CHAPTER III.
n August 1782 the Herschels removed to Datchet. Their new home was "a large neglected place; the house in a deplorably ruinous condition, the garden and grounds overgrown with weeds." Nor were the domestic arrangements more favourable. For a fortnight the little family were without a female servant; and an old woman, the gardener's wife, showed Miss Herschel the shops, where the high prices of every article, from coals to butcher's meat, appalled her. But of these inconveniences Herschel took no account. Enough for him that he was released from the drudgery of teaching, and free thenceforth to devote himself to the heavens and their wonders. A man whose thoughts are always with the stars can hardly be expected to trouble himself about the price of tallow-candles! Were there not capacious stables in which mirrors of any size could be ground; and a roomy laundry capable of easy conversion into a library, with one door opening on a large lawn, where the "small twenty-foot" was to take its stand? Compared with advantages such as these, what mattered the scarcity of "butcher's meat"? Herschel laughingly assured his sister that they could live on eggs and bacon; which, he confidently asserted, would cost next to nothing, now that they were really in the country!
And so he settled down to a life of quiet, industry at Datchet; his admirable sister being formally adopted as his assistant and secretary. Never had master a more devoted, a more enthusiastic, or a more intelligent servant! She shared in all his night-watches, with her eye constantly on the clock, and the pencil in her hand; with unerring accuracy she made all the complex calculations so frequently required; she made three or four copies of every observation in separate registers, co-ordinating, classifying, and analyzing them. If the scientific world, says Arago, saw with astonishment the unexampled rapidity with which Herschel's works succeeded one another for many years, they were greatly indebted for this affluence of production to the affectionate ardour of his sister Caroline. Her enthusiasm never failed; her industry knew no check; and her brother's fame was dearer to her than life.
In one of her letters she describes with graphic simplicity the "interior" at Datchet:—
"I found that I was to be trained for an assistant-astronomer; and by way of encouragement, a telescope adapted for 'sweeping' (or rapidly surveying a wide extent of space), consisting of a tube with two glasses, was given [to] me. I was to 'sweep for comets;' and I see by my journal that I began August 22nd, 1782, to write down and describe all remarkable appearances I saw in my 'sweeps.' But it was not till the last two months of the same year that I felt the least encouragement to spend the starlit nights on a grass-plot covered with dew or hoar-frost, without a human being near enough to be within call. I knew too little of the real heavens to be able to point out every object so as to find it again without losing too much time by consulting the Atlas. But all these troubles were removed when I knew my brother to be at no great distance, making observations with his various instruments on double stars, planets, and the like; and I could have his assistance immediately when I found a nebula, or cluster of stars, of which I intended to give a catalogue. I had the comfort to see," she continues, "that my brother was satisfied with my endeavours to assist him when he wanted another person either to run to the clocks, write down a memorandum, fetch and carry instruments, or measure the ground with poles,—of which something of the kind every moment would occur."
The conscientious care and assiduous industry with which Herschel made his measurements of the diameter of the Georgium Sidus (now called Uranus), and his interesting observations of other planets, of double stars with their coloured light, of cometary and nebulous appearances, were truly remarkable; as may be seen by the various papers which he wrote at this time for the Royal Society. In addition to all this labour, he perfected a twelve-inch speculum of vast magnifying power before the spring of 1784; and many hours were spent at the turning-bench, as not a night clear enough for observing ever passed without the devising of improvements in the mounting and motion of the various instruments then in use, or the test and trial of newly-constructed "eyepieces," most of which were executed by Herschel's own hands. "Wishing to save his time, he began to have some work of that kind done by a watchmaker, who had retired from business, and lived on Datchet Common; but the work was so bad, and the charges [were] so unreasonable, that he could not be employed. It was not till some time afterwards, in his frequent visits to the meetings of the Royal Society (made in moonlight nights), that he had an opportunity of looking about for mathematical workmen, opticians, and founders. But the work seldom answered expectation, and it was kept to be executed with improvements by Alexander during the few months he spent with us."
