CHAPTER IV.
e now propose to furnish a brief sketch of the life of Sir John Frederick William Herschel, the only son of Sir William, and not less illustrious as a man of science.
He was born at Slough, in the year 1792. Evincing considerable talents at a very early age, he received a careful private education under Mr. Rogers, a Scottish mathematician of distinguished merit; and afterwards was sent to St. John's College, Cambridge, always famous as a nursery of mathematical and scientific prodigies! Here he pursued his studies with remarkable success, suffering no obstacles to daunt him, and wasting no opportunities of improvement. His fellow-collegians regarded him as one who would add to the high repute of the college, and rejoiced at the brilliant ease with which he passed every examination. In 1813 he took his degree of B.A., and consummated a long series of successes by becoming "senior wrangler," and "Smith's prizeman;" these being the two highest distinctions to which a Cambridge scholar can attain.
In the same year, when he was hardly twenty-one, he published a work entitled, "A Collection of Examples of the Application of the Calculus to Finite Differences." To our young readers such a title will convey no meaning; and we refer to it here only to illustrate the industry and careful thought of the young student, which had rendered possible such a result.
Returning to Slough, he continued his studies in mathematics, chemistry, and natural philosophy, and in various publications exhibited that faculty of observation and analyzation, that intelligence and scrupulousness in collecting facts, and that boldness in deducing new inferences from them, which were characteristic of his illustrious father. The subjects he took up were so abstruse, that we could not hope to make our readers understand what he accomplished, or how far he excelled his predecessors in his grasp and comprehension of them. For instance: if we tell them that in 1820 he wrote a paper "On the Theory and Summation of Series;" communicated to the Cambridge Philosophical Society his discovery that the two kinds of rotatory polarization in rock crystal were related to the plagihedral faces of that mineral; and issued an able treatise "On Certain Remarkable Instances of Deviation from Newton's Tints in the Polarized Tints of Uniaxal Crystals,"—they will gain no very distinct idea of the significance or value of these researches. Again: it will not be very intelligible to them to be informed that, in 1822, he communicated to the Royal Society of Edinburgh a paper "On the Absorption of Light by Coloured Media", in which he enunciated a new method of measuring the dispersion of transparent bodies by stopping the green, yellow, and most refrangible red rays, and thus rendering visible the rays situated rigorously at the end of the spectrum. But they will understand that these results could have been attained only by the most assiduous industry and the most unflinching perseverance. And it is on account of this industry and this perseverance that we recommend Herschel as an example to our readers. They may not make the same progress in science, or achieve the same reputation. It is not necessary they should. Humble work is not less honourable, if it be done conscientiously, and with a sincere desire to do the best that it is in our power to do.
An interesting feature in the younger Herschel's character was his loving care for his father's fame. He was ever most anxious that the full measure of his services to science should be recognized and appreciated. Thus, in 1823, he writes to his aunt:—
"I have been long threatening to send you a long letter, but have always been prevented by circumstances and want of leisure from executing my intention. The truth is, I have been so much occupied with astronomy of late, that I have had little time for anything else—the reduction of those double stars, and the necessity it has put me under of looking over the journals, reviews, &c, for information on what has already been done, and in many cases of re-casting up my father's measures, swallows up a great deal of time and labour. But I have the satisfaction of being able to state that our results in most instances confirm and establish my father's views in a remarkable manner. These inquiries have taken me off the republication of his printed papers for the present.
"I think I shall be adding more to his fame by pursuing and verifying his observations than by reprinting them. But I have by no means abandoned the idea. Meanwhile, I am not sorry to hear they are about to be translated into German.... I hope this season to commence a series of observations with the twenty-foot reflector, which is now in fine order. The forty-foot is no longer capable of being used, but I shall suffer it to stand as a monument."
In reference to this famous telescope, we may digress to state that its remains have been carefully preserved.
The metal tube of the instrument, carrying at one end the recently cleaned mirror of four feet ten inches in diameter, has been placed horizontally in the meridian line, on solid piles of masonry, in the midst of the circle where the apparatus used in manoeuvring it was formerly placed. On the 1st of January 1840, Sir John Herschel, his wife, their seven children, and some old family servants, assembled at Slough. Exactly at noon the party walked several times in procession round the instrument; they then entered the gigantic tube, seated themselves on benches previously prepared, and chanted a requiem with English words composed by Sir John Herschel himself. Then issuing from the tube, they ranged themselves around it, while its opening was hermetically sealed.
