cause of the ascent
to his admiring friends; but such was his unaccountable apathy,
that he never gave the least account of this curious experiment
even to his class; and more than twelve years elapsed before this
obvious property of hydrogen gas was applied to the elevation of
air balloons, by M. Charles, in Paris.
I am indebted for this anecdote to the "History of Chemistry," a
very able work by Dr. Thomson, constituting the third number of
the National Library.
It is by the rarity with which the talent of seizing upon remote
analogies is associated with a spirit of patient and subtile
investigation of details, and a quick perception of their value,
that the fact so truly stated by Mr. Babbage is to be explained;
_viz._ that long intervals frequently elapse between the discovery
of new principles in science and their practical application: thus
he observes, that "the principle of the hydrostatic paradox was
known as a speculative truth in the time of Stevinus, as far back
as the year 1600,--and its application to raising heavy weights has
long been stated in elementary treatises on natural philosophy,
as well as constantly exhibited in lectures; yet it may fairly be
regarded as a mere abstract principle, until the late Mr. Bramah,
by substituting a pump, instead of the smaller column, converted
it into a most valuable and powerful engine. The principle of the
convertibility of the centres of oscillation and suspension in the
pendulum, discovered by Huygens more than a century and a half
ago, remained, until within these few years, a sterile though most
elegant proposition; when, after being hinted at by Prony, and
distinctly pointed out by Bonenberger, it was employed by Captain
Kater as the foundation of a most convenient method of determining
the length of the pendulum. The interval which separated the
discovery of Dr. Black, of latent heat, from the beautiful and
successful application of it to the steam-engine, was comparatively
short; but it required the efforts of two minds; and both were of
the highest order."[122]
[122] "Reflections on the Decline of Science in England," page 15.
The discoveries of Davy present themselves in striking contrast
with such instances. The same powerful genius that developed the
laws of electro-chemical decomposition, was the first to apply them
for the purpose of obviating metallic corrosion; and the nature of
_fire-damp_, and the fact of its combustion being arrested in its
passage through capillary tubes, were alike the discoveries of him
who first applied them for the construction of a safety-lamp.[123]
[123] While upon this subject, it is impossible not to notice the
discoveries of Dr. Franklin, who combined in a remarkable degree
a fertile imagination with a solid judgment; and the fruit of
this union is to be seen in the invention of conductors for the
security of ships and buildings against the effects of lightning.
The philosopher who, predicating the identity of lightning and
electricity, conceived the bold and grand idea of drawing it
down from the thunder-cloud, an experiment which in another age
would have consigned him to the dungeon for impiety, or to the
stake for witchcraft, himself applied this wonderful discovery to
the preservation of buildings, by the invention of pointed rods
of iron. Of this invention it may be truly said, that he beat
Nature with her own weapons, and triumphed over her power by an
obedience to her own laws.
In contrasting the genius of Wollaston with that of Davy, let me
not be supposed to invite a comparison to the disparagement of
either, but rather to the glory of both, for by mutual reflection
each will glow the brighter. If the animating principle of
Davy's mind was a powerful imagination, generalizing phenomena,
and casting them into new combinations, so may the striking
characteristic of Wollaston's genius be said to have been an almost
superhuman perception of minute detail. Davy was ever imagining
something greater than he knew; Wollaston always knew something
more than he acknowledged:--in Wollaston, the predominant principle
was to avoid error; in Davy, it was the desire to discover truth.
The tendency of Davy, on all occasions, was to raise probabilities
into facts; while Wollaston as continually made them subservient to
the expression of doubt.
Wollaston was deficient in imagination, and under no circumstances
could he have become a Poet; nor was it to be expected that his
investigations should have led him to any of those comprehensive
generalizations which create new systems of philosophy. He well
knew the compass of his powers, and he pursued the only method by
which they could be rendered available in advancing knowledge.
He was a giant in strength, but it was the strength of Antæus,
mighty only on the earth. The extreme caution and reserve of his
manner were inseparably connected with the habits of his mind; they
pervaded every part of his character; in his amusements and in his
scientific experiments, he displayed the same nice and punctilious
observation,--whether he was angling for trout,[124] or testing for
elements,
[124] Sir Humphry Davy has told us an anecdote which well
illustrates this observation, while it affords a gratifying
testimony of the kind feeling he entertained towards a kindred
philosopher.--"There was--alas! that I must say _there was!_--an
illustrious philosopher, who was nearly of the age of fifty
before he made angling a pursuit, yet he became a distinguished
fly-fisher, and the amusement occupied many of his leisure hours,
during the last twelve years of his life. He indeed applied his
preeminent acuteness, his science, and his philosophy, to aid the
resources and exalt the pleasures of this amusement. I remember
to have seen Dr. Wollaston, a few days after he had become
a fly-fisher, carrying at his button-hole a piece of Indian
rubber, when by passing his silkworm link through a fissure in
the middle, he rendered it straight, and fit for immediate use.
Many other anglers will remember other ingenious devices of my
admirable and ever-to-be-lamented friend."--_Salmonia. Additional
Note_, Edit. 2. he alike relied for success upon his subtile
discrimination of minute circumstances.