hours; hence in that period day and night occur to every part of the
Earth, except within the Arctic circle. The light of the Sun gradually
diminishing from S, to the Arctic circle 1 2 3, where it becomes
twilight, does so according to the well-known law of radiation, equally
in all directions--hence, the circle 4 5 6 represents the whole extent
of the Sun’s light at any given time. The arc 4 E is the advancing or
morning twilight, and 6 E the receding or evening twilight; to every
place underneath a line drawn across the circle through S to N it is
noonday. It will now be easily understood that as the Sun S moves in
the direction of the arrows or from right to left, and completes the
circle A A A in 24 hours, it will produce in that period morning,
noon, evening, and night to all parts of the Earth in succession. On
referring to the diagram, it will be seen that to England, E, the
length of the day at this time of the year is the _shortest_, the
amount of light being represented by the arc E E E; and also that
the northern centre N remains in darkness during the whole daily
revolution of the Sun, the light of which terminates at the Arctic
circle 1 2 3. Thus, morning, noon, evening, midnight, the _shortest_
days, or the Winter season, and the constant or six months’ darkness
at the pole are all a part of one general phenomenon. As the Sun’s
path begins now to diminish every day until in six months, or on the
15th of June, it describes the circle B B B, it is evident that the
same extent of sunlight will reach over or beyond the pole N, as shown
in the following diagram (Fig. 28), when morning, noon, evening, and
night will again occur as before; but the amount of light passing over
England, represented by the arc E E E, is now much larger than when
the Sun was upon the circle A A A, and represents the _longest_ days,
or the _Summer_ season, and the constant, or six months’ light at the
pole. Thus, day and night, long and short days, Winter and Summer, the
long periods of alternate light and darkness at the pole, arise simply
from the Sun’s position in relation to the north pole.
[Illustration: FIG. 28.]
If the Earth is a globe, it is evident that Winter and Summer, and
long and short days, will be of the same character and duration in
corresponding latitudes, in the southern as in the northern hemisphere.
But we find that in many respects there is a marked difference; for
instance, in New Zealand, where the latitude is about the same as in
England, a remarkable difference exists in the length of day and night.
In the Cook’s Strait Almanack, for 1848, it is stated, “At Wellington,
New Zealand, December 21, Sun rises 4h. 31m., and sets at 7h. 29m., the
day being 14 hours 58 minutes. June 21st, Sun rises at 7h. 29m., and
sets at 4h. 31m., the day being 9 hours and 2 minutes. In England the
longest day is 16h. 34m., and the shortest day is 7h. 45m. Thus the
_longest day_ in New Zealand is 1 hour and 36 minutes _shorter_ than
the _longest day_ in England; and the _shortest day_ in New Zealand is
1 hour and 17 minutes _longer_ than the shortest day in England.”
In a recently published pamphlet, by W. Swainson, Esq., Attorney
General, the following passage occurs:--“Compared with an English
summer, that of Auckland is but little warmer, though much longer; but
the nights in New Zealand are always cool and refreshing.... The days
are _one hour shorter_ in the summer, and _one hour longer_ in the
winter than in England! of _twilight_ there is _little_ or _none_.”
From a work, also recently published, on New Zealand, by Arthur S.
Thompson, M.D., the following sentences are quoted:--“The summer
mornings, even in the warmest parts of the colony are sufficiently
fresh to exhilarate without chilling; and the seasons glide
imperceptibly into each other. The days are _an hour shorter_ at
_each end_ of the day in summer, and an hour longer in winter than in
England.”
A letter from a correspondent in New Zealand, dated Nelson, September
15, 1857, contains the subjoined passages:--“Even in summer people
here have no notion of going without fires in the evening; but then,
though the days are very warm and sunny, the nights are always cold.
For seven months last summer we had not one day that the Sun did
not shine as brilliantly as it does in England in the finest day in
June; and though it has more power here, the heat is not nearly so
oppressive.... But then there is not the twilight which you get in
England. Here it is light till about eight o’clock; then, in a few
minutes, it becomes too dark to see anything, and the change comes
over in almost no time.” “Twilight lasts but a short time in so low
a latitude as 28 degrees, and no sooner does the Sun peep above the
horizon, than all the gorgeous parade by which he is preceded is shaken
off, and he comes in upon us in the most abrupt and unceremonious way
imaginable.”[9] These various peculiarities could not exist in the
southern region if the Earth were spherical and moved upon axes, and
in an orbit round the Sun. If the Sun is fixed, and the Earth revolves
underneath it, the same phenomena should exist at the same distance on
each side of the Equator. But such is not the case! What can operate
to cause the twilight in New Zealand to be so much more sudden than it
is in England? The southern “hemisphere” cannot revolve more rapidly
than the northern! The distance round _a globe_ would be the same at
50° south as at 50° north, and as the whole globe would revolve once in
24 hours, the surface at the two places would move underneath the Sun
with the same velocity, and the light would approach in the morning
and recede in the evening in exactly the same manner; yet the _very
contrary_ is the fact! The twilight in England in summer is slow and
gradual, but in New Zealand it is rapid and abrupt; a difference which
is altogether incompatible with the doctrine of the Earth’s rotundity.
But, the Earth a plane, and it is a simple “matter of course.” Let E,
in Figure 28, represent England, and W New Zealand; the radius N E and
the consequent circle round N is much less than the radius N W and
its consequent circle round the same point. But as the larger circle,
radius N W is passed over by the sunlight in the same time (24 hours)
as the smaller circle, radius N E, the velocity is proportionately
greater. The velocity is the space passed over multiplied by the time
in passing, and as the space over New Zealand is much greater than the
space over England, the velocity of the Sun-light must be much greater,
and its morning and evening twilight necessarily more “abrupt and
unceremonious;” and _therefore_, it might be said with strictly logical
accuracy, the Earth is a Plane, and cannot possibly be a Globe!
[9] Captain Basil Hall, R.N., F.R.S.
SECTION 7.
CAUSE OF “SUNRISE” AND “SUNSET.”
[Illustration: FIG. 29.]
Although the Sun is at all times above and parallel to the Earth’s
surface, he appears to ascend the firmament from morning until noon,
and to descend and sink below the horizon at evening. This arises from
a simple and everywhere visible law of perspective. A flock of birds,
when passing over a flat or marshy country, always appears to descend
as it recedes; and if the flock is extensive, the first bird appears
lower, or nearer to the horizon than the last. When a balloon sails
from an observer without increasing or decreasing its altitude, it
appears gradually to approach the horizon. The farthest light in a row
of lamps appears the lowest, although each one has the same altitude.
Bearing these phenomena in mind, it will easily be seen how the Sun,
although always parallel to the surface of the Earth, must appear to
ascend when approaching, and descend after leaving the meridian or
noon-day position. Let the line A B, Fig. 29, represent a portion
of the Earth’s surface; C D of the Sun’s path, and H H, the line of
sight. The surface of the Earth, A B, will appear to ascend from B to
H, forming the horizon. When the Sun is traversing the line C D, in the
direction of the arrows, he will appear to emerge from the horizon H,
and to gradually ascend the line H D. When in the position 1, he will
_appear_ to be at the point 2; and when at 3, the apparent position
will be at 4; but when he arrives upon the meridian D, his apparent
and actual, or noon-day position, will be the same. But now, from the
point D, the Sun will appear to descend, as in Fig. 30, and when he
has passed from D to 1, he will appear at 2, and when really at 3 will
appear at 4; and thus continuing his course in the direction D C, he
will reach the horizon at H, and disappear or “set” to the observer
at H A. Thus “Sunrise” and “Sunset” are phenomena dependent entirely
upon the fact that horizontal lines parallel to each other appear to
approach or converge in the distance, the surface of the Earth being
horizontal, and the line-of-sight of the observer and the Sun’s path
being parallel with it, necessarily produce the observed phenomena.
[Illustration: FIG. 30.]
SECTION 8.
CAUSE OF SUN APPEARING LARGER WHEN RISING AND SETTING THAN WHEN ON THE
MERIDIAN.
It is well known that when a light of any kind shines through a
dense medium it will appear larger than when seen through a lighter
medium. This will be more remarkable when the medium holds aqueous
particles in solution,--as in a damp or foggy atmosphere the light of
a gas-lamp will seem greater at a given distance than it will under
ordinary circumstances. In the diagram, Figure 30, it is evident that
H D is less than H 1, H 3, or H 5. The latter (H 5) represents the
greater amount of atmosphere which the Sun has to shine through when
approaching the horizon; and as the air near the Earth is both more
dense and more damp, or holds more watery particles in solution, the
light of the Sun must be dilated or enlarged as well as modified in
colour. But the enlarged appearance of the Sun when rising and setting
is only an optical impression, as proved by actual measurement. “If
the angle of the Sun or Moon be taken either with a tube or micrometer
when they appear so large to the eye in the horizon, the measure is
identical when they are in the meridian and appear to the eye and
mind but half the size. The apparent distance of the horizon is three
or four times greater than the zenith. Hence the mental mistake of
horizontal size, for the angular dimensions are equal; the first 5° is
apparently to the eye equal to 10° or 15° at 50° or 60° of elevation;
and the first 15° fill a space to the eye equal to a third of the
quadrant. This is evidently owing to the ‘habit of sight,’ for with an
accurate instrument the measure of 5° near the horizon is equal to 5°
in the zenith.”[10]
[10] “Million of Facts,” by Sir Richard Philips, p. 537.
SECTION 9.
CAUSE OF SOLAR AND LUNAR ECLIPSES.
An Eclipse of the Sun is caused simply by the Moon passing before it,
or between it and the observer on the Earth. Of this no question has
been raised. But that an Eclipse of the Moon arises from a shadow
of the Earth is in every respect unsatisfactory. The Earth has been
proved to have no motion, either upon axes or in an orbit round the
Sun, and therefore it could never come between the Sun and the Moon.
