Part 2 (2/2)
[Footnote 1: The _Via Lactea_, or ”Milky Way,” had long been supposed to consist of a nebulous, vague, luminous matter, but Herschel showed that it was really made up of stars and systems of stars.]
After struggling for some thirty minutes against his rapidly increasing weakness, the great astronomer, bowed by his burden of years and labours, was forced to retire to his bed, with little hope that he would ever rise from it again. For ten days and nights his wife and sister watched by his side in painful suspense, until, on the 25th of August, the end came. Peacefully closed a life which had pa.s.sed in a peace and quietness not often vouchsafed to man.
Herschel, says a brother astronomer, will never cease to occupy an eminent place in the small group of our contemporary men of genius, while his name will descend to the most distant posterity. The variety and the magnificence of his labours vie with their extent. The more they are studied, the more they are admired. For it is with great men as it is with great movements in the Arts and in national history,--we cannot understand them without observing them from different points of view.
What a brilliant roll of achievements is recalled to the mind by the name of William Herschel! The discovery of Ura.n.u.s, and of its satellites; of the fifth and sixth satellites of Saturn; of the many spots at the poles of Mars; of the rotation of Saturn's ring; of the belts of Saturn; of the rotation of Jupiter's satellites; of the daily period of Saturn and Venus; and of the motions of binary sidereal systems,--added to his investigations into nebulae, the Milky Way, and double, triple, and multiple stars;--all this we owe to his patient, his persevering, his daring genius! He may almost be styled the Father of Modern Astronomy.
CHAPTER IV.
We 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 ill.u.s.trious 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 pa.s.sed 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 ent.i.tled, ”A Collection of Examples of the Application of the Calculus to Finite Differences.” To our young readers such a t.i.tle will convey no meaning; and we refer to it here only to ill.u.s.trate 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 a.n.a.lyzation, that intelligence and scrupulousness in collecting facts, and that boldness in deducing new inferences from them, which were characteristic of his ill.u.s.trious 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 a.s.siduous 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 circ.u.mstances 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, a.s.sembled 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 cl.u.s.ters 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-cl.u.s.ters, 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----[1] and the children are, thank G.o.d, 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 pa.s.sage. 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 lat.i.tudes;' that is to say, to the s.p.a.ce about five or six degrees broad near the equator, where the trade-winds cease, and where it is no unusual thing for a s.h.i.+p 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 uns.h.i.+p 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 s.h.i.+p, 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.
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