CHAPTER VIII.

EXPEDITION TO THE CAPE.

The voyage was prosperous, but long. Nine weeks and two days passed before the welcome cry of “Land” was heard; and it was in the dawn of January 15, 1835, that Table Mountain at last stood full in view, “with all its attendant range down to the farthest point of South Africa,” outlined, ghost-like, in clear blue. The disembarkation of the instruments and luggage took several days. They filled fifteen large boats, and a single onslaught of the south-easterly gale, by which at that time of the year Cape Town is harried, might easily have marred the projected campaign. All, however, went well.

The travellers were welcomed by Dr. Stewart, one of Lady Herschel’s brothers, and enthusiastically greeted by the Royal Astronomer, Sir Thomas Maclear. They made no delay in fixing their headquarters.

“For the last two or three days,” Herschel wrote to his aunt, January 21, “we have been looking for houses, and have all but agreed for one, a most beautiful place 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 the astonishing brilliancy of the constellations.”

“The Grove” resumed its old Dutch name of “Feldhausen” during Herschel’s occupation of it; and as “Feldhausen” it will always be memorable in astronomical history as the scene of the first effective exploration of the southern heavens. The place is essentially unchanged. Only an avenue of fir-trees has been planted by way of approach to the house, a solid Dutch structure, with a disconsolate-looking garden in front; while in an adjacent field, carpeted with yellow lupins every spring, and redolent of their perfume, an obelisk has been erected on the former site of the great reflector. Above, to the west, towers the _gable-end_ of Table Mountain, and an exuberant growth of oaks and pines softens the sternness of its “mural precipices.”

The neighbourhood was, in those days, lonely in the human sense, although otherwise over- and ill-populated. Wolves and jackals abounded in the forests; venomous snakes slid through the grass; baboons had the run of the country; even the lion and the hippopotamus were scarcely yet extinct in the Cape Peninsula. Many a wild hyæna-shriek startled the astronomer at his nightly toil; and Dr. Whewell reported that he had “spent one night in tiger-hunting, but seemed to think it poor sport compared with the _chasse aux étoiles doubles_.” _Tiger_, it should be explained, is a local name for a species of leopard: no true tigers have ever been encountered in Africa.

His twenty-foot began its activity February 22nd, and the refractor, which was equatorially mounted in a revolving dome, was ready early in June. “But I am sorry to say,” he told Miss Herschel, “that the nights in which it can be used to advantage are rare.” And he lamented to his brother-in-law and intimate friend, Mr. James C. Stewart, that, during the hot season, “the stars tremble, swell, and waver most formidably.” The Cape heavens are indeed often exasperating. On nights meteorologically quite fine, the dismayed astronomer not uncommonly sees the stars “walking about” in the field of view; and a mere handful of cloud will, at other times, with incredible swiftness, spread over the whole face of the sky. Still, compensation is, sooner or later, sure to come in a run of magnificent observing weather. This was Herschel’s experience. He informed Francis Baily, October 23rd, 1834, that “the definition was far beyond anything experienced in England.” After rain especially, superb opportunities were afforded, when

“The starry sequence of nocturnal hours”[G]

[G] R. Garnett, “Iphigenia in Delphi.”

might be unbroken, perhaps for a week together, by a single adverse incident of climate.

Herschel took three specula with him to the Cape; one made by his father, another by himself with his father’s aid, and a third, of his own exclusive manufacture. Their rapid tarnishing kept them in constant circulation from the tube to the polisher. After half a dozen nights they had lost all brilliancy; at the end of three months, they were more than purblind. He acquired, however, such facility and skill in the use of his polishing machine, that he was able, in 1835, to report his mirrors as “more perfect than at any former time.”

He made astonishingly quick progress in observation. On October 24th, 1835, Miss Herschel was informed, “I have now very nearly gone over the whole southern heavens, and over much of it often. In short, I have, to use a homely phrase, broken the neck of the work, and my main object now is to secure and perfect what is done.”

His sweeps yielded a harvest of 1,202 double stars, and 1,708 nebulæ and clusters, only 439 of which had been previously registered. Among the novelties were a faint, delicate miniature of the ring-nebula in Lyra, and five planetaries. One of these he described as “of a beautiful greenish-blue colour, a full and intense tint.” This lovely object, situated in Centaur, is sometimes distinguished as “_the_ blue planetary”; although its hue is shared by all the members of its class. The nature of their spectrum, in fact, obliges them to be more or less green.

