A WORLD OF WONDERS (1845) Albany Poyntz
CHAPTER XIV
PERPETUAL LAMPS AND ARCHIMEDES
(Investigator Magazine 219, 2024 November)
Stability is not the characteristic of man or his works. The discovery
of perpetual motion has long been the object of our ambition; the sole
approach to which appears to be our futile perseverance in the pursuit.
Let us be content, therefore, with aspiring to duration, a sufficient
triumph for perishable man; and be it noted that this quality, though
impressed by human art upon inert matter, such as the Pyramids of
Egypt, is incompatible with the mutability of our social institutions.
The word perpetual has been too often and too easily applied. The
marvellous is too often substituted for the true, just as great vices
are more widely apparent than great virtues. Who has not heard, for
instance, of perpetual lamps, miraculous as the Wonderful Lamp of the
Arabian Tales!
The Pagan priesthood originated these fabulous sepulchral lights; and
those of our own faith who had the weakness to adopt their deception,
endangered our confidence by recourse to unworthy trickeries. Pausanias
mentions a lamp of massive gold, consecrated by Callimachus, and
endowed with such properties as to endure a year without deterioration.
Another is said to have existed in a temple in England. Pope Gelasius
affirms, in the acts of St. Sylvester, that in the Baptistery of Rome,
there was a lamp which had burned without intermission since the reign
of Constantine, viz., half a century. That the dark ages should have
admitted such marvels is not surprising. But one of the illuminati of
the sixteenth century, Fortunio Liceti, composed a treaty concerning
the existence of such lamps, asserting that, upon opening the tomb of
the giant Pallas, a lamp was found which had been burning since the
times of the pious Æneas. Another was stated to have been found
in the tomb of Tullia, during the Pontificate of Paulinus, about
fifteen centuries and a half after its construction. In the reign of
Justinian, a portrait of our Saviour was discovered at Edessa with a
lamp unrenovated from the period of the Christian era, that is, during
a period of five centuries. Fortunio cites a vast number of similar
examples; from which he infers that the Romans possessed the secret of
making inextinguishable lamps. His conviction upon the subject is such,
that he attempts to explain the possibility by a theory that the
combustion of the smoke produced fresh oil for the nourishment of the
lamp. This must surely have been the far-famed oil of the Phœnix.
It is scarcely worth while to controvert such absurdities; the fable of
perpetual lamps having faded before the dawning light of reason. Is it,
however, to be credited, that the genius of Descartes did not secure
him against this vulgar error? The views of that great man on the
subject deserve to be quoted as a proof of the aberrations to which
superior minds are subject. "After
considering the fire produced by gunpowder," says Descartes, "which is
the most transitory in existence, let us inquire whether there can
exist a flame, enduring without the aid of fresh matter for its
support, like those found in the tombs of the ancients shut up for
centuries. I will not vouch for the truth of their existence; but think
it possible that in a vault so close that the air could never be
disturbed, the parts of the oil transformed into smoke, and from smoke
into soot, might, by sub-formation, arch themselves over the flame so
as to protect it from the air, and render it so weak as to lose the
power of consuming either oil or wick, so long as there should remain a
shred unburnt by which means the primary element existent in the flame
and identified with the little self-formed vault, might revolve therein
like a little star. It necessarily follows that the second element
became expelled on all sides, while trying to penetrate the pores still
remaining in the little dome; and the flame which remained feeble while
the place was closed, brightened the moment it was opened, and the
external air admitted. The surrounding smoke dispersed, the flame
recovers its vigour for a moment, and then expires. Such lamps, in
fact, become perpetual, only from having exhausted their oil."
This statement is extracted from the Fourth Book of the Principles of
Philosophy of Descartes. In spite of the respect due to his name, we
see in it only a tissue of verbosity exhibiting science at a nonplus,
and advocating a groundless theory. But such a chimera on the part of
so eminent a man, ought to afford consolation to second-rate
capacities, as a proof that no one is exempt from delusions.
From Descartes, let us turn to Archimedes, who conferred ten-fold power
upon the arm of man by arming it with the lever; and with becoming
deference avow our want of faith in the mirror by the burning
reflections of which he managed to destroy the Roman galleys!
"Combustible bodies," observes Descartes, "cannot be ignited by means
of mirrors unless comprehended in the necessary focus. Geometry shows
us that the distance of a focus of a concave mirror is equal to the
half of its sphere; that is, if the mirror have been set from a sphere
of a radius of one foot, the distance of the focus will be of six
inches. A sphere having a radius of one foot, gives, therefore, but a
focus of six inches, so that to establish a focus at two hundred feet,
would require a sphere with a radius of four hundred feet, or eight
hundred in diameter! Besides, how could Archimedes procure such a
mirror, when the art of casting mirrors was unknown, and the
manufacture of glass in its infancy? That it was a metallic mirror is
difficult to conceive. Such were the solutions attempted of an
insoluble problem. Doubtful anecdotes are so often and so boldly
adopted by the authors of antiquity, that we may regard as
unsubstantiated all facts upon which they are silent. Neither Livy,
Diodorus, nor Polybius mention the mirror of Archimedes; so that the
invention is probably modern, and most likely a fable of the sixteenth
century, prolific in inventions and amplifications. The press, then in
its infancy, delighted in the propagation of marvels and fallacies
attributed by their imbecile authors to the ancients, so as to assign
them some semblance of truth. Among such inventions was the mirror of
Archimedes.
Gallienus, indeed, mentions the burning of the fleet by Archimedes; but
is mute on the subject of the mirror, which he could scarcely have
omitted, had the fact been genuine. Tzetzes and Zoronas are the first
who mention it; the former in the following words:
"When the Roman galleys were within arrow-shot, Archimedes caused an
hexagonal mirror to be made, and other smaller ones, each having
twenty-four angles, which were placed at a proportionate distance, and
could be worked by their hinges and certain metallic blades; their
position being such that the rays of the sun reflected upon their
surface, produced a fire which destroyed the Roman galleys, though at
the distance of a bow-shot."
The author does not condescend to give his authority; relying for the
evidence of his authenticity upon his confederate, Zoronas, who relates
that, at the Siege of Constantinople, under the reign of Anastasius,
Probus burnt the enemy’s fleet by means of brazen mirrors. He states
that the invention was not new, but belonged to Archimedes, who, as
testified by Dion, used them at the Siege of Syracuse by Marcellus.
The mutual confederacy of a couple of mountebanks is as easily
understood as it would be susceptible of annihilation; did not such men
as Kirchen and Buffon become sureties, not for what Archimedes has
done, but for what he was capable of effecting. Previous to Descartes,
the former had asserted the possibility of igniting combustible matter
at a great distance by means of small plane mirrors, which could be
managed so that the rays might be directed upon any given object. This
was simply a theory; but Buffon decided upon making the experiment, the
result of which is well known. He caused to be constructed one hundred
and sixty-eight little mirrors six inches by eight, and directing their
rays towards a point, succeeded in igniting a body at a considerable
distance. By this he discovered a new principle, viz: that the action
of the solar rays reflected is in direct ratio of the diameter of the
focus; proving, moreover, that by multiplying the mirrors, an
indefinite line of combustion might be established.
Can we infer, however, from these experiments of Buffon, that
Archimedes actually destroyed the Roman galleys? We think not;
considering the silence of the Roman writers on the subject, and the
progress of science in the time of Buffon, with reference to its
discoveries in the time of the Siege of Syracuse by Marcellus. Whether
this mirror existed or not, however, Archimedes must be admitted to be
one of the greatest geniuses the World of Science ever produced.
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