Part 3 (1/2)
[Footnote 1: Herschel married a Miss Stewart in February 1826.]
”For the last two or three days we have been looking at houses, and have all but agreed for one--a most beautiful place within four or five miles out of town, called 'The Grove.' In point of situation it is a perfect paradise, in rich and magnificent mountain-scenery, and sheltered from all winds, even the fierce south-easter, by thick surrounding woods. I must reserve for my next all description of the gorgeous display of flowers which adorns this splendid country, as well as of the astonis.h.i.+ng brilliancy of the constellations, which the calm, clear nights show off to great advantage.”
Mr. Herschel settled at Feldhausen, about 142 feet above the sea, and in long. 22 46' 9”.11 E., and lat. 33 58' 26”.59 S. Here he entered upon his great series of observations of the southern heavens, which he continued with unwearied ardour for a period of four years. The results were afterwards published, at the cost of the Duke of Northumberland, in a work ent.i.tled ”Results of Astronomical Observations made in 1834-35-36-37-38, at the Cape of Good Hope.” In this superb work, which placed its author on an equality with the most brilliant and ill.u.s.trious astronomers, he defined and described 4015 of the nebulae and star-groups in the southern hemisphere, and 2995 of the double stars; besides entering into a variety of valuable particulars relative to Halley's comet, the solar spots, the satellites of Saturn, and the measurement of the apparent magnitude of stars.
On his return to England (in 1838) the astronomer received a n.o.ble welcome. Honours poured in upon him. The Gold Medal of the Astronomical Society was conferred upon him for a second time. William IV. had previously distinguished him with the Hanoverian order of K.H.; but, on the coronation of Queen Victoria, he received a baronetcy; and in 1839 the University of Oxford made him a D.C.L.
Continuing his career of scientific industry, he issued, in 1849, his important and very valuable treatise ent.i.tled ”Outlines of Astronomy.”
In 1845, he was appointed President of the British a.s.sociation; and in 1848, of the Royal Astronomical Society. To his other honours was added that of Chevalier of the Prussian order, ”Pour la Merite,” founded by Frederick the Great, and bestowed at all times with a discrimination which renders it a deeply-coveted distinction. Of the academies and leading scientific inst.i.tutions of the Continent and the United States, he was also an honorary or corresponding member.
Besides his works on meteorology and physical geography, he published, in 1867, an admirable little volume--”Familiar Lectures on Scientific Subjects.” In this he showed that he could write with as much ease and intelligibility for the general public as for the higher order of scientific inquirers. His style in this valuable manual of information has a charm of its own, and entices the reader into the consideration of subjects apparently abstruse. He is earned on from page to page without any great mental effort, and finds himself rapidly mastering difficulties which he had been accustomed to regard as insuperable.
Let us take the first lecture on ”Volcanoes and Earthquakes,” and obtain a glimpse of Herschel's mode of treatment. He refers to the greater and more permanent agencies which affect the configuration of our planet.
Everywhere, he says, and along every coast-line, we see the sea warring against the land, and overcoming it; wearing it and eating it down, and battering it to pieces; grinding those pieces to powder; carrying that powder away, and spreading it out over its own bottom, by the continued effect of the tides and currents. What a scene of continual activity is presented by the chalk-cliffs of Old England! How they are worn, and broken up, and fantastically sculptured by the influence of winds and waters! Precipices cut down to the sea-beach, constantly hammered by the waves, and constantly crumbling; the beach itself made of the flints outstanding after the softer chalk has been ground down and washed away; themselves grinding one another under the same ceaseless discipline--first rounded into pebbles, then worn into sand, and then carried further and further down the slope, to be replaced by fresh ones from the same source. Here the likeness of an old Gothic cathedral, with lofty arch, and shapely pinnacle; there the similitude of a ma.s.s of medieval fortifications, with crumbling battlements and shattered towers!
The same thing, the same waste and wear, is going on everywhere, round every coast. The rivers contribute their share to the great work of change. Look at the sand-banks at the mouth of the Thames. What are they, says Sir John Herschel, but the materials of our island carried out to sea by the stream? The Ganges carries away from the soil of India, and delivers into the sea, twice as much solid substance weekly as is contained in the Great Pyramid of Egypt. The Irawaddy sweeps off from Burmah sixty-two cubic feet of earth in every second of time, on an average Sometimes vast amount of earthy materials is transferred from one locality to another by river agency, as is the case in the deltas of the Nile and the Mississippi.
These changes operate silently, continuously, and unperceived by the ordinary observer; but Nature does not limit herself always and everywhere to such peaceful agencies. At times, and in certain places, she acts with startling abruptness and extraordinary violence. Let the volcano and the earthquake attest the immensity of her power. Let the earthquake tell how, within the memory of man, the whole coast-line of Chili, for 100 miles about Valparaiso, with the mighty chain of the Andes, was hoisted at one blow, and in a single night (November 19, 1822), from two to seven feet above its former level, leaving the beach below the old low-water mark high and dry. One of the Andean peaks upheaved on this occasion was the colossal ma.s.s of Aconcagua, which overlooks Valparaiso, and measures nearly 24,000 feet in height. On the same occasion, at least 10,000 square miles of country were estimated as having been upheaved; and the upheaval was not confined to the land, but extended far away to sea,--which was proved by the soundings off Valparaiso and along the coast having been found considerably shallower than they were before the shock.