Sir John Herschel applied the term “falcated” to two curious nebulæ belonging, undoubtedly, to the later recognised “spiral” class. He perceived besides in oval nebulæ the annular lines of structure emphasised in Dr. Roberts’s photographs. He remarked, further, that “as the condensation increases toward the middle, the ellipticity of the strata diminishes.”

His study of the Magellanic Clouds gave the first idea of their composition. He showed them to be aggregations on a vast scale of every variety of cosmical product. “When examined through powerful telescopes, the constitution of the Nubeculæ, and especially of the Nubecula Major, is found to be of astonishing complexity.” He drew up a preliminary catalogue of 1,163 stars, nebulæ and clusters included in them, the conjunction of which was really decisive as to nebular status. For he showed, from the elementary principles of trigonometry, that, taking the Greater Cloud to be roughly spherical in shape, its nearest and remotest parts could differ in distance from ourselves by little more than one-tenth the distance of its centre. The fact was thus demonstrated that seventh and eighth-magnitude stars and irresolvable nebulæ co-exist within those limits. He stopped short, however, of the conclusion drawn by Whewell and Spencer, that the stellar and nebular sub-kingdoms are not only locally intermixed, but inseparably united.

The Magellanic Clouds are the most conspicuous features of the barren south polar heavens. Round the Lesser Cloud especially, the sky, Herschel said, “is most oppressively desolate.” And again: “The access to the Nubecula Minor on all sides is through a desert.” One of the separate inmates of the Larger Cloud is the “great looped nebula,” compared by Herschel to “an assemblage of loops,” the complicated windings of which make it “one of the most extraordinary objects which the heavens present.” To the eye of the present writer it resembled a shining strip of cellular tissue hung up against the sky. The “lace-work nebula” in Cygnus is of the same type; but here the tracery of nebula is closely followed by a tracery of stars. Truly, “A most wonderful phenomenon!” as Herschel exclaimed in contemplating it.

The first photographs of the Magellanic Clouds were taken in 1890–91 by Mr. Russell of Sydney. They contained an extraordinary revelation. Both objects came out in them as gigantic spirals. Their miscellaneous contents are then arranged according to the dictates of a prevalent, though unexplained cosmical law. The Nubecula Major is a double vortex, and the extent of its outlying portions, invisible except to the camera, is at least eight times that of the central mass; but they conform to the same helical lines.

Herschel catalogued 1,203 stars strewn over the surface of the famous Argo nebula, and devoted several months to its delineation. This he found “a work of great labour and difficulty.” While at the telescope he often half surrendered to despair “of ever being able to transfer to paper, with even tolerable correctness, its endless details.” “Language cannot easily convey,” he said, “a full impression of the beauty and sublimity of the spectacle this nebula offers when viewed in a sweep, ushered in by so glorious and innumerable a procession of stars, to which it forms a sort of climax.” Only the Orion nebula may be thought to surpass it in “magnitude, complexity, and brightness.” Its most characteristic feature is an abrupt vacuity, of a “lemniscate oval” shape, from which it derives the name of the “Keyhole Nebula.” The value of Herschel’s drawing of this grand object has been accentuated by its photographic portrayal. Their comparison betrays, in fact, the occurrence in the interval of what appears to be a vast change. Already, in 1871, Mr. Russell missed with surprise a prominent feature in the Feldhausen picture; and its failure to appear on photographic plates exposed for eight hours, yet impressed with innumerable stars previously unseen, raised something more than a presumption that, as Mr. Russell said, “a well-defined and brilliant portion of this nebula vanished between 1837 and 1871.” Its disappearance was independently verified by Dr. Gill, Royal Astronomer at the Cape. With a total exposure of more than twelve hours, in March, 1892, he secured a magnificent representation of this wonderful object, fundamentally agreeing with Herschel’s, save only as regards the mass of bright nebulosity vainly looked for by Mr. Russell. The “swan-shaped” or “trident-like” structure was clean gone! That is to say, the matter composing it had ceased to be luminous. It should be added that Mr. Ranyard, whose special experience lent weight to his opinion, thought it unsafe to trust much to comparisons of drawings of such baffling objects, either among themselves or with photographs.

