Part 7

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.”