In July 1783 Herschel began his observations with his large twenty-foot telescope, though it was in an unfinished state; and his sister watched and waited with much apprehension when she knew him to be elevated some fifteen feet or more on a temporary crossbeam instead of a safe gallery. Here it is needful to explain, perhaps, that these huge astronomical telescopes are not used like ordinary glasses, to one end of which the observer applies his eye; the objects towards which the tube is directed being thrown upon a large mirror, which is attached to it externally at some distance from the ground. The observer, therefore, needs to be mounted on an elevated platform or gallery, from which he can conveniently inspect the mirror. One night, in a very high wind, Herschel had scarcely descended from his station before the whole apparatus came down; and his sister was in continual apprehension of some serious accident. One such, indeed, occurred, and to herself. The evening of the 31st of December had been cloudy, but as a few stars shone forth about ten o'clock, hurried preparations were made for observing. Herschel, standing at the front of the telescope, directed his sister to make a certain alteration in the lateral motion, which was done by machinery, on which the point of support of the tube and mirror rested. At each end of the machine or trough was an iron hook, such as butchers use for suspending their joints of meat; and having to run in the dark across ground covered a foot deep with melting snow, Miss Herschel fell on one of these hooks, which entered her right leg above the knee. To her brother's injunction, "Make haste!" she could answer only by a pitiful cry, "I am hooked!" He and the workmen hastened immediately to her assistance, but they could not disentangle her without leaving nearly two ounces of her flesh behind. For some weeks she was an invalid, and at one time it was feared that amputation might be necessary.
Not satisfied with the magnifying power of any of the instruments he had hitherto constructed, Herschel resolved, in 1784, to attempt a forty-foot telescope. Such a work, however, was far beyond his limited private resources; and he did not venture to undertake it until promised a royal bounty of £2000. Then he removed from Datchet to Clay Hall, Old Windsor; and again, in 1786, to Slough, where he finally settled, and succeeded in erecting a commodious and well-equipped observatory. "We may confidently assert," says Arago, "relative to the little house and garden of Slough, that it is the spot of all the world where the greatest number of discoveries have been made. The name of that village will never perish: science will transmit it religiously to our latest posterity."
At Slough, as at Datchet, prevailed the most enthusiastic industry; and the house was soon as full of well-ordered labour as a bee-hive. Smiths were kept constantly at work on different parts of the new telescopic leviathan; and a whole troop of labourers was engaged in grinding the tools required for shaping and polishing its mirror. Had not a cloudy or moonlight night sometimes intervened, Herschel and his sister must have died of sheer exhaustion, for they toiled with unremitting ardour both day and night. With the morning came the workpeople, of whom no fewer than between thirty and forty were at work for upwards of three months together: some employed in felling and rooting out trees, some digging and preparing the ground for the bricklayers, who were laying the foundation for the telescope. Then there were the carpenter and his men; and, meanwhile, the smith was converting a wash-house into a forge, and manufacturing complete sets of tools for his own share of the labour. In short, the place was at one time a complete workshop for the manufacture of optical instruments; and it was a pleasure to enter it for the purpose of observing the fervour of the great astronomer, and the reverent attention given to his orders.
It is impossible not to refer here to the sisterly devotion of Caroline Herschel, who was in every respect worthy of her noble-minded, tender-hearted, and enthusiastic brother.