Before leaving the Cape, Herschel witnessed an event testifying surprisingly to the _vitality_ of this nebula. In a condensed tract close to the dark “keyhole,” he was accustomed to see the bright star Eta Argûs. It gave no sign of being variable until, on December 16, 1837, he perceived with amazement that it had, all at once, nearly tripled in brightness. After this sudden leap, it mounted gradually to the level of Alpha Centauri, then slowly declined. It just matched Aldebaran when Herschel lost sight of it in March, 1838. A second, and even more vigorous outburst was watched by Sir Thomas Maclear in 1843. It then overtopped every star except Sirius, and for seven subsequent years rivalled the splendour of Canopus. No notice was at first taken of its colour; but it was redder than Mars in 1850, and reddish it still remains, in its low estate of invisibility to the naked eye. But since bright lines of hydrogen show in its photographed spectrum, we may suspect that--

“Even in its ashes live its former fires,”

and that, consequently, its vicissitudes are not yet terminated. The instability of its character was virtually discovered at Feldhausen. Except by Burchell, the African traveller, no previous suspicion of it had been entertained; the numerous facts denoting that the star’s past behaviour had been abnormal were collected by Sir John Herschel after it had been caught _in flagrante delicto_. In his belief, it had no physical connection with, but was merely projected upon, the nebula. But since then the nebular relations of blazing stars have been strongly underlined. The mass of circumstantial evidence now accumulated on the point fully warrants the assertion that Eta Argûs makes an integral part of the formation it once illuminated.

A cluster in the constellation of the Cross, unique in the varied and brilliant tints of its principal components, was compared by Herschel to “a gorgeous piece of fancy jewellery.” Within the space of 1/48th part of a square degree, he determined the places of no less than 110 of them, referred to Kappa Crucis, a rosy orb round which they are irregularly scattered. The colour-effects in this beautiful ornament of the sky need large apertures for their full display.

An object showing to the eye as a hazy star of the fourth magnitude was entitled by Bayer in 1603 Omega Centauri. Herschel’s twenty-foot disclosed it as “a noble globular cluster, beyond all comparison the richest and largest in the heavens.” Dr. Gill obtained an admirable photograph of it May 25, 1892. The stars composing it are literally countless. On a plate exposed for two hours at Arequipa, Mr. Solon I. Bailey reckoned nearly 6,400; yet he made no allowance for those “too faint and closely packed” to be perceptible except as a “mottled grey background between the distinct images.”

Somewhat inferior to Omega Centauri in size, though not at all in beauty, is 47 Toucani. So obvious is it to the naked eye that, for several nights after his arrival in Peru, Humboldt took it for a comet. Central condensation in this cluster appeared to Herschel as if marked off into three distinct stages; and to his delighted perception the whole interior offered, by its roseate hue, an exquisite contrast to the silvery radiance of the outer portions. No other observer has, however, noticed this chromatic peculiarity. The structure of 47 Toucani is almost perfectly uniform. It is broken by none of the “dark lanes,” rifts, or tunnels which so curiously diversify many globular clusters. The usual hirsute aspect lent by the spreading abroad of _tentacles_, or radiating stellar streams, is likewise scarcely distinguishable either in 47 Toucani or Omega Centauri. Indeed, Mr. Bailey noticed that the photographic images of both were all but perfectly circular. In a future age this may be otherwise. Streams of stars will, perhaps, set outward from these grand assemblages, leaving vacancies behind. Thus, if it be permissible to judge of the relative antiquity of clusters by their advance towards disruption, 47 Toucani and Omega Centauri may be reckoned among the youngest of the globular kind existing in the heavens.

The mechanism of clusters has received little attention from any astronomer beside Herschel. And a solution of an ideal case of the problem it presented was the utmost he could achieve.

“A quiescent spherical form,” he wrote in 1833, “may subsist as the bounding outline of an immense number of equal stars, uniformly distributed through its extent. In such a state of things each star might describe an ellipse in any plane, and in any direction in that plane, about the common centre without the possibility of collision. If the form be not spherical, and the distribution of the stars not homogeneous, the dynamical relations become too complicated to be distinctly apprehended.”

But the more closely these aggregations are examined, the less likely does it seem that they in any sense represent “quiescent forms.” The arrangement of the stars composing them rather suggests their being outward bound into the ocean of surrounding space, although the orders that they carry are to us sealed.