The Earth is proved to be a Plane, always underneath the Sun and Moon,
and therefore to speak of its intercepting the light of the Sun and
thus casting its own shadow upon the Moon, is to say that which is
impossible. Besides this, cases are on record of the Sun and Eclipsed
Moon being above the horizon together. “The full Moon has sometimes
been seen above the horizon before the Sun was set. A remarkable
instance of this kind was observed at Paris on the 19th of July, 1750,
when the Moon appeared visibly Eclipsed while the Sun was distinctly
to be seen above the horizon.”[11] “On the 20th of April, 1837, the
Moon appeared to rise Eclipsed before the Sun had set. The same
phenomenon was observed on the 20th of September, 1717.”[12] “In the
lunar Eclipses of July 17, 1590; Nov. 3, 1648; June 16, 1666; and May
26, 1668, the Moon rose Eclipsed whilst the Sun was still apparently
above the horizon. Those _horizontal_ Eclipses were noticed as early
as the time of Pliny.”[13] The Moon’s entire surface, or that portion
presented to the Earth has also been distinctly seen during the whole
time of a total Eclipse, a phenomenon utterly incompatible with the
doctrine that the Earth’s shadow is the cause of it. “The Moon has
sometimes shown during a total Eclispe with an almost unaccountable
distinctness. On Dec. 22, 1703, the Moon, when totally immersed in
the Earth’s shadow, was visible at Avignon by a ruddy light of such
brilliancy that one might have imagined her body to be transparent, and
to be enlightened from behind; and on March 19th, 1848, it is stated
that so bright was the Moon’s surface during its total immersion, that
many persons could not be persuaded that it was eclipsed. Mr. Forster,
of Bruges, states, in an account of that eclipse, that the light and
dark places on the moon’s surface could be almost as well made out as
in an ordinary dull moonlight night.
[11] “Astronomy and Astronomical Instruments,” p. 105, by Geo. G.
Carey.
[12] “McCulloch’s Geography,” p. 85.
[13] “Illustrated London Almanack for 1864,” the astronomical part in
which is by James Glaisher, Esq., of the Greenwich Observatory.
“Sometimes, in a total lunar eclipse, the moon will appear quite
obscure in some parts of its surface, and in other parts will exhibit
a high degree of illumination. * * * To a certain extent I witnessed
some of these phenomena during the merely partial eclipse of February
7th, 1860. * * * I prepared, during the afternoon of February 6th for
witnessing the eclipse, without any distinct expectation of seeing much
worthy of note. I knew, however, that upwards of eight-tenths of the
disc would be covered, and I was anxious to observe with what degree
of distinctness the eclipsed portion could be viewed, partly as an
interesting fact, and partly with a view of verifying or discovering
the weak points of an engraving (in which I am concerned) of a lunar
eclipse.
“After seeing the increasing darkness of the penumbra softly merging
into the true shadow at the commencement of the eclipse (about 1
o’clock a.m., Greenwich time) I proceeded with pencil and paper,
dimly lighted by a distant lamp, to note by name the different lunar
mountains and plains (the so-called seas) over which the shadow
passed. * * * During the first hour and ten minutes I had seen nothing
unexpected. * * * I had repeatedly written down my observations of
the remarkable clearness with which the moon’s eclipsed outline could
be seen, both with the naked eye, and with the telescope; at 1 hour
58 minutes, however, I suddenly noted the ruddy colour of a _portion_
of the moon. I may as well give my notes in the original words, as
copied next day in a more connected form:--1h. 58m., Greenwich time. I
am suddenly struck by the fact that the whole of the western seas of
the moon are showing through the shadow with singular sharpness, and
that the whole region where they lie has assumed a decidedly reddish
tinge, attaining its greatest brightness at a sort of temporary polar
region, having ‘Endymion’ about the position of its imaginary pole. I
particularly notice that the ‘Lake of Sleep’ has disappeared in this
brightness, instead of standing out in a darker shade: and I notice
that this so-called polar region is not parallel with the rim of the
shadow, but rather west of it.--2h. 15m. Some clouds, though very thin
and transparent, now intervene.--2h. 20m. The sky is now cleared, How
extraordinary is the appearance of the Moon _Reddish_ is not the word
to express it; it is red--red hot! I endeavour to think of various
red objects with which to compare it, and nothing seems so like as a
_red-hot penny_--a red-hot penny with a little _white_-hot piece at its
lower edge, standing out against a dark-blue back ground; only it is
evidently not a mere disc, but beautifully rounded by shading.
“Such is its appearance with the naked eye: with the telescope its
surface varies more in tint than with the naked eye, and is not of
quite so bright a red as when thus viewed. The redness continues to be
most perceptible at a distance from the shadow’s southern edge, and to
be greatest about the region of ‘Endymion.’ The Hercynian mountains
(north of Grimaldus) are, however, of rather a bright red, and
Grimaldus shows well. Mare Crisium and the western seas are wonderfully
distinct. Not a trace to be seen of Aristarchus or Plato.--2h. 27m.
It is now nearly the middle of the eclipse. The red colour is very
brilliant to the naked eye. * * * After this, I noticed a progressive
change of tint in the Moon.--2h. 50m. The Moon does not seem to the
naked eye of so bright a red as before; and again I am reminded by its
tint of red-hot copper, or rather copper which has begun to cool. The
whole of Grimaldi is now uncovered. Through the telescope I notice a
decided grey shade at the lower part of the eclipsed portion, and the
various small craters give it a stippled effect, like the old aqua-tint
engravings. The upper part is reddish, but two graceful bluish curves,
like horns, mark the form of the Hercynian mountains, and the bright
region on the other limb of the Moon. These are visible also to the
naked eye.
“At 3h. 5m. the redness had almost disappeared; a very few minutes
afterwards, no trace of it remained, and ere long clouds came on.
I watched the Moon, however, occasionally gaining a glimpse of its
disc, till a quarter to four o’clock, when, for the last time on that
occasion, I saw it faintly appearing through the clouds, nearly a full
Moon again; and then I took leave of it, feeling amply repaid for my
vigil by the beautiful spectacle which I had seen.”[14]
[14] The Hon. Mrs. Ward, Trimleston House, near Dublin, in
“Recreative Science,” p. 281.
Mr Walkey, who observed the lunar eclipse of March 19th, 1848, near
Collumpton, says--“The appearances were as usual till 20 minutes
past 9; at that period, and for the space of the next hour, instead
of an eclipse, or the shadow (umbra) of the Earth being the cause
of the total obscurity of the Moon, the whole phase of that body
became very quickly and most beautifully _illuminated_; and assumed
the appearance of the glowing heat of fire from the furnace, rather
tinged with a _deep red_. * * * The whole disc of the Moon being as
_perfect with light_ as if there had been _no eclipse whatever_! * *
* The Moon positively gave _good light from its disc during the total
eclipse_!”[15]
[15] “Philosophical Magazine,” No. 220, for August, 1848.
In the astronomical portion of the “Illustrated London Almanack
for 1864,” by Mr. Glaisher, a beautiful tinted engraving is given
representing the appearance of the Moon during the total eclipse
of June 1, 1863, when all the light and dark places--the so-called
mountains, seas, &c., were plainly visible. In the accompanying
descriptive chapter, the following sentences occur:--“At the time
of totality the Moon presented a soft woolly appearance, apparently
more globular in form than when fully illuminated. Traces of the
larger and brighter mountains were visible at the time of totality,
and particularly the bright rays proceeding from Tycho, Kepler, and
Aristarchus. * * * At first, when the obscured part was of small
dimensions, it was of an iron grey tint, but as it approached totality,
the reddish light became so apparent that it was remarked that the
Moon ‘seemed to be on fire;’ and when the totality had commenced, it
certainly looked like a fire smouldering in its ashes, and almost
going out.”
If then, the Sun and Moon have many times been seen above the horizon
when the latter was eclipsed, how can it be said that the Earth’s
shadow was the cause of a lunar eclipse, when the Earth was not between
or in a line with the Sun and Moon? And how can the Moon’s non-luminous
surface be distinctly visible and illuminated during the very totality
of an eclipse, if all the light of the Sun is intercepted by the Earth?
Again, if the Moon is a sphere, which it is declared to be, how can its
surface _reflect_ the light of the Sun? If her surface was a mass of
polished silver, it could not reflect from more than a mere point! Let
a silvered glass ball or globe of considerable size be held before a
lamp or fire of any magnitude, and it will be seen that instead of the
whole surface reflecting light, there will be a very small portion only
illuminated. But the Moon’s _whole surface_ is brilliantly illuminated!
a condition or effect utterly impossible if it be spherical. The
surface _might_ be _illuminated_ from the Sun, or any other source if
opaque, instead of polished, like an ordinary silvered mirror, but it
could not shine intensely from every part, and brightly illuminate the
objects before it, as the Moon does so beautifully when full and in
a clear firmament. If the Earth _were admitted_ to be globular, and
to move, and to be capable of throwing a shadow by intercepting the
light of the Sun, it would be impossible for a lunar eclipse to occur
thereby, unless at the same time the Moon be proved to be non-luminous,
and to shine only by reflection. But this is not proved; it is only
assumed as an essential part of a theory. The _contrary_ is capable
of proof, and proof beyond the power of doubt, viz., that the Moon
is _self-luminous_, or shines with a light peculiar to herself, and
therefore independently of the Sun. A reflector necessarily gives
off what it receives. If a mass of red-hot metal be placed before a
plane or concave surface, _heat_ will be reflected. If snow or ice
be similarly placed, _cold_ will be reflected. If light, ordinary or
coloured, be presented, the _same_ will be reflected. If sound of a
given pitch be produced, the same pitch will be reflected. If the
note A be sounded upon a musical instrument, a reflector would not
return the note B or C, but the _same note_, altered only in degree or
intensity, but not in “pitch.” A reflector receiving a red light would
not return a blue or yellow light. A reflector collecting the cold from
a mass of ice, would not throw off heat; nor the contrary. Nor could
the Moon, if a reflector, radiate or throw down upon the Earth any
other light than such as she receives from the Sun. No difference could
exist in the quality or character of the light, and it could differ in
no respect but the quantity or intensity.