She stood beside him to the last, sharing his labours, brightening his life. In the days, says her biographer, when Herschel gave up a lucrative career that he might dedicate all his energies to astronomical pursuits, it was through her care and thriftiness that he was spared from the unrest of pecuniary anxieties. As she had been his helper and assistant during his career as a popular musician, so she became his helper and assistant when he gave himself up, like the Chaldeans of old, to the study of the stars. By dint of a resolute will and a love that shrank from no sacrifice or exertion, she acquired such a knowledge of mathematics and calculations, mysterious as these generally seem to the feminine mind, that she was able to formulate with exactness the result of her brother's researches. She never failed to be his willing fellow-labourer in the workshop; she helped him to grind and polish his mirrors; she stood beside his telescope, in order to record his observations, during the dark and bitter mid-winter nights, when the very ink was frozen in the bottle. It may be said, without exaggeration, that she kept him alive by her care: thinking nothing of herself, she lived for him, and him alone. She loved him, she believed in him, she aided him with all her heart and all her strength. Her mental powers were very considerable; and undoubtedly she might have attained to eminence on her own account, for she herself discovered no fewer than eight comets. But she shunned self-glorification; she desired to live in her brother's shadow; she worked for him, never for herself; and in her elevated character no feature more strongly demands our admiration than her heroic though unconscious self-denial. Happy the man who has such a sister; happy the sister whose brother is worthy of so much devotion! It is pleasant to know that William Herschel deserved the love so lavishly poured out at his feet; that great as were his achievements in science, lofty and broad as was his genius, they were fully sustained and ennobled by the beauty and worth of his inner life. Who can contemplate their twofold career in all its singleness of purpose, its purity, its unselfishness, its sublime disregard of worldly pleasures, without emotion? The lessons told by such a life are worth all the moral treatises ever written.
To Miss Herschel's diary we again refer, for a glimpse of the occupations of her brother and herself at Slough in the first two years of their residence. These two years, to use an apt expression of her own, were spent in a perfect chaos of business. The garden and workrooms swarmed with labourers and workmen—smiths and carpenters speeding to and fro between the forge and the forty-foot machinery; and so incessant was the vigilance of Herschel, that not a screw-bolt in the whole apparatus was fixed except under his eye. "I have seen him," writes his sister, "lying stretched many an hour in the burning sun, across the top beam, whilst the iron-work for the various motions [of the great telescope] was being fixed." At one time no fewer than twenty-four men, in relays of twelve each, were engaged in grinding and polishing day and night; and Herschel never left them, taking his food without allowing himself time to sit down to table.
"In August 1787," writes the diarist, "an additional man-servant was engaged, who would be wanted at the handles of the motions of the forty-foot,"—that is, to raise or lower it, or move it from side to side, as might be required,—"for which the mirror in the beginning of July was so far finished as to be used for occasional observations on trial. Such a person was also necessary for showing the telescopes to the curious strangers, as by their numerous visits my brother and myself had for some time past been much incommoded. In consequence of an application made through Sir J. Banks to the king, my brother had in August a second sum of £2000 granted for completing the forty-foot, and £200 yearly for the expense of repairs; such as ropes, painting, &c., and the keep and clothing of the men who attended at night. A salary of £50 a year was also settled on me, as an assistant to my brother. A great uneasiness was by this means removed from my mind; for though I had generally (and especially during the last busy six years) been almost the keeper of my brother's purse, with a charge to provide for my personal wants, only annexing in my accounts the memorandum 'For Car.' to the sums so laid out. When cast up, they hardly amounted to seven or eight pounds per year since the time we had left Bath. Nothing but bankruptcy had all the while been running through my silly head, when looking at the sums of my weekly accounts, and knowing they could be but trifling in comparison with what had been and had yet to be paid in town. I will only add, that from this time the utmost activity prevailed to forward the completion of the forty-foot."
In recognition of his scientific triumphs, the honorary degree of LL.D was conferred upon Herschel, in 1786, by the University of Oxford. They were triumphs that well merited such a recognition. He had already made some important observations on the nature of double stars, on the dimensions of the telescopic planets, and had begun his famous investigations into the composition of the nebulae,—those clusters of stars and nebulous matter which had previously proved such a problem to astronomers. The remarkable phenomenon of a periodical change of intensity in certain stars, which wax and wane in radiance like a revolving light, had also excited his attention. Further, he had entered upon the experiments which ultimately showed that the Sun positively moves; that in this, as in other respects, the magnificent orb of day must be ranged among the stars; that the apparently inextricable irregularities of numerous sidereal proper motions arise in great part from the displacement of the Solar System; that, in short, the point of space toward which Earth and its sister planets are annually advancing, is situated in the constellation of Hercules.