Herschel subsequently altered his views regarding the composition of clusters, and threw out in 1847 “the possibility of masses of luminous matter--of whatever density or rarity, of whatever bulk or minuteness--forming a connected system, and being prevented from collapse or from mutual interference by the resistance of a transparent and non-luminous medium.” For a “dynamical” he, in short, substituted a “statical equilibrium,” the interposed medium lending unity to the mixed aggregate, and enabling it to rotate, as a whole, upon an axis. But the rotation is more than questionable. It seems to be precluded by the ragged contours and indeterminate boundaries of all starry collections. Photographic evidence, on the other hand, favours Sir John Herschel’s surmise as to the composite nature of clusters. Some at least evidently unite within themselves the “two sidereal principles.” The stellar points they mainly consist of are immersed in, or linked together by, shining nebulous stuff.

Herschel provided a southern sequel to his father’s star-gauging work by counting 70,000 stars in 2,300 fields. Their distribution was in complete accordance with the results of the earlier experiments. “Nothing can be more striking,” Sir John wrote, “than the gradual, but rapid increase of density on either side of the Milky Way as we approach its course.” The existence of an “ecliptic of the stars” (in Lambert’s almost prophetic phrase) was demonstrated. Or, as Herschel himself put it, the plane of the Galaxy “is to sidereal, what the ecliptic is to planetary astronomy, a plane of ultimate reference, the ground-plan of the sidereal system.” He estimated, from the basis of his gauge-reckonings, that his twenty-foot reflector was capable of showing, in both hemispheres, about five and a half million stars. The smallest of these would be of 14·5 magnitude, on the strict photometric scale. But, unless his valuation was greatly too small, there must be a conspicuous falling off in stellar density beyond the region of tenth or eleventh magnitude. If this be so, scarcely one-quarter of the expected stars will make their appearance on the plates of the International Survey.

The grand feature of southern celestial scenery is the splendour of the Milky Way. One of the galactic condensations in Sagittarius actually seems to start out from the sky in a definite globular form; and the darkness of the great rift beginning near the Cross is so intensified by contrast with the strongly luminous branches it separates, as to throw the blackness of the exterior heavens _into the shade_. This part of the Milky Way may even be seen in southern latitudes--as it was by the present writer--reflected from a glassy ocean-surface. The section passing from Centaur through the Ship to Orion is, in some respects, still more striking. Captain Jacob remarked at Madras that “the general blaze from this portion of the sky is such as to render a person immediately aware of its having risen above the horizon, though he should not be at the time looking at the heavens.” Herschel commented on the singular interruptions of the shining zone by obscure spaces in Scorpio, near Alpha Centauri, and elsewhere; and admired the enhancement afforded to its magnificence by “a marvellous fringe of stars” attached pretty regularly to its southern border. “It is impossible,” he wrote to Sir William Hamilton in June, 1836, “to resist the conviction that the Milky Way is not a stratum, but a ring.”

His telescopic analysis disclosed in it a variety and complexity of structure for which he was wholly unprepared. “Great cirrous masses and streaks” of galactic light presented themselves in Sagittarius; and, as the telescope moves, the appearance is that of clouds passing in a _scud_.” “The Milky Way,” he continued, “is like sand, not strewn evenly as with a sieve, but as if flung down by handfuls, and both hands at once, leaving dark intervals, and all consisting of stars of the lowest magnitudes,” down to nebulosity, in a most astonishing manner.” As he proceeded, the stars became “inconceivably numerous and minute. There must be millions on millions, and all most unequally massed together; yet they nowhere run to nuclei, or clusters much brighter in the middle.”

In some regions, the formation proved unfathomable; all traces of stellar _texture_ disappeared. In others, it was plainly perceived to consist of portions differing exceedingly in distance, but brought by projection into nearly the same visual line. Near the Trifid Nebula, “we see foreshortened,” he said, “a vast and illimitable area scattered over with discontinuous masses and aggregates of stars, in the manner of the cumuli of a mackerel-sky, rather than of a stratum of regular thickness and homogeneous formation.”