In March 1821, the younger Herschel, in conjunction with Sir James South, undertook a series of observations on the distances and positions of three hundred and eighty double and triple stars, by means of two splendid achromatic telescopes of five and seven focal length. These were continued during 1822 and 1823, and have proved of great service to astronomers.
Having pursued with much zeal the study of optics, and experimented largely and carefully on the double refraction and polarization of light, he compiled a treatise on the subject for the "Encyclopaedia Metropolitana" It has been translated into French by M. Quetelet; and both foreign and English men of science have been accustomed to regard it as indicating a new point of departure in the important branch of science to which it is devoted.
Astronomy, however, became for him, as for his father, the great pursuit of his laborious life; and having constructed telescopes of singular magnitude and power, he entered upon a study of the Sidereal World. In 1825 he commenced a careful re-examination of the numerous nebulae and starry clusters which had been discovered by his father, and described in the "Philosophical Transactions," fixing their positions and investigating their aspects. He devoted eight years to this magnum opus, completing it in 1832. The catalogue which he then contributed to the "Philosophical Transactions" includes 2306 nebulae and star-clusters, of which 525 were discovered by himself. While engaged in this difficult task, Herschel discovered between three and four thousand double stars, which he described in the Memoirs of the Astronomical Society. His observations were made with an excellent Newtonian telescope, twenty feet in focal length, and eighteen and a half inches in aperture; and having obtained, to use his own expression, "a sufficient mastery over the instrument," the idea occurred to him of making it available for a survey of the southern heavens. Accordingly, he left England on the 13th of November 1833, and arrived at Cape Town on the 16th of January 1834. Five days later he wrote to his aunt as follows:—
"Here we are safely lauded and comfortably housed at the far end of Africa; and having secured the landing and final storage of all the telescopes and other matters, as far as I can see, without the slightest injury, I lose no time in reporting to you our good success so far. M——[5] and the children are, thank God, quite well; though, for fear you should think her too good a sailor, I ought to add that she continued sea-sick, at intervals, during the whole passage. We were nine weeks and two days at sea, during which period we experienced only one day of contrary wind. We had a brisk breeze 'right aft' all the way from the Bay of Biscay (which we never entered) to the 'calm latitudes;' that is to say, to the space about five or six degrees broad near the equator, where the trade-winds cease, and where it is no unusual thing for a ship to lie becalmed for a month or six weeks, frying under a vertical sun. Such, however, was not our fate. We were detained only three or four days by the calms usual in that zone, but never quite still, or driven out of our course; and immediately on crossing 'the line' got a good breeze (the south-east trade-wind), which carried us round Trinidad; then exchanged it for a north-west wind, which, with the exception of one day's squall from the south-east, carried us straight into Table Bay. On the night of the 14th we were told to prepare to see the Table Mountain. Next morning (N.B., we had not seen land before since leaving England), at dawn, the welcome word land' was heard; and there stood this magnificent hill, with all its attendant mountain-range down to the farthest point of South Africa, full in view, with a clear blue ghost-like outline; and that night we cast anchor within the Bay. Next morning early we landed, under escort of Dr. Stewart, M——'s brother, and you may imagine the meeting. We took up our quarters at a most comfortable lodging-house (Miss Robe's), and I proceeded, without loss of time, to unship the instruments. This was no trifling operation, as they filled (with the rest of our luggage) fifteen large boats; and, owing to the difficulty of getting them up from the hold of the ship, required several days to complete the landing. During the whole time (and indeed up to this moment) not a single south-east gale, the summer torment of this harbour, has occurred. This is a thing almost unheard of here, and has indeed been most fortunate, since otherwise it is not at all unlikely that some of the boats, laden as they were to the water's edge, might have been lost, and the whole business crippled.
"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 astonishing brilliancy of the constellations, which the calm, clear nights show off to great advantage."
Herschel married a Miss Stewart in February 1826.
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 entitled "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 illustrious 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 noble 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 entitled "Outlines of Astronomy." In 1845, he was appointed President of the British Association; and in 1848, of the Royal Astronomical Society. To his other honours was added that of Chevalier of the Prussian order, "Pour la Mérite," 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 institutions 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 mass 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 mass 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 God's Wall.
With a similar fertility of illustration, 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 cluster 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 surpassed by the sudden opening of a chasm which vomited forth fire, and red-hot stones and ashes, until they accumulated in a range of six large mountain masses,—one of which, now known as the volcano of Jorullo, attains an altitude 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 quantity 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 mass; just as, when a ship 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 God's Wall, in Cutch.
Volcanic eruptions are easily explicable on this principle,—the volcano being simply a vent for the passage 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 accumulation 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 quantity 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 unassumingness 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.