The light of the Sun and of the Moon are different in their general
appearance--in the colour and action upon the eye.
The Sun’s light is drying and preservative, or antiseptic. The Moon’s
light is damp and putrefactive.
The Sun’s rays will put out a common fire; the Moon’s light will
increase the combustion. The light of the Sun falling upon certain
chemical substances, produces a change of colour, as in photographic
and other processes. The light of the Moon fails to produce the same
effect. Dr. Lardner, at page 121 of his excellent work, “The Museum of
Science,” says--“The most striking instance of the effect of certain
rays of solar light in blackening a light-colored substance, is
afforded by chloride of silver, which is a white substance, but which
immediately becomes black when acted upon by the rays near the violet
extremity of the spectrum. This substance, however, highly susceptible
as it is of having its colour affected by light, is, nevertheless,
found not to be changed in any sensible degree when exposed to the
light of the Moon, even when that light is condensed by the most
powerful burning lenses.”
The Sun’s light when concentrated by a number of mirrors, or a large
burning lens, produces a focus which is entirely non-luminous, but
in which the heat is so great that metallic and alkaline substances
are quickly fused; earthy and mineral compounds almost immediately
vitrified; and all animal and vegetable structures in a few seconds
burned up and destroyed. But the Moon’s light so concentrated produces
a brilliant focus, so luminous that it is difficult to look upon it;
and yet there is no increase of temperature! “If the most delicate
thermometer be exposed to the full light of the Moon, shining with its
greatest lustre, the mercury is not elevated a hair’s breadth, neither
would it be if exposed in the focus of her rays concentrated by the
most powerful lenses. This has been proved by actual experiment.”[16]
“This question has been submitted to the test of direct experiment. * *
* The bulb of a thermometer sufficiently sensitive to render apparent a
change of temperature amounting to the thousandth part of a degree, was
placed in the focus of a concave reflector of vast dimensions, which,
being directed to the Moon, the lunar rays were collected with great
power upon it. Not the slightest change, however, was produced in the
thermometric column, proving that a concentration of rays sufficient to
fuse gold, if they proceeded _from the Sun_, does not produce a change
of temperature so great as the thousandth part of a degree, when they
proceed _from the Moon_.”[17]
[16] “All the Year Round,” by Dickens.
[17] Dr. Lardner’s Museum of Science, p. 115.
“The light of the Moon though concentrated by the most powerful burning
glass, is incapable of raising the temperature of the most delicate
thermometer. M. De La Hire collected the rays of the full Moon when
on the meridian, by means of a burning glass thirty-five inches in
diameter, and made them fall on the bulb of a delicate air-thermometer.
_No effect was produced_, though the lunar rays by this glass were
concentrated 300 times.” “Professor Forbes concentrated the Moon’s
light by a lens thirty inches in diameter, its focal distance being
about forty-one inches, and having a power of concentration exceeding
6,000 times. The image of the Moon which was only eighteen hours past
full, and less than two hours from the meridian, was brilliantly thrown
by this lens on the extremity of a commodious thermo-pile. Although the
observations were made in the most unexceptional manner, and (supposing
that half the rays were reflected, dispersed, and absorbed) though the
light of the Moon was concentrated _3000 times, not the slightest
thermo-effect was produced_![18] In the “Lancet” (medical journal) for
March 14th, 1856, particulars are given of several experiments, which
proved that the Moon’s rays when concentrated actually _reduced_ the
temperature upon a thermometer more than 8 degrees!
[18] Dr. Noad’s Lectures on Chemistry, p. 334.
“The cold chaste Moon, the Queen
Of Heaven’s bright Isles;
Who makes all beautiful
On which she smiles:
That wandering shrine of soft
Yet _icy flame_,
Which ever is transformed
Yet still the same;
And _warms not_ but _illumes_.”
--SHELLEY.
The “pale _cold_ Moon” is an expression not only beautiful poetically
but evidently true philosophically.
If, as we have now seen, the very nature of a reflector demands certain
conditions and the Moon does not manifest these conditions, it must
of necessity be concluded that the Moon is _not_ a _reflector_, but
a _self-luminous body_. If self-luminous her surface could not be
darkened or eclipsed by a shadow of the Earth--supposing such were
thrown upon it. The luminosity instead of being diminished would be
greater in proportion to the greater density or darkness of the
shadow. As the light in a lantern shines most brightly in the darkest
places, so would the Moon’s self-luminous surface be most intense in
the deepest part of the Earth’s shadow. It is thus rendered undeniable
that a Lunar Eclipse _does_ not and _could_ not arise from a shadow of
the Earth! As a _Solar_ Eclipse occurs from the Moon passing over the
Sun; so from the evidence it is clear that a Lunar Eclipse _can only_
arise from a similar cause--a body semi-transparent and well-defined
passing before the Moon, or between her surface and the observer on the
surface of the Earth. That such a body exists is admitted by several
distinguished astronomers. In the report of the Council of the Royal
Astronomical Society for June, 1850, it is stated, “We may well doubt
whether that body which we call the Moon is the _only satellite_ of
the Earth.” In the report of the Academy of Sciences for October 12,
1846, and again for August, 1847, the Director of one of the French
Observatories gives a number of observations and calculations which
have led him to conclude that “there is at least _one non-luminous
body_ of considerable magnitude which is attached as a _satellite to
this Earth_.”[19]
[19] Referred to in Lardner’s “Museum of Science,” p. 159.
Persons who are unacquainted with the methods of calculating Eclipses
and other astronomical phenomena, are prone to look upon the
correctness of these calculations as powerful arguments in favour of
the doctrine of the Earth’s rotundity and the Newtonian philosophy
generally. But this is erroneous. Whatever theory is adopted, or if
all theories are discarded, the same results may follow, because the
necessary data may be tabulated and employed independently of all
theory, or may be mixed up with any, even the most opposite doctrines,
or kept distinct from every system, just as the operator may decide.
The tables of the Moon’s relative positions for almost any second of
time are purely practical, the result of long continued observation,
and may or may not be mixed up with hypothesis. In Smith’s “Rise and
progress of Astronomy,” speaking of Ptolemy, who lived in the 2nd
century of the Christian Era, it is said, “The (considered) defects of
his system did not prevent him from calculating all the Eclipses that
were to happen for 600 years to come.” Professor Partington, at page
370 of his Lectures on Natural Philosophy, says, “The most ancient
observations of which we are in possession, that are sufficiently
accurate to be employed in astronomical calculations, are those made
at Babylon about 719 before the Christian Era, of three Eclipses of
the Moon. Ptolemy, who has transmitted them to us, employed them for
determining the period of the Moon’s mean motion; and therefore had
probably none more ancient on which he could depend. The Chaldeans,
however, must have made a long series of observations before they could
discover their “Saros” or lunar period of 6,585¹⁄₃ days, or about 18
years; at which time, as they had learnt, the place of the Moon, her
_node_ and _apogee_ return nearly to the same situation with respect
to the Earth and the Sun, and, of course, a series of nearly similar
Eclipses occur.”
Sir Richard Phillips, in his “Million of Facts,” at page 388,
says:--“The precision of astronomy arises, not from theories, but from
prolonged observations, and the regularity of the motions, or the
ascertained uniformity of their irregularities. Ephemerides of the
planets’ places, of Eclipses, &c., have been published for above 300
years, and were nearly as precise as at present.”
“No particular theory is required to calculate Eclipses; and the
calculations may be made with equal accuracy _independent of every
theory_.”[20]
[20] Somerville’s Physical Sciences, p. 46.
SECTION 10.
CAUSE OF TIDES.
The doctrine of the Earth’s rotundity being fallacious, all ideas of
“centre of attraction of gravitation,” “mutual attraction of Earth and
Moon,” &c., &c., must be given up; and the cause of tides in the ocean
must be sought for in another direction. It is certain that there is
a constant pressure of the atmosphere upon the surface of the Earth
and ocean. This is proved by ordinary barometrical observations, many
Pneumatic experiments, and by the fact that during the most fearful
storms at sea the surface only is disturbed; at the depth of a hundred
feet the water is always calm--except in the path of well-marked
currents and local submarine phenomena. The following quotations
gathered from casual reading fully corroborate this statement. “It is
amazing how superficial is the most terrible tempest. Divers assure
us that in the greatest storms calm water is found at the depth of 90
feet.”[21]
[21] Chambers’s Journal, No. 100, p. 379.
“This motion of the surface of the sea is not perceptible to a great
depth. In the strongest gale it is supposed not to extend beyond
72 feet below the surface; and at the depth of 90 feet the sea is
perfectly still.”[22]
[22] Penny Cyclopædia, Article Sea.
“The people are under a great mistake who believe that the substance of
the water moves to any considerable depth in a storm at sea. It is only
the form or shadow which hurries along like a spirit, or like a thought
over the countenance of the ‘great deep,’ at the rate of some forty
miles an hour. Even when the ‘Flying Dutchman’ is abroad the great mass
of water continues undisturbed and nearly motionless a few feet below
the surface.”[23]
[23] London Saturday Journal, August 8, 1840, p. 71.
“The unabraded appearance of the shells brought up from great depths,
and the almost total absence of the mixture of any _detritus_ from the
sea, or foreign matter, suggest most forcibly the idea of _perfect
repose_ at the bottom of the deep sea.”[24]
[24] Physical Geography of the Sea, by Lieut. Maury, p. 265.