These varied observations compelled him to reject decisively Olbers’s hypothesis of light-extinction in space. For, if the possible range of ethereal messages be restricted in one direction, it must be equally restricted in all. “We are not at liberty,” he reasoned, “to argue that in one part of the circumference of the galaxy our view is limited by this sort of cosmical veil which extinguishes the smaller magnitudes, cuts off the nebulous light of distant masses, and closes our view in impenetrable darkness; while, at another, we are compelled, by the clearest evidence telescopes can afford, to believe that star-strewn spaces _lie open_, exhausting their powers and stretching out beyond their utmost reach.” These objections seem fatal to what we may call the “agnostic” theory of the sidereal world--the theory that investigations into its construction are for ever barred by failure of the means of communication--that we can never see more than a necessarily meaningless part of a possibly infinite, and, in any case, absolutely inscrutable whole.

The general telescopic exploration of the Milky Way began and ended with the Herschels. Their great reflectors have been superseded by the photographic camera. This particular application of its versatile powers encountered special difficulties; but they were happily overcome by Professor Barnard in July, 1889. A six-inch portrait lens afforded the two chief requisites of a powerful light-grasp and an extensive field; and plates exposed with it for some three hours showed accordingly, for the first time, “in all their delicacy and beauty” (to quote Professor Barnard’s words), “the vast and wonderful cloud-forms, with their remarkable structure of lanes, holes, and black gaps, and sprays of stars, as no eye or telescope can ever hope to see them.” The work has since been continued by him and others, notably by Mr. Russell at Sydney, and by Professor Max Wolf at Heidelberg, so that the complete round of the “circling zone” will, before long, have its varied aspects permanently recorded. They frequently present strange and significant forms. Branching, leaf-like, spiral, elliptical structures abound; individual stars are disposed in circlets, streams, parallel rows, curves of sundry kinds. A “clustering power” of unknown nature is ubiquitously active; orderly development is in progress. A creative purpose can be _felt_, although it cannot be distinctly followed by the mind.

Herschel’s “sweeps” in southern skies were continued until January, 1838; but with frequent intermissions. He was ready for every interesting object that came in his way--comets among the rest. “Encke’s--_yours_,” he informed his aunt, October 24, 1835, “escaped me owing to trees and the Table Mountain, though I cut away a good gap in our principal oak avenue to get at it.” Four days later he caught sight of Halley’s comet at its second predicted return. But for the stellar aspect of this body his observations of it would have begun much earlier; for, in the absence of an exact ephemeris, it was impossible to pick it out from among the stars it long precisely counterfeited. “I am sure,” he said, “that I must often have swept with a night-glass over the very spot where it stood in the mornings before sunrise; and never was surprise greater than mine at seeing it riding high in the sky, broadly visible to the naked eye, when pointed out to me by a note from Mr. Maclear, who saw it with no less amazement on the 24th.”

“This comet,” he wrote to Miss Herschel, March 8, 1836, “has been a great interruption to my sweeps, and I _hope_ and _fear_ it may yet be visible another month.” It lingered on just two. He watched with astonishment the changes it underwent. “Within the well-defined head,” he wrote in his “Cape Observations,” “and somewhat eccentrically placed, was seen a vividly luminous nucleus, or rather, an object which I know no better way to describe than by calling it a miniature comet, having a nucleus, head, and tail of its own, perfectly distinct, and considerably exceeding in intensity of light the nebulous disc or envelope.”

This strangely organised body was a very Proteus for instability of form. It alternately lost and recovered its tail. It contracted into the likeness of a star, then dilated into a nebulous globe, which at last vanished as if through indefinite diffusion. The whole mass “seemed touched, seemed turned to finest air.” During one week at the end of January--it had passed perihelion November 16--Sir John estimated that the cometary Amœba had increased its bulk no less than forty times!

The paraboloidal form characteristic of this comet and many others, was to him “inconceivable,” apart from the play of repulsive, in addition to attractive forces; and he suggested that high electrical excitement due to vaporisation, if of the same kind with a permanent charge on the sun, would plausibly account for the enigmatical appearances he had witnessed. From their close study at Königsberg, Bessel had already concluded “the emission of the tail to be a purely electrical phenomenon.”

In March, 1836, Herschel attacked the subject of southern stellar photometry. Carrying further the “method of sequences,” he determined the relative brightness of nearly five hundred stars, which he disposed in order on a single descending scale, and linked on by careful comparisons to the northern stars, as they “lightened into view” on the homeward voyage. By the device of an “artificial standard star,” he was besides enabled to obtain numerical values for the lustre of each star examined, in terms of that of Alpha Centauri. Most important of all, he rectified the current system of magnitudes, and introduced a definite “light ratio,” which has since been extended, and more strictly defined, but not altered.