"Let us," says a French writer, "to these immortal labours add the ingenious ideas that we owe to Herschel on the nebulae, on the constitution of the Milky Way, on the Universe as a whole,—ideas which almost by themselves constitute the actual history of the formation of the worlds,—and we cannot but have a deep reverence for that powerful genius that scarcely ever erred, notwithstanding the ardour of its imagination."
The ordinary spectator, looking upon the face of the heavens through a telescope, had, prior to Herschel's time, felt his curiosity excited by the appearance here and there of filmy patches, vague in structure and irregular in shape, which, from their resemblance to clouds, received the name of nebulae. What these were, no astronomer had succeeded in defining. It was left for Herschel, with his rare powers of patient and discriminating observation, assisted by the more powerful instruments which his ingenuity succeeded in constructing, to discern in them innumerable groups of worlds, in various stages of formation! A new light was thrown upon the history of the Universe. Man was able to assist, as it were, at the process of creation, and to watch the development of a mass of incoherent matter into a perfect star. This alone was a discovery which might well have immortalised the name of Herschel.
But we owe to him the elements of our knowledge of the Sun's physical constitution. He swept aside the erroneous theories and conjectures which had previously prevailed, and guided the astronomical inquirer into the right path. He convinced himself, by long and patient researches, that the luminous envelope of the great "orb of day" was neither a liquid nor an elastic fluid; that it was in certain respects analogous to the clouds which wreathe our mountain-summits and fertilize our plains; that it floated in the solar atmosphere. Thence he came to the conclusion that the Sun has two atmospheres, endowed with motions quite independent of each other. An elastic fluid, now known as the photosphere, is in course of continual formation on the dark rugged surface of the solar mass; and rising, on account of its specific lightness, it forms the pores in the stratum of reflecting clouds; then, combining with other gases, it produces the irregularities or furrows in the luminous cloud-region. When the ascending currents are powerful, they create those appearances which astronomers designate the nuclei, the penumbrae, the faculae.
Such was Herschel's explanation of the mode of formation of the solar spots; and allowing it to be well-founded, we must expect to find—what is, indeed, the case—that the Sun does not always and regularly pour forth equal quantities of light and heat. It is true that Herschel's hypothesis has been modified by later astronomers; but his is the credit of having directed them into the right course of inquiry and observation.
The physical constitution of the Moon was a subject which also engaged the attention of our indefatigable enthusiast. As early as 1780 he attempted the measurement of the lunar mountains, and came to the conclusion that few of them exceeded 2600 feet in height. Later research, however, has proved these figures to be inadequate. Next he addressed himself to a study of the lunar volcanoes, three of which he declared to be in a state of ignition; two of them apparently on the decline, the third still active. He was so convinced of the reality of the phenomenon, that on the 20th of April 1787 he wrote:—"The volcano burns with greater violence than it did last night." The real diameter of the volcanic light he estimated at 16,400 feet. Its intensity he described as superior to that of the nucleus of a comet then flashing across our system. The objects situated near the crater were fully illuminated by the glare of its burning matter.