Bearing this fact in mind, that there exists a continual pressure of
the atmosphere upon the Earth, and associating it with the fact that
the Earth is a vast plane “stretched out upon the waters,” and it will
be seen that it must of necessity slightly fluctuate, or slowly rise
and fall in the water. As by the action of the atmosphere the Earth
is slowly depressed, the water moves towards the receding shores and
produces the flood tide; and when by the reaction of the resisting
oceanic medium the Earth gradually ascends the waters recede, and the
ebb tide is produced. This is the _general_ cause of tides. Whatever
peculiarities are observable they may be traced to the reaction of
channels, bays, headlands, and other local causes.
If a raft, or a ship, or any other structure floating upon water be
carefully observed, it will be seen to have a gentle fluctuating
motion. However calm the water and the atmosphere may be, this
gradual rising and falling of the floating mass is always more or
less observable. If vessels of different sizes are floating near each
other they will be seen to fluctuate with different velocities, the
largest and heaviest will move the least rapidly. This motion will be
observable whether the vessels be held by their anchors, or moored to
buoys, or freely floating in still water. A large and heavily laden
vessel will make several fluctuations in a minute of time; the Earth
once only in about twelve hours, because it is proportionately larger.
To this simple condition of the Earth,--the action or pressure upon
it of the atmosphere, and the reaction or resistance to it of the
water, may be traced all the leading peculiarities of the tides.
The simultaneous ebb and flow upon meridians 180° apart. The absence
of high and low water in large inland seas and lakes; which being
contained within and fluctuating with the Earth cannot therefore show
a relative change in the altitude of the surface. The flux and reflux
observed in several inland wells and basins though far from the sea,
but being connected with it by subterranean passages, necessarily show
a relative difference in the surface levels of the earth and water. And
the regular ebb and flood of the water in the great Polar sea recently
discovered by Dr. Kane, although it is separated from the great tidal
current of the Atlantic Ocean by deep barriers of ice--as will be seen
by the following quotation:--“Dr. Kane reported an open sea north of
the parallel of 82°. To reach it his party crossed a barrier of ice
80 or 100 miles broad. Before gaining this open water he found the
thermometer to show the extreme temperature of -60°. Passing this
ice-bound region by travelling North, he stood on the shores of an
iceless sea extending in an unbroken sheet of water as far as the eye
could reach towards the pole. Its waves were dashing on the beach with
the swell of a boundless ocean. The tides ebbed and flowed in it, and I
apprehend that the tidal wave from the Atlantic can no more pass under
this icy barrier to be propagated in seas beyond than the vibrations
of a musical string can pass with its notes a ‘fret’ upon which the
musician has placed his finger. * * * These tides therefore must have
been born in that cold sea, having their cradle about the North Pole;
and we infer that most, if not all, the unexplored regions about the
Pole are covered with deep water; for, were this unexpected area mostly
land, or shallow water, it could not give birth to regular tides.”[25]
[25] Physical Geography of the Sea, by Lieut. Maury, p. 176.
That the Earth has a vibratory or tremulous motion, such as must
necessarily belong to a floating and fluctuating structure, is
abundantly proved by the experience of astronomers and surveyors.
If a delicate spirit-level be firmly placed upon a rock or upon the
most solid foundation which it is possible to construct, the very
curious phenomenon will be observed of constant change in the position
of the air-bubble. However carefully the “level” may be adjusted,
and the instrument protected from the atmosphere, the “bubble”
will not maintain its position many seconds together. A somewhat
similar influence has been noticed in astronomical observatories,
where instruments of the best construction and placed in the most
approved positions cannot always be relied upon without occasional
re-adjustment.
SECTION 11.
CONSTITUTION, CONDITION, AND ULTIMATE DESTRUCTION OF THE EARTH BY FIRE.
Chemical analysis proves to us the important fact that the great
bulk of the Earth--meaning thereby the _land_ as distinct from the
waters--is composed of metallic oxides or metals in combination with
oxygen. When means are adopted to remove the oxygen it is found that
most of these metallic bases are highly combustible. The different
degrees of affinity existing among the elements of the Earth, give rise
to all the rocks, minerals, ores, deposits, and strata which constitute
the material habitable world. The different specific gravities or
relative densities which these substances are found to possess, and the
numerous evidences which exist of their former plastic or semi-fluid
condition, afford positive proof that from a once commingled or chaotic
state regular but rapid precipitation, stratification, crystallization,
and concretion successively occurred; and that in some way not yet
clear to us sufficient chemical action was produced to ignite a great
portion of the Earth, and to reduce it to a molten incandescent state,
the volatile products of which being forcibly eliminated have broken
up the stratified formations, and produced the irregular confused
condition which we now observe. That such an incandescent molten
state of a great portion of the lower parts of the Earth still exists
is a matter of certainty; and there is evidence that the heat thus
internally generated is gradually increasing.
“The uppermost strata of the soil share in all the variations of
temperature which depend upon the seasons; and this influence is
exerted to a depth which, although it varies with the latitude, is
never very great. Beyond this point the temperature rises in proportion
as we descend to greater depths, and it has been shown, by numerous
and often-repeated experiments, that the increase of temperature is
on average one degree (Fahrenheit) for about every 545 feet. Hence it
results that at a depth of about twelve miles from the surface, we
should be on the verge of an incandescent mass.”[26]
[26] Rambles of a Naturalist, by M. de Quatrefages.
“So great is the heat within the Earth, that in Switzerland, and other
countries where the springs of water are very deep, they bring to the
surface the warm mineral waters so much used for baths and medicine for
the sick; and it is said, that if you were to dig very deep down into
the Earth, the temperature would increase at the rate of one degree
of the thermometer for every 100 feet; so that, at the depth of 7000
feet, or one mile and a half, all the water that you found would be
boiling; and at the depth of about ten miles all the rocks would be
melted. * * * A day will yet come when this earth will be burned up by
the fire. There is fire, as you have heard, within it, ready to burst
forth at any moment.”[27] “This earth, although covered all round with
a solid crust, is all on fire within. Its interior is supposed to be a
burning mass of melted, glowing metals, fiery gas, and boiling lava.
* * * * * The solid crust which covers this inward fire is supposed
not to be much more than from 9 to 12 miles in thickness. Whenever
this crust breaks open, or is cleft in any place, there rush out lava,
fire, melted rocks, fiery gases, and ashes, sometimes in such floods as
to bury whole cities. From time to time we read of the earth quaking,
trembling, and sometimes opening, and of mountains and small islands
(which are mountains in the sea) being thrown up in a day.”[28]
[27] “The World’s Birthday,” by Professor Gaussen, Geneva, p. 43.
[28] “The World’s Birthday,” by Professor Gaussen, Geneva, p. 42.
In a periodical called “Recreative Science,” at the end of an
interesting article on volcanoes, &c., the following sentence
occurs:--“The conclusion is therefore inevitable, that the general
distribution all over the earth of volcanic vents, their similarity of
action and products, their enormous power and seeming inexhaustibility,
their extensiveness of action in their respective sites, the
continuance of their energies during countless years, and the incessant
burning day and night, from year to year, of such craters as Stromboli;
and lastly, the apparent inefficiency of external circumstances in
controlling their operations, eruptions happening beneath the sea as
beneath the land, in the frigid as in the torrid zone, for these and
many less striking phenomena, we must seek for some great and general
cause, such only as the central heat of the earth affords us.”
Sir Richard Phillips says, “at the depth of 50 feet (from the sea
level) the temperature of the earth is the same winter and summer.”
* * * “The deepest coal mine in England is at Killingworth, near
Newcastle-upon-Tyne, and the mean annual temperature at 400 yards below
the surface is 77°; and at 300 yards, 70°; while at the surface it is
but 48°, being about one degree of increase for every 15 yards. Hence,
at 3,300 yards, the heat would be equal to boiling water, taking 20
yards to a degree. This explains the origin of hot springs. The heat of
the Bath waters is 116°, hence they would appear to rise from a depth
of 1,320 yards. By experiments made at the Observatory of Paris for
ascertaining the increase of temperature from the surface of the earth
towards the interior, 51 feet, or 17 yards, corresponds to the increase
of one degree Fahrenheit’s thermometer. Hence, the temperature of
boiling water would be at 8,212 feet, or about 1¹⁄₂ English miles under
Paris.”
Professor Silliman, of America, states “that in boring the Artesian
wells in Paris, the temperature increased at the rate of 1 degree for
every 50 feet downwards; and, reasoning from causes known to exist, the
whole of the interior part of the earth, or, at least, a great part of
it, is an ocean of melted rock agitated by violent winds.”
Sir Charles Lyell, in his address to the British Association, assembled
at Bath, September, 1864, speaking of hot springs generally, said “An
increase of heat is always experienced as we descend into the interior
of the earth. * * * The estimate deduced by Mr. Hopkins, from an
accurate series of observations made in the Monkwearmouth shaft, near
Durham, and in the Dukenfield shaft, near Manchester, each of them
2,000 feet in depth. In these shafts the temperature was found to rise
at the rate of 1° Fah. for every increase of depth of from 65 to 70
feet.”
“The observations made by M. Arago, in 1821, that the deepest Artesian
wells are the warmest, threw great light on the origin of thermal
springs, and on the establishment of the law, that terrestrial heat
increases with increasing depth. It is a remarkable fact, which has
but recently been noticed, that at the close of the third century St
Patricius, probably Bishop of Partusa, was led to adopt very correct
views regarding the phenomenon of the hot springs at Carthage. On being
asked what was the cause of boiling water bursting from the earth,
he replied, ‘Fire is nourished in the clouds, and in the interior of
the earth, as Etna and other mountains near Naples may teach you.
The subterranean waters rise as if through siphons. The cause of hot
springs is this: waters which are more remote from the subterranean
fire are colder, whilst those which rise nearer the fire, are heated
by it, and bring with them to the surface which we inhabit, an
insupportable degree of heat.’”[29]
[29] “Humboldt’s Cosmos,” p. 220.