In the year 1819, in an earthquake in India, in the district of Cutch, bordering on the Indus, a tract of country more than fifty miles long and sixteen miles broad was suddenly raised _ten feet_ above its former level. The raised portion still stands up above the unraised, like a long perpendicular rampart, known by the name of Ullah Bund, or G.o.d's Wall.
With a similar fertility of ill.u.s.tration, Herschel sets before us the phenomena of volcanic eruptions and their extraordinary effects.
In a district of Mexico, between the two streams of the Cintimba and the San Pedro, on the 28th of September 1789, a whole tract of ground, from three to four miles in extent, surged up like a foam-bubble, or the swell of a wave, to a height of upwards of 500 feet. Flames, lurid and crackling, broke forth over a surface of more than half a square league; and the earth, as if softened by heat, was seen to rise and sink like the rolling tide. Vast chasms opened in the earth, into which the two rivers poured their waters headlong; reappearing afterwards at no great distance from a cl.u.s.ter of _hornitos_, or small volcanic cones, which sprang out of the mighty mud-torrent that gradually covered the entire plain. Wonderful and awful as were these phenomena, they were surpa.s.sed by the sudden opening of a chasm which vomited forth fire, and red-hot stones and ashes, until they acc.u.mulated in a range of six large mountain ma.s.ses,--one of which, now known as the volcano of Jorullo, attains an alt.i.tude of 1690 feet above the ancient level.
In like manner Sir John proceeds to describe an eruption of Mount Tomboro, in the island of Sumbawa, the influence of which was felt to a distance of 1000 miles from its centre, in strange tremulous motions of the earth, and in the clash and clang of loud explosions. He says that he had seen it computed that the quant.i.ty of ashes and lava ejected in the course of this tremendous eruption would have formed three mountains of the size of Mont Blanc.
As to the nature of the forces which operate to produce this astounding result, Herschel puts forward a theory of singular simplicity and directness.
”The origin,” he says, ”of such an enormous power thus occasionally exerting itself, will no doubt seem very marvellous--little short, indeed, of miraculous intervention; but the mystery, after all, is not quite so great as at first it seems. We are permitted to look a little way into these great secrets of Nature; not far enough, indeed, to clear up every difficulty, but quite enough to penetrate us with admiration of that wonderful system of counterbalances and compensations, that adjustment of causes and consequences, by which, throughout all nature, evils are made to work their own cure, life to spring out of death, and renovation to tread in the steps and efface the vestiges of decay.” And he finds the clew to the secret, the key of the whole matter, in the earth's vast central heat. This it is which produces the convulsions that change the terrestrial configuration, and fill the minds of men with fear and awe. Conceive of ”a sea of fire, on which we are all floating, land and sea,”--a boiling, seething, incandescent reservoir in the centre of our planet; and the solution of the problem will seem to you not difficult. Such a sea would necessarily roll its liquid matter to and fro; and the removal of ever so small a portion from one point to another on the earth's surface would tend to disturb the equilibrium of the floating ma.s.s; just as, when a s.h.i.+p is launched into the river, the water it displaces is carried to the opposite bank with greater or less violence, according to the amount of displacement.
It is impossible, adds Herschel, but that this increase of pressure in some places and relief in others must be very unequal in their bearings.
So that at some point or another our planet's floating crust must be brought into a state of strain, and if there be a weak or a soft part a crack will at last take place. This is exactly what happened in the earthquake which originated the Allah Bund, or G.o.d's Wall, in Cutch.
Volcanic eruptions are easily explicable on this principle,--the volcano being simply a vent for the pa.s.sage of heated and molten matter, which the elevating pressure of the liquid below tends to eject. It is a well-known fact that volcanoes and earthquake-centres are nearly all situated on the borders or in the immediate neighbourhood of seas and oceans; and the reason would seem to be, that at such positions the acc.u.mulation of transported matter would necessarily attain its maximum, to whatever cause it might be due. Then again, as Herschel points out, the eruption of scorite and lava from the mouths of volcanoes, the result of the upward movement of the fiery liquid below, compensates in some degree for the downward transfer of material by detritus and alluvial deposits. Hence it may be inferred that, on the whole, the quant.i.ty of solid matter above the ocean-level probably remains nearly always at the same amount.
It is with this ease and lucidity that Sir John deals with scientific subjects of the greatest importance,--his genius resembling the elephant's trunk, which can balance a straw or rend an oak. In private life he displayed a simplicity of manner in harmony with the general una.s.sumingness of his character. In his books as in society, in society as in his books, he was the same,--that is, free from all ostentation, free from self-pride, free from the arrogance of superior knowledge, and as ready to unbend himself to a child as to discourse with men of science.
His career was a tranquil and a prosperous one, and, apart from the record of his discoveries and his honours, presents nothing of interest.
He was peculiarly happy in his domestic relations; and in the wide circle of friends attracted by the mingled charm of his intellect and manners. A devout Christian, a man of generosity and culture, a philosopher of great breadth of view and infinite patience of research,--we can place few better or brighter examples before our English youth than Sir John Herschel.
CHAPTER V.