It may seem strange that, after observations so exact and minute, few astronomers now admit the existence of active volcanoes in the Moon. The reasons for their incredulity are thus stated:—
The various parts of the Moon do not all reflect with the same intensity. Here, that intensity may be dependent on the form; elsewhere, on the nature of the materials. Those persons who have examined the lunar orb with telescopes, know how very considerable the difference arising from these two causes may be,—with how much keener and stronger a radiance one point of the Moon will sometimes shine than those around it. Well, it would seem to be obvious that the ratio of intensity between the brilliant parts and the faint parts must always be the same, whatever the origin of the illuminating light. In that portion of the lunar sphere which receives the glow and glory of the sun, we know that some points exist, the brightness of which is extraordinary compared with the feeble flickering gleam of those around them. And these same points, when seen in the dim reflection of the Earth, will still predominate in intensity over the neighbouring regions. In this way Arago and others explain the observations of Herschel, without admitting the existence of active volcanoes in the Moon. That volcanoes there are, is a familiar fact; but they would seem to have exhausted their activity in long-past ages. The lunar surface is now a dreary waste of rugged lava and ashes, covered with the matter ejected from craters once in a state of furious eruption. The Moon, in fact, is a world which has burned itself out. How strange the thought that in a far-back period the inhabitants of Earth, had Earth then been inhabited, might have seen the glare of countless volcanoes diffused, lurid and threatening, over the face of their satellite! How strange the thought that the once active fires should all have died away, and the Moon have thus been prepared for the better reception and reflection of the solar radiance in order to illuminate the nights of Earth!
The planets, needless to say, were the objects of Herschel's assiduous attention. Mercury was the one which least interested him; but he ascertained the perfect circularity of its disc. With respect to Venus, he endeavoured to determine the time of its rotation from 1777. We owe to him the discovery of the true shape of the "red planet Mars,"—that, like the Earth, it is an oblate spheroid, or flattened at the poles. After Piazzi, Olbers, and Harding had discovered the small planets, Ceres, Pallas, Juno, and Vesta, he applied himself to the measurement of their angular diameters. His researches led him to the conclusion that these four new bodies could not properly be ranked with the planets, and he proposed to call them Asteroids—a name now generally adopted. Since Herschel's time, the number of these minor planets known to astronomers has increased to upwards of one hundred.
With respect to Jupiter, our astronomer arrived at some important facts in connection with the duration of its rotation. He also made numerous observations on the intensities and comparative magnitudes of its satellites.
We come next in order to Saturn, the gloomy planet which the ancient astrologers regarded with so much dislike. Here, too, we find traces of Herschel's labours. Not only has he enlarged our knowledge of its equatorial compression, of its physical constitution, and of the rotation of its luminous belt or ring, but he added two to the number of its satellites. Five only of these were known at the close of the seventeenth century; of which Cussiric discovered four, and Huygens one. It was universally believed that the subject was exhausted.
But, on the 28th of August 1780, Herschel's colossal tube revealed to his delighted gaze a satellite nearer to the Saturnian ring than those previously observed. And a few days later, on the 17th of September, a seventh and last satellite crossed his field of vision. It was situated between the former and the ring; that is, it is the nearest to it of the seven.
But the most remarkable of Herschel's achievements was the discovery of the planet Uranus, and the detection of its satellites.
On the 13th of March 1781, between ten and eleven o'clock at night, the great astronomer was engaged in examining the small stars near H in the constellation Gemini, with a seven-foot telescope, bearing a magnifying power of two hundred and twenty-seven times. It appeared to him that one of these stars was of an unusual diameter; and he came to the conclusion, therefore, that it was a comet. It was under this denomination that it was discussed at the meeting of the Royal Society. But the researches of Herschel at a later period showed that the orbit of the new body was circular, and accordingly it was elevated to the rank of a planet. As already stated, Herschel named it, in compliment to George III., the Georgium Sidus; in this copying the example of Galileo with his "Medicaean stars." Afterwards, astronomers christened it Herschel, and subsequently Uranus, in conformity with the mythological nomenclature of the other planets.
The immense distance of Uranus from our Earth, its small angular diameter, and the feebleness of its light, seemed to preclude the hope that, if it were attended by satellites of the same dimensions in proportion to its own magnitude as those of the satellites of Jupiter and Saturn in proportion to their magnitude, they could be descried by any human observer. The patient, persevering, reverent temper of Herschel took no account, however, of any discouraging or unpropitious circumstances. What he did was to substitute for telescopes of the ordinary construction the new and gigantic forty-foot tube already described; and, thus, with unremitting vigilance and intense zeal, he arrived at the discovery (between January 4, 1787, and February 28, 1794) of the six satellites of Uranus; in other words, he revealed to man the completeness of a new system,—a system which will always be identified with his name.