The investigations which have been made, and the evidence which has
been brought together, render it undeniable that the lower parts of the
earth are on fire. Of the intensity of the combustion, no practical
idea can be formed. It is fearful beyond comparison. The lava thrown
out from a volcano in Mexico, “was so hot that it continued to smoke
for twenty years; and after three years and a half, a piece of wood
took fire in it, at a distance of five miles from the crater.” In
various parts of the world, large islands have been thrown up from the
sea, in a red-hot glowing condition, and so intensely heated, that
after being forced through many fathoms of salt water, and standing
in the midst of it, exposed to wind and rain for several months,
they were not sufficiently cooled for persons to approach and stand
upon them. “A notable fact is the force exerted in volcanic action,
Cotopaxi, in 1738, threw its fiery rockets 3,000 feet above its crater,
while in 1744 the blazing mass, struggling for an outlet, roared like
a furnace, so that its awful voice was heard at a distance of more
than six hundred miles. In 1797, the crater of Tunguragua, one of the
great peaks of the Andes, flung out torrents of mud, which dammed up
rivers, opened new lakes, and in valleys of a thousand feet wide made
deposits six hundred feet deep. The stream from Vesuvius which, in
1737, passed through Torre del Greco, contained thirty-three million
cubic feet of solid matter; and, in 1794, when Torre del Greco was
destroyed a second time, the mass of lava amounted to forty-five
million cubic feet. In 1669 Etna poured forth a flood which covered 84
square miles of surface, and measured nearly 100,000,000 cubic feet.
On this occasion the sand and scoriæ formed the Monte Rossi, near
Nicolosi, a cone two miles in circumference, and four hundred and fifty
feet high. The stream thrown out by Etna, in 1819, was in motion, at
the rate of a yard per day, for nine months after the eruption; and
it is on record that the lavas of the same mountain, after a terrible
eruption, were not thoroughly cooled and consolidated ten years after
the event. In the eruption of Vesuvius, A.D. 79, the scoriæ and ashes
vomited forth far exceeded the entire bulk of the mountain; while,
in 1660, Etna disgorged more than twenty times its own mass. * * *
Vesuvius has thrown its ashes as far as Constantinople, Syria, and
Egypt; it hurled stones eight pounds in weight to Pompeii, a distance
of six miles; while similar masses were tossed up 2,000 feet above
its summit. Cotopaxi has projected a block one hundred cubic yards in
volume a distance of nine miles, while Sumbawa, in 1815, during the
most terrible eruption on record, sent its ashes as far as Java, a
distance of three hundred miles. * * * In viewing these evidences of
enormous power, we are forcibly struck with the similarity of action
with which they have been associated; and, carrying our investigation
a step further, the same similarity of the producing power is hinted
at in the identity of the materials ejected. Thus, if we classify
the characteristics of all recorded eruptions, we shall find that
the phenomena are all reducible to upheavals of the earth, rumblings
and explosions, ejections of carbonic acid, fiery torrents of lava,
cinders, and mud, with accompanying thunder and lightning. The
last-named phenomena are extrajudicial in character; they are merely
the result of the atmospheric disturbance consequent on the escape of
great heat from the earth, just as the burning of an American forest
causes thunder and rain. The connection that apparently exists, too,
between neighbouring craters is strongly confirmed by the fact that
in every distinct volcanic locus but _one_ crater is usually active
at a time. Since Vesuvius has resumed his activity, the numerous
volcanic vents on the other side of the bay have sunk into comparative
inactivity; for ancient writers, who are silent respecting the former,
speak of the mephitic vapours of the Lake Avernus as destructive to
animal existence, and in earlier days than these Homer pictures the
Phlegrean Fields as the entrance to the infernal regions, placed at the
limits of the habitable world, unenlightened by rising or setting sun,
and enveloped in eternal gloom. * * * * The earth contains within it
a mass of heated material; nay, it is a heated and incandescent body,
habitable only because surrounded with a cool crust--the crust being
to it a mere shell, within which the vast internal fires are securely
inclosed: and yet not securely, perhaps, unless such vents existed as
those to which we apply the term volcano. * * * * Every volcano is
a safety-valve, ready to relieve the pressure from within when that
pressure rises to a certain degree of intensity; or permanently serving
for the escape of conflagrations, which, if not so provided with
escape, might rend the habitable crust to pieces.”[30]
[30] Recreative Science, p.p. 257 to 260.
Thus it is certain, from the phenomena of earthquakes, submarine and
inland volcanoes which exist in every part of the earth from the frozen
to the tropical regions, hot and boiling springs, fountains of mud
and steam, lakes of burning sulphur, jets and blasts of destructive
gases, and the choke and fire damps of our coal mines, that at a few
miles only below the surface of the earth there exists a vast region of
combustion, the intensity and power of which are indescribable, and
cannot be compared with anything within the range of human experience.
As the earth is an extended plane resting in and upon the waters of
the “great deep” it may fitly be compared to a large vessel or ship
floating at anchor, with her “Hold” or lower compartments beneath the
water-line filled with burning materials; and, from our knowledge of
the nature and action of fire, it is difficult to understand in what
way the combustion can be prevented from extending, when it is known
to be surrounded with highly inflammable substances. Wherever a fire
is surrounded with heterogeneous materials--some highly combustible
and others partially and indirectly combustible--it is not possible
for it to remain continually in the same condition nor to diminish in
extent and intensity, it must increase and extend itself. That the fire
in the earth is so surrounded with inflammable materials is matter of
certainty; the millions of tons of coals, peat, turf, mineral oils,
rock tar, pitch, asphalte, bitumen, petroleum, mineral naphtha, and
numerous other hydro-carbons which exist in various parts of the earth,
and much of these far down below the surface, prove this condition
to exist. The products of volcanic action being chiefly carbon in
combination with hydrogen and oxygen, prove also that these carbon
compounds already exist in a state of combustion, and that as such
immense quantities of the same fuel still exist, it is quite within
the range of possibility that some of the lower strata of combustible
matter may take fire and the action rapidly extend itself through
the various and innumerable veins which ramify in every direction
throughout the whole earth. Should such an action commence, knowing,
as we do, that the rocks and minerals of the earth are but oxides of
inflammable bases, and that the affinities of these bases are greatly
weakened and almost suspended in the presence of highly heated carbon,
we see clearly that such chemical action or fire would quickly extend
and increase in intensity until the whole earth with everything
entering into its composition, would rapidly decompose, volatilise, and
burst into one vast indescribable, annihilating conflagration!
SECTION 12.
MISCELLANEA.
MOON’S PHASES.--It has been shown that the Moon is not a reflector of
the Sun’s light, but is self-luminous. That the luminosity is confined
to one-half its surface is sufficiently shown by the fact that at “New
Moon” the whole circle or outline of the Moon is often distinctly
visible; but the darker outline is less, or the circle is smaller than
the segment which is illuminated. From this it is easily seen that
“New Moon,” “Full Moon,” and “Gibbous Moon” are but the different
proportions of the illuminated surface which are presented to the
observer on earth.
MOON’S APPEARANCE.--Astronomers have indulged their imagination to
such a degree that the Moon has been considered to be a solid, opaque,
spherical world, having mountains, valleys, lakes, volcanic craters,
and other conditions analogous to the surface of the earth. So far has
this fancy been carried, that the whole visible disc has been mapped
out, and special names given to its various peculiarities, as though
they had been carefully observed and measured by a party of terrestrial
ordnance surveyors. All this has been done in direct opposition to the
fact that whoever looks, without previous bias, through a powerful
telescope at the Moon’s surface, will be puzzled to say what it is
really like, or how to compare it with anything known. The comparison
which may be made, will depend greatly upon the state of mind of the
observer. It is well known that persons looking at the rough bark of
a tree, or at the irregular lines or veins in certain kinds of marble
and stone, or gazing at the red embers in a dull fire, will, according
to the degree of activity of the imagination, be able to see different
forms, even the outlines of animals and human faces. It is in this way
that persons may fancy that the Moon’s surface is broken up into hills
and valleys and other arrangements such as are found on earth. But that
anything really similar to the surface of our own world is anywhere
visible upon the Moon is altogether fallacious. This is admitted by
some of those who have written upon the subject “Some persons when
they look into a telescope for the first time, having heard that
mountains are to be seen, and discovering nothing but these (previously
described) unmeaning figures, break off in disappointment, and have
their faith in these things rather diminished than increased. I would
advise, therefore, before the student takes even his _first view_ of
the Moon through a telescope, to form as clear an idea as he can how
mountains, and valleys, and caverns situated at such a distance _ought_
to look, and by what marks they may be recognised. Let him seize, if
possible, the most favourable periods (about the time of the first
quarter), and previously _learn from drawings_ and explanations how to
_interpret_ everything he sees.”[31] “Whenever we exhibit celestial
objects to inexperienced observers it is usual to precede the view with
good _drawings_ of the objects, accompanied by an explanation of what
each appearance exhibited in the telescope _indicates_. The novice is
told that mountains and valleys can be seen in the Moon by the aid
of the telescope; but on looking he sees a confused mass of light
and shade, and _nothing_ which _looks_ to him _like either mountains
or valleys_! Had his attention been previously directed to a plain
_drawing_ of the Moon, and each particular appearance _interpreted_ to
him, he would then have looked through the telescope with intelligence
and satisfaction!”[32] Thus it is admitted by those who teach that the
Moon is a spherical world, having hills and dales like the earth, can
only see such things in imagination. “Nothing but unmeaning figures”
are really visible, and “the students break off in disappointment, and
have their faith in such things rather diminished than increased,”
“until they previously learn from _drawings_ and explanations how to
_interpret_ everything seen.” But who _first made_ the drawings? Who
_first interpreted_ the “unmeaning figures” and the “confused mass
of light and shade?” Who first declared them to indicate mountains
and valleys, and ventured to make drawings and give explanations and
interpretations for the purpose of biasing the minds, and fixing or
guiding the imaginations of subsequent observers? Whoever they were,
they at least had “given the reins to Fancy,” and afterwards took
upon themselves to dogmatise and teach their crude and unwarranted
imaginings to succeeding investigators. And this is the kind of
evidence and “reasoning” which is obtruded in our seats of learning,
and spread out in the numerous works which are published for the
edification of society!