Those singular meteors, the comets, which flash through heaven with long trails of light, and of old astonished the nations as if they were harbingers of some overwhelming calamity, were also the frequent subjects of our astronomer's investigations. He brought some of his fine and powerful instruments to bear on a comet discovered by Mr. Pigott in 1807, and closely and carefully investigated its physical constitution.
The nucleus, or head, was circular and well determined, and evidently shone by its own light. Very small stars seemed to grow pale, "to hide their diminished heads," when seen through its coma or tail. It is true, however, that this faintness may have been only apparent, and due to the circumstance of the stars being projected on a luminous background. Such was Herschel's explanation. A gaseous medium, capable of absorbing sufficient solar radiance to efface the light of some "lesser stars," appeared to him to possess in each stratum a sensible quantity of matter. Hence it would cause a real diminution of the light transmitted, though nothing would indicate the existence of such a cause.[2]
This conclusion is disputed by many astronomers.
Herschel examined the beautiful comet of 1811 with equal accuracy. "Large telescopes showed him, in the midst of the gaseous head, a rather reddish body of planetary appearance, which bore strong magnifying powers, and showed no sign of phase (that is, of change of aspect, as in the case of the Moon). Hence Herschel concluded that it was self-luminous. Yet, if we reflect that the planetary body under consideration was not a second in diameter, the absence of a phase," says Arago, "does not appear a demonstrative argument."
The same writer adds:—
"The light of the head had a bluish-green tint." Was this a real tint, or did the central reddish body, only through contrast, make the surrounding vapour appear to be coloured? Herschel did not examine the question from this point of view.
"The head of the comet appeared to be enveloped at a certain distance, on the side towards the Sun, by a brilliant narrow zone, embracing about a semicircle, and of a yellowish colour. From the two extremities of the semicircle arose, towards the region away from the Sun, two long luminous streaks which limited the tail. Between the brilliant circular semi-ring and the head, the cometary substance appeared to be dark, of great rarity, and very diaphanous.
"The luminous self-ring floated: one day it seemed to be suspended in the diaphanous atmosphere by which the head of the comet was surrounded, at a distance of 322,000 English miles from the nucleus.
"This distance was not constant. The matter of the semi-annular envelope seemed even to be precipitated by slow degrees through the diaphanous atmosphere; finally, it reached the nucleus; the earlier appearances vanished; the comet was reduced to a globular nebula.
"During its period of dissolution, the ring appeared sometimes to have several branches.
"The luminous shreds of the tail apparently underwent rapid, frequent, and considerable variations of length. Herschel discerned symptoms of a rotatory movement both in the comet and its tail; a movement which carried unequal shreds from the centre towards the border, and the border towards the centre. On examining at intervals the same region of the tail—the border, for example—sensible changes of length must have been perceptible; which, however, had no reality in them. Herschel thought that both the comet of 1811 and that of 1807 were self-luminous. The second comet of 1811 appeared to him to shine only by borrowed light. It must be acknowledged that these conjectures did not rest on anything demonstrative.
"In attentively comparing the comet of 1807 with the beautiful comet of 1811, relative to the changes of distance from the Sun, and the modifications resulting thence, Herschel put it beyond doubt that these modifications have something individual in them,—something relative to a special state of the nebulous matter. On one celestial body the changes of distance produce an enormous effect, on another the modifications are insignificant."
We have reproduced these observations by a distinguished French astronomer, in order to show the reader what was the nature, and how great was the importance, of Herschel's labours, and in how remarkable and comprehensive a manner he conducted his survey of the celestial phenomena. We now return to our brief narrative of his life.