[31] “Mechanism of the Heavens,” by Denison Olmsted, LL.D., Professor
of Natural Philosophy and Astronomy in Gale College, U.S.
[32] Mitchell’s “Orbs of Heaven,” p. 232.
THE PLANET NEPTUNE.--For some years the advocates of the earth’s
rotundity, and of the Newtonian philosophy generally, were accustomed
to refer with an air of pride and triumph to the discovery of a
new planet, which was called Neptune, as an undeniable evidence of
the truth of their system or theory. The existence of this luminary
was said to have been predicated from calculation only, and for a
considerable period before it had been seen by the telescope. It
was urged that therefore the system which would permit of such a
discovery must be true. But the whole matter subsequently proved to
be unsatisfactory. That a proper conception may be formed of the
actual value of the calculations and their supposed verification,
the following account will be useful. “In the year 1781, on March
13, Uranus was discovered by Sir William Herschel, who was examining
some small stars near the feet of Gemini; and he observed one of them
to have a sensible amount of diameter and less brightness than the
others, and it was soon found to be a planet. It, however, had been
seen before--first, by Flamstead, on December 23rd, 1690; and between
this time and 1781 it had been observed 16 times by Flamstead, Bradley,
Mayer, and Lemonnier; these astronomers had classed it as a star of the
sixth magnitude. Between 1781 and 1820 it was of course very frequently
observed; and it was hoped that at the latter time sufficient data
existed to construct accurate tables of its motions. This task was
undertaken by M. Bouvard, Member _de L’Academie des Sciences_, but he
met with unforeseen difficulties. It was found utterly impossible to
construct tables which would represent the 17 ancient observations,
and at the same time the more numerous modern ones; and it was finally
concluded that the ancient observations were erroneous, or that some
strange and unknown action disturbed, or had disturbed, the planet;
consequently M. Bouvard discarded entirely the old observations, and
used only those taken between 1781 and 1820, in constructing the tables
of Uranus. For some years past it has been found that the tables thus
constructed do not agree any better with modern observations, than they
do with the ancient observations; _consequently it was evident that
the planet was under the influence of some unknown cause_. Several
hypotheses have been suggested as to the nature of this cause; some
persons talked of a resisting medium; others of a great satellite which
might accompany Uranus; some even went so far as to suppose that the
vast distance Uranus is from the Sun caused the law of gravitation to
lose some of its force; others thought that the rapid flight of a comet
had disturbed its regular movements; others thought of the existence of
a planet beyond Uranus, whose disturbing force caused the anomalous
motions of the planet; but no one did otherwise than follow the bent
of his inclination, and did not support his assertion by any positive
considerations.
“Thus was the theory of Uranus surrounded with difficulties, when M.
Le Verrier, an eminent French mathematician, undertook to investigate
the irregularities in its motions. His first paper appeared on the
10th November, 1845, and his second on June 1, 1846 (published in
the Comptes Rendûs). In this second paper, after a most elaborate
and careful investigation, he proves the utter incompatibility of
any of the preceding hypotheses to account for the planet’s motions,
except only that of the last one, viz., that of a new planet. He then
successively proves that this planet cannot be situated either between
the Sun and Saturn, or between Saturn and Uranus; but that it must be
beyond Uranus. And in this paper he asks the following questions:--‘Is
it possible that the irregularities of Uranus can be owing to the
action of a planet situated in the ecliptic, at a distance of twice
the mean distance of Uranus from the Sun? If so, where is it actually
situated? What is its mass? What are the elements of the orbit it
describes?”
This was the problem he set himself to work upon, by the means of
solving the inverse problem of the perturbations; for instead of
having to measure the action of a determined planet, he had to deduce
the elements of the orbit of the disturbing planet, and its place
in the heavens from the recognised inequalities of Uranus. And this
problem M. Le Verrier has successfully solved. In his second paper
he deduces the place in the heavens that the body must be as 325° of
helio-centric longitude. On the 31st August last he published his third
paper. In this he has calculated that the period of the planet is 217
years; and that it moves in an orbit at the distance of more than 3,000
millions of miles from the Sun; that its mean longitude on January
1st, 1847, will be 318° 17′; its true longitude 326° 32′; and that the
longitude of its perihelion will be 284° 45′; that it will appear to
have a diameter of 3¹⁄₄ seconds of arc as seen from the earth; and that
it is now about 5° E. of _Delta Capricorni_.
“These remarkable calculations have pointed out a position which has
very nearly proved to be the true one.
“On September 23, Dr. Galle at Berlin discovered a star of the eighth
magnitude, which has proved to be the planet. Its place at the time was
five degrees from _Delta Capricorni_. It was found to have a disc of 3
seconds as predicted; and its longitude at the time differs less than a
degree from the longitude computed from the above elements. Its daily
motion, too, is found to agree very closely with the predicted; and,
judging from this last circumstance, the planet’s distance, as stated
above, must be nearly the truth.
“Thus the result of these calculations was the discovery of a new
planet in the place assigned to it by theory, whose mass, distance,
position in the heavens, and orbit it describes round the Sun, were all
approximately determined before the planet had ever been seen; and all
agrees with observations, so far as can at present be determined. It is
found to have a disc, and its diameter cannot be much less than 40,000
miles, and may be more; its motions are very slow; it is at present in
the constellation of Aquarius as indicated by theory; and it will be in
the constellation of Capricornus all the year 1847. It may be readily
seen in a telescope of moderate power.
“Whatever view we take of this noble discovery it is most gratifying,
whether at the addition of another planet to our list; whether at the
proving the correctness of the theory of universal gravitation; or in
what view soever, it must be considered as a splendid discovery, and
the merit is chiefly due to theoretical astronomy. This discovery is
perhaps the greatest triumph of astronomical science that has ever
been recorded.”[33]
[33] “Illustrated London Almanack for 1847.”
If such things as criticism, experience, and comparative observation
did not exist, the tone of exultation in which the above article
indulges might be properly shared in by the astronomical student; but
let the following extracts be carefully read, and it will be seen that
such a tone was premature and unwarranted. “Paris, Sept. 15, 1848.
The only sittings of the Academy of late in which there was anything
worth recording, and even this was not of a practical character, were
those of the 29th ult. and the 11th inst. On the former day M. Babinet
made a communication respecting the planet Neptune, which has been
generally called M. Le Verrier’s planet, the discovery of it having,
as it was said, been made by him from theoretical deductions, which
astonished and delighted the scientific public. What M. Le Verrier had
inferred from the action on other planets of some body which ought to
exist was verified, at least so it was thought at the time, by actual
vision. Neptune was actually seen by other astronomers, and the honour
of the theorist obtained additional luster. But it appears from a
communication of M. Babinet that _this is not the planet_ of M. Le
Verrier. He had placed his planet at a distance from the Sun equal to
thirty-six times the limit of the terrestrial orbit; Neptune revolves
at a distance equal to thirty times of these limits, which makes a
difference of nearly _two hundred millions of leagues_! M. Le Verrier
had assigned to his planet a body equal to thirty-eight times that of
the earth; Neptune has only _one third_ of this volume! M. Le Verrier
had stated the revolutions of his planet round the Sun to take place
in two hundred and seventeen years; Neptune performs its revolutions
in one hundred and sixty-six years! Thus then Neptune is not M. Le
Verrier’s planet; and all his theory as regards that planet falls to
the ground! M. Le Verrier may find another planet, but it will not
answer the calculations which he had made for Neptune. In the sitting
of the 14th, M. Le Verrier noticed the communication of M. Babinet, and
to a great extent admitted his own error! He complained indeed that
much of what he said was taken in too absolute a sense; but he evinces
much more candour than might have been expected from a disappointed
explorer. M. Le Verrier may console himself with the reflection that
if he has not been so successful as he thought he had been, others
might have been equally unsuccessful, and as he has still before him
an immense field for the exercise of observation and calculation, we
may hope that he will soon make some discovery which will remove the
vexation of his present disappointment.”[34]
[34] “Times” Newspaper, Monday, Sept. 18, 1848.
“As the data of Le Verrier and Adams stand at present there is a
discrepancy between the predicted and the true distance; and in some
other elements of the planet. It remains, therefore, for these or
future astronomers to reconcile theory with fact; or, perhaps, as
in the case of Uranus, to make the new planet the means of leading
to yet greater discoveries. It would appear, from the most recent
observations, that the mass of Neptune, instead of being as at first
stated one nine thousand three hundredth is only one twenty three
thousandth that of the Sun; whilst its periodic time is now given
with a greater probability at 166 years; and its mean distance from
the Sun nearly thirty. Le Verrier gave the mean distance from the Sun
thirty-six times that of the Earth; and the period of revolution 217
years.[35]
[35] “Cosmos,” by Humboldt, p. 75.
“May 14, 1847. A Paper was read before the Royal Astronomical Society,
by Professor Schumacher, ‘on the identity of the planet Neptune (M. Le
Verrier’s) with a star observed by M. Lalande in May, 1795.’”[36]
[36] “Report of Royal Astronomical Society,” for Feb. 11, 1848, No. 4,
vol. 8.
Such mistakes as the above ought at least to make the advocates of the
Newtonian theory less positive, and more ready to acknowledge that at
best their system is but hypothetical and must sooner or later give
place to a philosophy the premises of which are demonstrable, and which
is in all its details sequent and consistent.
PENDULUM EXPERIMENTS AS PROOFS OF EARTH’S MOTION.
In the early part of the year 1851, the scientific journals and nearly
all the newspapers published in Great Britain and on the Continents of
Europe and America were occupied in recording and discussing certain
experiments with the pendulum, first made by M. Foucault, of Paris; and
the public were startled by the announcement that the results furnished
a practical proof of the Earth’s rotation.
The subject was referred to in the _Literary Gazette_, in the following
words:--“Everybody knows what is meant by a pendulum in its simplest
form, a weight hanging by a thread to a fixed point. Such was the
pendulum experimented upon long ago by Galileo, who discovered the
well-known law of isochronous vibrations, applicable to the same. The
subject has since received a thorough examination, as well theoretical
as practical, from mathematicians and mechanicians; and yet, strange
to say, the most remarkable feature of the phenomenon has remained
unobserved and wholly unsuspected until within the last few weeks, when
a young and promising French physicist, M. Foucault, who was induced by
certain reflections to repeat Galileo’s experiments in the cellar of
his mother’s house at Paris, succeeded in establishing the existence
of a fact connected with it which gives an immediate and visible
demonstration of the Earth’s rotation. Suppose the pendulum already
described to be set moving in a vertical plane from north to south,
the plane in which it vibrates, to ordinary observation, would appear
to be stationary. M. Foucault, however, has succeeded in showing that
this is not the case, but that the plane is itself slowly moving round
the fixed point as a centre in a direction contrary to the Earth’s
rotation, _i.e._, with the apparent heavens, from east to west. His
experiments have since been repeated in the hall of the observatory,
under the superintendence of M. Arago, and fully confirmed. If a
pointer be attached to the weight of a pendulum suspended by a long and
fine wire, capable of turning round in all directions, and nearly in
contact with the floor of a room, the line which this pointer appears
to trace on the ground, and which may easily be followed by a chalk
mark, will be found to be slowly, but visibly, and constantly moving
round, like the hand of a watch dial; and the least consideration will
show that this ought to be the case, and will excite astonishment that
so simple a consequence as this is, of the most elementary laws of
Geometry and Mechanics, should so long have remained unobserved. * *
* The subject has created a great sensation in the mathematical and
physical circles of Paris. It is proposed to obtain permission from
the Government to carry on further observations by means of a pendulum
suspended from the dome of the Pantheon, length of suspension being
a desideratum in order to make the result visible on a larger scale,
and secure greater constancy and duration in the experiment. The time
required for the performance of a complete revolution of the plane of
vibration would be about 32 hours 8 minutes for the parallel of Paris;
30 hours 40 minutes for that of London; and at 30 degrees from the
equator exactly 48 hours. Certainly any one who should have proposed
not many weeks back to prove the rotation of the Earth upon which we
stand by means of direct experiment made upon its surface would have
run the risk, with the mob of gentlemen who write upon mechanics, of
being thought as mad as if he were to have proposed reviving Bishop
Wilkins’s notable plan for going to the North American colonies in a
few hours, by rising in a balloon from the Earth and gently floating
in the air until the Earth, in its diurnal rotation, have turned the
desired quarter towards the suspended æronaut, whereupon as gently to
descend; so necessary and wholesome is it occasionally to reconsider
the apparently simplest and best established conclusions of science.”
The following is from the _Scotsman_, which has always been
distinguished for the accuracy of its scientific papers. The article
bears the initials “C. M.,” which will at once be recognised as those
of Mr. Charles Maclaren, for many years the accomplished editor of
that journal:--“The beautiful experiment contrived by M. Foucault
to demonstrate the rotation of the globe, has deservedly excited
universal interest. * * * A desire has always been felt that some
method could be devised of rendering this rotation palpable to the
senses. Even the illustrious Laplace participated in this feeling
and has left it on record. ‘Although,’ he says, ‘the rotation of the
Earth is now established with all the certainty which the physical
sciences require, still a direct proof of that phenomenon ought to
interest both geometricians and astronomers.’ No man ever knew the
laws of the planetary motions better than Laplace, and before penning
such a sentence, it is probable that he had turned the subject in his
mind, and without discovering any process by which the object could be
attained; but it does not follow that if he had applied the whole force
of his genius to the task, he would not have succeeded. Be this as it
may, here we have the problem solved by a man not probably possessing
a tithe of his science or talent; and, what is very remarkable, after
the discovery was made, it was found to be legitimately deducible
from mathematical principles. * * * In this, as in many other cases,
the _fact_ comes first, and takes us by surprise; after which we find
that we had long been in possession of the principles from which it
flowed, and that, with the clue we had in our hands, theory should
have revealed the fact to us long before. M. Foucault’s communication
describing his experiments is in the _Comptes Rendus_ of the Academy
of Sciences, for 3rd February, 1851. His first experiments were made
with a pendulum only two metres (6ft. 6¹⁄₄in.) in length, consisting
of a steel wire from ⁶⁄₁₀ths to ¹¹⁄₁₀ths of a millimetre in diameter
(the millimetre is the 25th part of an inch); to the lower end of
which was attached a polished brass ball, weighing 5 kilogrammes, or
11 English pounds. * * * A metallic point projecting below the ball,
and so directed as if it formed a continuation of the suspension wire,
served as an index to mark the change of position more precisely. The
pendulum hung from a steel plate in such a manner as to move freely in
any vertical plane. To start the oscillatory movement without giving
the ball any bias, it was drawn to one side with a cord, which held
the ball by a loop; the cord was then burned, after which the loop
fell off, and the vibrations (generally limited to an arc of 15 or 20
degrees) commenced. In one minute the ball had sensibly deviated from
the original plane of vibration towards the observer’s left. Afterwards
he experimented at the Observatory with a pendulum 11 metres (30 feet)
long, and latterly at the Pantheon with one still longer. The advantage
of a large pendulum, as compared with a small one, is, that a longer
time elapses before it comes to a state of rest; for machinery cannot
be employed here, as in a clock, to continue the motion. The pendulum
is suspended over the centre of a circular table, whose circumference
is divided into degrees and minutes. The vibrations are begun in the
manner above described, and in a short time it is observed that the
pendulum, instead of returning to the same point of the circle from
which it started, has shifted to the left. If narrowly observed, the
change in the plane of vibration (says M. Foucault) is perceptible
in one minute, and in half an hour, “Il saute aux yeux,” it is quite
palpable. At Paris the change exceeds 11 degrees in an hour. Thus,
supposing the oscillations to commence in a plane directed south and
north, in two hours the oscillations will point SSW. and NNE.; in four
hours they will point SW. and NE.; and in eight hours the oscillations
will point due east and west, or at right angles to their original
direction. To a spectator the change seems to be in the pendulum,
which, without any visible cause, has shifted round a quarter of a
circle; but the real change is in the table, which, resting on the
Earth, and accompanying it in its rotation, has performed a fourth (and
something more) of its diurnal revolution.
No one anticipated such a result; and the experiment has been received
by some with incredulity, by all with wonderment; and one source of the
incredulity arises from the difficulty of conceiving how, amidst the
ten thousand experiments of which the pendulum has been the subject, so
remarkable a fact could have escaped notice so long. Fully admitting
that these experiments have generally been conducted with pendulums
which had little freedom of motion horizontally, we still think odd
that somebody did not stumble upon the curious fact.
Though all the parts of the Earth complete their revolution in the
same space of time, it is found that the rate of horizontal motion
in Foucault’s pendulum varies with the latitude of the place where
the experiment is made. At the pole, the pendulum would pass over 15
degrees in an hour, like the Earth itself, and complete its circuit in
24 hours. At Edinburgh, the pendulum would pass over 12¹⁄₂ degrees in
an hour, and would complete its revolution in 29 hours 7 minutes. At
Paris, the rate of motion is 11 degrees and 20 minutes per hour, and
the revolution should be completed in 32 hours.
[Illustration: FIG. 31.]
Let the above figure represent a portion of the Earth’s surface near
the north pole N. Suppose the pendulum to be set in motion at _m_, so
as to vibrate in the direction _x y_, which coincides with that of the
meridian _m_ N or _m r_. The Earth in the meantime is pursuing its
easterly course, and the meridian line _m_ N has come in six hours into
the position _n_ N. It has been hitherto supposed that the pendulum
would now vibrate in the new direction _n_ N, assumed by the meridian,
but thanks to M. Foucault, we now know that this is a mistake. The
pendulum will vibrate in a plane _x n y_, parallel to its original
plane at _m_, as will be manifest if the plane of vibration points to
some object in absolute space, such as a star. While the meridian line
_m_ N will in the course of 24 hours range round the whole circle of
the heavens, and point successively in the direction _n_ N, _o_ N, _p_
N, _r_ N, _s_ N, _t_ N, and _u_ N, the pendulum’s plane of vibration
_x y_, whether at _m_, at _n_, at _o_, at _p_, at _r_, at _s_, at _t_,
or at _u_, will always be parallel to itself, pointing invariably to
the same star, and were a circular table placed under the pendulum, its
plane of vibration, while really stationary, would appear to perform a
complete revolution.
This stationary position of the plane of vibration at the pole seems
to present little difficulty. We impress a peculiar motion on the
pendulum in setting it a going. The Earth is at the same time carrying
the pendulum eastward, but _at the pole_ the one motion will not
interfere with the other. The only action of the Earth on the pendulum
there is that of attracting it towards its own (the Earth’s) centre.
But this attraction is exactly in the plane of vibration and merely
tends to continue the oscillatory motion without disturbing it. It
is otherwise if the experiment is made at some other point, say 20
degrees distant from the pole. Supposing the vibrations to commence in
the plane of the meridian, then as the tendency of the pendulum is to
continue its vibrations in planes absolutely parallel to the original
plane, it will be seen, if we trace both motions, that, while it is
carried eastward with the Earth along a parallel of latitude, this
tendency will operate to draw the plane of vibration away from a ‘great
circle’ into a ‘small circle’ (that is, from a circle dividing the
globe into two _equal_ parts, into one dividing it into two _unequal_
parts). But the pendulum _must_ necessarily move in a ‘great circle,’
and hence to counteract its tendency to deviate into a ‘small circle,’
a correctory movement is constantly going on, to which the lengthening
of the period necessary to complete a revolution must be ascribed. At
Edinburgh the period is about 29 hours, at Paris 32, at Cairo 48, at
Calcutta 63. At the Equator, the period stretches out to infinity. M.