Such a life, absorbed in tranquil and incessant studies, presents no curious, romantic, or surprising incidents. It was the life of a reverent, patient, gentle, and devoted man of genius, who dedicated himself to the task of making known the "wondrous works of God" to his fellow-men, and who in all his social and domestic relations was without blot or stain.
In 1788 he married the widow of John Pitt, Esq., with whom he received a considerable fortune, and thus for the remainder of his life he was enabled to give himself up to his favourite pursuits unembarrassed by pecuniary anxieties. His marriage was in every respect a happy one, and effectually secured his domestic peace. By his wife he had an only son,—the late Sir John Herschel,—who worthily maintained the scientific dignity of his name.
It is said, by the highest of all authority, that a prophet is not honoured in his own country. But our astronomer was not without the reward of his work, even in his lifetime. The University of Oxford conferred upon him the illustrious honorary degree of D.C.L. In 1816 he received the Guelphic order of knighthood; and in 1820 he was chosen the first president of the Astronomical Society.
From his sister's diary we gather a few particulars illustrative of his mode of life.
On the 4th of October 1806 she writes:—
"My brother came from Brighton. The same night two parties from the castle [Windsor] came to see the comet, and during the whole month my brother had not an evening to himself. As he was then in the midst of polishing the forty-foot mirror, rest became absolutely necessary after a day spent in that most laborious work; and it has ever been my opinion, that on the 14th of October his nerves received a shock of which he never got the better afterwards; for on that day (in particular) he had hardly dismissed his troop of men, when visitors assembled, and from the time it was dark till past midnight he was on the grass-plot, surrounded by between fifty and sixty persons, without having had time for putting on proper clothing, or for the least nourishment passing his lips.
"February 6th, 1807.—When I came to Slough to assist my brother in polishing the forty-foot mirror, I found my nephew[3] very ill with an inflammatory sore throat and fever.
"February 9th.—Still very ill; and my brother obliged to go on with the polishing of the great mirror, as every arrangement had been made for that purpose.—Mem. I believe my brother had reasons for choosing the cold season for this laborious work, the exertion of which alone must put any man into a fever, if he were ever so strong.
"February 10th.—From this day my nephew's health kept on mending.
"February 19th.—My nephew mending, but my brother not well.
"February 26th.—My brother so ill that I was not allowed to see him, and till March 8th his life was despaired of; and by March 10th I was permitted to see him, but only for two or three minutes, as he was not allowed to speak.
"March 22nd.—He (Sir William) went for the first time into his library, but could only remain for a few moments."
Afterwards Sir John Herschel.
From this dangerous attack Sir William recovered, but thenceforth it was clear to his friends that his strength gradually decreased, though not his enthusiasm or his industry. He persevered in his life-long labours with all his old intellectual force. What failed him was neither his tender affections nor his mental powers; but his body refused to answer all the demands made upon it by the resolute will,—the sword was slowly but surely wearing out the scabbard. Under the date of April 2, 1819, we meet with an ominous entry in his loving and faithful sister's diary:—
"My brother left Slough, accompanied by Lady Herschel, for Bath, he being very unwell; and the constant complaint of giddiness in the head so much increased, that they were obliged to be four nights on the road both going and coming. The last moments before he stepped into the carriage were spent in walking with me through his library and workrooms, pointing with anxious looks to every shelf and drawer, desiring me to examine all, and to make memorandums of them as well as I could. He was hardly able to support himself; and his spirits were so low, that I found difficulty in commanding my voice so far as to give him the assurance he should find on his return that my time had not been misspent.
"When I was left alone, I found that I had no easy task to perform, for there were packets of writings to be examined which had not been looked at for the last forty years. But I did not pass a single day without working in the library as long as I could read a letter without candlelight, and taking with me papers to copy, which employed me for best part of the night; and thus I was enabled to give my brother a clear account of what had been done at his return. But (May 1) he returned home much worse than he went, and for several days hardly noticed my handiwork."