Foucault’s rule is, that the angular space passed over by the pendulum
at any latitude in a given time, is equal to the angular motion of
the Earth in the period, multiplied by the sine of the latitude.
The angular motion of the Earth is 15 degrees per hour; and at the
latitude of 30, for example, the sine being to radius as 500 to 1000,
the angular motion of the pendulum will consequently be 7¹⁄₂ degrees per
hour. It is, therefore, easily found. It follows that the motions of
the pendulum may be employed in a rough way to indicate the latitude of
a place.”[37]
[37] Supplement of the _Manchester Examiner_, of May 24, 1851.
Notwithstanding the apparent certainty of these pendulum experiments,
and the supposed exactitude of the conclusions deducible therefrom,
many of the same school of philosophy differed with each other,
remained dissatisfied, and raised very serious objections both to the
value of the experiments themselves, and to the supposed proof which
they furnished of the Earth’s rotation. One writer in the _Times_
newspaper of the period, who signs himself “B. A. C.,” says, “I have
read the accounts of the Parisian experiment as they have appeared in
many of our papers, and must confess that I still remain unconvinced
of the reality of the phenomenon. It appears to me that, except at
the pole where the point of suspension is immovable, no result can
be obtained. In other cases the shifting of the direction of passage
through the lowest point that takes place during an excursion of
the pendulum, from that point in one direction and its return to it
again, will be exactly compensated by the corresponding shifting in
the contrary direction during the pendulum’s excursion on the opposite
side. Take a particular case. Suppose the pendulum in any latitude to
be set oscillating in the meridian plane, and to be started from the
vertical towards the south. It is obvious that the wire by which it
is suspended _does not continue to describe a plane_, but a species
of conoidal surface; that when the pendulum has reached its extreme
point its direction is to the south-west, and that as the tangent plane
to the described surface through the point of suspension necessarily
contains the normal to the Earth at the same point, the pendulum on
its return passes through the same point in the direction north-east.
Now, starting again from this point, we have exactly the circumstances
of the last case, the primary plane being shifted slightly out of the
meridian; when, therefore, the pendulum has reached its extreme point
of excursion the direction of the wire is to the west of this plane,
and when it returns to the vertical the direction of passage through
the lowest point is as much to the west of this plane as it was in the
former case to the west of the meridian plane; but since it is now
moving from north to south instead of from south to north, as in the
former case, its former deviation receives complete compensation, and
the primary plane returns again to the meridian, when the whole process
recurs.”
In the _Liverpool Mercury_ of May 23, 1851, the following letter
appeared:--“The supposed manifestation of the Rotation of the
Earth.--The French, English, and European continental journals have
given publicity to an experiment made in Paris with a pendulum; which
experiment is said to have had the same results when made elsewhere.
To the facts set forth no contradiction has been given, and it is
therefore to be hoped that they are true. The correctness of the
inferences drawn from the facts is another matter. The first position
of these theorists is, that in a complete vacuum beyond the sphere of
the Earth’s atmosphere, a pendulum will continue to oscillate in one
and the same original plane. On that supposition their whole theory is
founded. In making this supposition the fact is overlooked that there
_is no vibratory motion_ unless through atmospheric resistance, or by
force opposing impulse. Perpetual progress in rectilinear motion may be
imagined, as in the corpuscular theory of light; circular motion may
also be found in the planetary systems; and parabolic and hyperbolic
motions in those of comets; but vibration is artificial and of limited
duration. No body in nature returns the same road it went, unless
artificially constrained to do so. The supposition of a permanent
vibratory motion such as is presumed in the theory advanced, is
_unfounded in fact_, and absurd in idea; and the whole affair of this
proclaimed discovery falls to the ground. It is what the French call a
‘mystification’--anglice a ‘humbug.’ Liverpool, 22nd May, 1851.”
“T.”
Another writer declared that he and others had made many experiments
and had discovered that the plane of vibration had nothing whatever
to do with the meridian longitude nor with the Earth’s motion, but
followed the plane of the magnetic meridian.
“A scientific gentleman in Dundee recently tried the pendulum
experiment, and he says--‘that the pendulum is capable of showing the
Earth’s motion I regard as a _gross delusion_; but that it tends to the
_magnetic meridian_ I have found to be a fact.’”[38]
[38] _Liverpool Journal_, May 17, 1851.
In many cases the experiments have not shown a change at all in the
plane of oscillation of the pendulum; in others the alteration in
the plane of vibration has been in the _wrong direction_; and very
often the _rate of variation_ has been altogether different to that
which theory indicated. The following is a case in illustration:--“On
Wednesday evening the Rev. H. H. Jones, F.R.A.S., exhibited the
apparatus of Foucault to illustrate the diurnal rotation of the Earth,
in the Library Hall of the Manchester Athenæum. The preparations
were simple. A circle of chalk was drawn in the centre of the floor,
immediately under the arched skylight. The circle was exactly 360
inches in its circumference, every inch being intended to represent
one degree. According to a calculation Mr. Jones had made, and which
he produced at the Philosophical Society six weeks ago, the plane of
oscillation of the pendulum would, at Manchester, diverge about one
degree in five minutes, or perhaps a very little less. He therefore
drew this circle exactly 360 inches round, and marked the inches on
its circumference. The pendulum was hung from the skylight immediately
over the centre of the circle, the point of suspension being 25 feet
high. At that length of wire, it should require 2¹⁄₂ seconds to make
each oscillation across the circle. The brazen ball, which at the end
of a fine wire constituted the pendulum, was furnished with a point,
to enable the spectator to observe the more easily its course. A long
line was drawn through the diameter of the circle, due north and south,
and the pendulum started so as to swing exactly along this line; to the
westward of which, at intervals of three inches at the circumference,
two other lines were drawn, passing through the centre. According
to the theory, the pendulum should diverge from its original line
towards the west, at the rate of one inch or degree in five minutes.
This, however, Mr. Jones explained, was a perfection of accuracy only
attainable in a vacuum, and rarely could be approached where the
pendulum had to pass through an atmosphere subject to disturbances;
besides, it was difficult to avoid giving it some slight lateral bias
at starting. In order to obviate this as much as possible, the steel
wire was as fine as would bear the weight, ¹⁄₃₀th of an inch thick;
and the point of suspension was adjusted with delicate nicety. An iron
bolt was screwed into the frame-work of the skylight; into it a brass
nut was inserted--the wire passed through the nut (the hollow sides
of which were bell-shaped, in order to give it fair play), and at the
top the wire ended in a globular piece, there being also a fine screw
to keep it from slipping. * * * The pendulum was gently drawn up to
one side, at the southern end of the diametrical line, and attached
by a thread to something near. When it hung quite still the thread was
burnt asunder, and the pendulum began to oscillate to and fro across
the circle. * * * Before it had been going on quite seven minutes,
it had reached nearly the third degree towards the west, whereas it
_ought_ to have occupied a quarter of an hour in getting thus far from
its starting line, even making no allowance for the resistance of the
atmosphere.”[39]
[39] “Manchester Examiner” (Supplement), May 24, 1851.
Besides the irregularities so often observed in the time and direction
of the pendulum vibrations, and which are quite sufficient to render
them worthless as evidence of the Earth’s motion, the use which
the Newtonian astronomers made of the general fact that the plane
of oscillation is variable, was most unfair and illogical. It was
proclaimed to the world as a visible proof of the Earth’s diurnal
motion; but the motion was _assumed to exist_, and then employed to
explain the cause of the fact which was first called a proof of the
thing assumed! A greater violation of the laws of investigation was
never perpetrated! The whole subject as developed and applied by the
theoretical philosophers is to the fullest degree unreasonable and
absurd--not a “jot or tittle” better than the reasoning contained
in the following letter:--“Sir,--Allow me to call your serious and
polite attention to the extraordinary phenomenon, demonstrating the
rotation of the Earth, which I at this present moment experience, and
you yourself or anybody else, I have not the slightest doubt, would
be satisfied of, under similar circumstances. Some sceptical and
obstinate individuals may doubt that the Earth’s motion is visible,
but I say from personal observation its a positive fact. I don’t
care about latitude or longitude, or a vibratory pendulum revolving
round the sine of a tangent on a spherical surface, nor axes, nor
apsides, nor anything of the sort. That is all rubbish. All I know
is, I see the ceiling of this coffee-room going round. I perceive
this distinctly with the naked eye--only my sight has been sharpened
by a slight stimulant. I write after my sixth go of brandy-and-water,
whereof witness my hand,”--“Swiggins”--_Goose and Gridiron, May 5,
1851._--“P.S. Why do two waiters come when I only call one?”[40]
[40] “Punch,” May 10, 1851.
The whole matter as handled by the astronomical theorists is fully
deserving of the ridicule implied in the above quotation from _Punch_;
but because great ingenuity has been shewn, and much thought and
devotion manifested in connection with it, and the general public
thereby greatly deceived, it is necessary that the subject should be
fairly and seriously examined. What are the facts?
First.--When a pendulum, constructed according to the plan of M.
Foucault, is allowed to vibrate, its plane of vibration is often
variable--_not always_. The variation when it _does_ occur, is _not
uniform_--is not always the same in the same place; nor always the
same either in its rate or velocity, or in its direction. It cannot
therefore be taken as evidence; for that which is inconstant cannot be
used in favour of or against any given proposition. It therefore _is
not evidence and proves nothing_!
Secondly.--If the plane of vibration _is_ observed to change, where
is the connection between such change and the supposed motion of the
Earth? What principle of reasoning guides the experimenter to the
conclusion that it is the Earth which moves underneath the pendulum,
and not the pendulum which moves over the Earth? What logical right or
necessity forces one conclusion in preference to the other?