To this same year of decay and decline (1819) belongs a small slip of yellow paper, inscribed with the following lines in a tremulous and feeble handwriting, which is jealously preserved by the illustrious astronomer's descendants:—
"LINA,—There is a great comet. I want you to assist me. Come to dine, and spend the day here. If you can come soon after one o'clock, we shall have time to prepare maps and telescopes. I saw its situation last night,—it has a long tail.
"July 4, 1819."
Then follows:—
"I keep this as a relic! Every line now traced by the hand of my dear brother becomes a treasure to me.
"C. HERSCHEL."
We know of nothing more touching in literary history than this noble, self-sacrificing, generous affection of the sister towards her eminent brother. Such instances of absolute self-denial and all-absorbing love elevate our opinion of human nature generally, and prove that something of the Divine image lingers in it still.
Herschel was now bordering upon the ripe old age of eighty, and it is no wonder that, after a life of incessant study, his strength should daily diminish. In 1822 it became painfully evident to his attached relatives and friends that the end was not far off; and on the 25th of August he passed away to his rest. We owe an account of his last days to his sister, but for whose pious care, indeed, very little of his private life would have been known, and Herschel could have been judged only from the recorded results of his immense labours.
"May 20th.—The summer proved very hot; my brother's feeble nerves were very much affected, and there being in general much company, added to the difficulty of choosing the most airy rooms for his retirement.
"July 8th.—I had a dawn of hope that my brother might regain once more a little strength, for I have a memorandum in my almanac of his walking with a firmer step than usual above three or four times the distance from the dwelling-house to the library, in order to gather and eat raspberries, in his garden, with me. But I never saw the like again.
"The latter end of July I was seized by a bilious fever, and I could for several days only rise for a few hours to go to my brother about the time he was used to see me. But one day I was entirely confined to my bed, which alarmed Lady Herschel and the family on my brother's account. Miss Baldwin it would be the immediate death if anything should happen to me."
Afterwards she wrote:—
"Of my dear nephew's advice I could not avail myself, for I knew that at that time he had weighty concerns on his mind. And, besides, my whole life almost has passed away in the delusion that, next to my eldest brother, none but Dietrich was capable of giving me advice where to leave my few relics, consisting of a few books and my sweeper [that is, the seven-foot telescope with which she was accustomed to sweep the heavens for comets]. And for the last twenty years I kept to the resolution of never opening my lips to my dear brother William about worldly concerns, let me be ever so much at a loss for knowing right from wrong."
Miss Herschel proceeds to note that on the afternoons of the 11th, 12th, 13th, and 14th of August, she, "as usual," spent some hours with her brother.
On the 15th she hastened to the accustomed place, where she generally found him, with the newspaper which she was to read aloud for his amusement. But, instead, she found assembled there several of his nearest friends, who informed her that her aged brother had been compelled to return to his room. She lost no time in seeking him. He was attended by Lady Herschel and his housekeeper, who were administering everything which was likely to keep up his failing strength.
Miss Herschel observed that he was much irritated, with the irritation natural to old age and extreme bodily feebleness, at his inability to grant a friend's request for some token of remembrance for his father. No sooner did he see Miss Herschel, the loving companion and fellow-worker of so many years, than he characteristically employed her to fetch one of his last papers, and a plate (or map) of the forty-foot telescope. "But, for the universe," says Miss Herschel, "I could not have looked twice at what I had snatched from the shelf; and when he faintly asked if the breaking up of the Milky Way[4] was in it, I said, 'Yes,' and he looked content." I cannot help remembering this circumstance; it was the last time I was sent to the library on such an occasion. That the anxious care for his papers and workrooms never ended but with his life, was proved by his frequent whispered inquiries if they were locked and the key safe; of which I took care to assure him that they were, and the key in Lady Herschel's hands.
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 passed 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 Uranus, 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.