His “astrometer” gave Herschel the means of _balancing_ the lustre of Alpha Centauri against full moonlight. The latter proved to be 27,500 times more powerful. And Wollaston having determined the ratio of moonlight to sunlight at 1/800000 (corrected by Zöllner to 1/600000), it became feasible to compare the brightness of any particular star, _as we see it_, with the brightness of the sun. Alpha Centauri, for example, sends us, according to Herschel, 1/22 thousand millionth of the light we receive from our domestic luminary. Moreover, when the distance of the star came to be measured (it amounts to twenty-five billions of miles), _light received_ could at once be translated into _light emitted_. And the result has been to show that the components of this splendid binary are, taken together, four times more luminous than the sun. Through Sir John Herschel’s photometric researches, then, the real light-power of stars at known distances became an ascertainable quantity; and it is an element of great importance to astrophysical inquiries.

On January 10, 1837, he wrote from Feldhausen to his brother-in-law: “I am now at work on the spots in the sun, and the general subject of solar radiation.” The sun was just then at an exceptionally high maximum of disturbance. Spots of enormous size frequently obscured its disc. One was estimated by Herschel, March 29, 1837, to cover, independently of others, an area of 3,780 millions of square miles. So that it considerably exceeded in dimensions the great spot-group of February, 1892, the largest ever photographed at Greenwich. The study of a series of such phenomena led him to propound the “cyclone-theory” of their origin. It marked a decided advance in solar physics, if only because it rested upon the fact--until then unaccountably overlooked--that spot-production is intimately connected with the sun’s rotation. He regarded it as a kind of disturbance incidental to a system of fluid circulation analogous to the terrestrial trade- and anti-trade winds. “The spots,” he said, “in this view of the subject would come to be assimilated to those regions on the earth’s surface where, for the moment, hurricanes and tornadoes prevail; the upper stratum being temporarily carried downwards, displacing by its impetus the two strata of luminous matter beneath, the upper of course to a greater extent than the lower, and thus wholly or partially denuding the opaque surface of the sun below.”

But the fundamental cause of our atmosphere’s flow and counter-flow is absent in the sun. The earth is heated from the outside, and therefore unequally; hence the air rushes along, turning westward as it goes, from the chilly poles to the torrid zone of vertical sunshine. No reason is, however, apparent why the solar equator should be hotter than the solar poles. That adduced by Herschel is certainly inadequate. He supposed that, by a retention of heat at the equator due to the accumulation there, consequent upon his rotation, of the sun’s absorbing atmosphere, a difference of temperature might be maintained sufficient to keep the solar trade-winds blowing. But the effect is too slight to be detected. And, in fact, the main drift of the photospheric layers is along parallels of latitude. Polar and equatorial currents are insignificant and uncertain.

Herschel and Pouillet contemporaneously, although at opposite sides of the globe, succeeded in 1837 in measuring the intensity of solar radiation. They were the first to apprehend the true bearings of the question, which in principle are simple enough. All that is required is to determine the heating effects, in a given time, of direct sunshine. Its despoilment by our air has, indeed, to be allowed for. Here the chief element of uncertainty comes in. Herschel put the loss at one-third the original thermal power of vertical rays; Pouillet pronounced it nearly one-half; Langley, using the most refined appliances, concludes it to be four-tenths. Striking an average between his own and the French results, Herschel calculated that, at the sun’s surface, a shell of ice forty feet thick would melt in one minute, the rate being reduced, at the distance of the earth, to an inch in two hours and twelve minutes. And it is now practically certain that this estimate was too small by about half its amount.

By way of illustrating the effects obtained with his philosophical apparatus, he constructed a popular kind of actinometer, in the shape of an “American dispatch,” made of a few pieces of wood and two panes of glass, in which eggs were roasted, and beef-steaks broiled, by sun-heat alone. The viands thus _cosmically cooked_ were “eaten with no small relish by the entertained bystanders.”

Mimas and Enceladus, Saturn’s innermost moons, had persistently eluded Herschel’s search for them in England; but, to his great delight, both favoured him at the Cape. His observations of them in 1835–6 were the first since his father’s time. The next detection of Mimas was by Mr. Lassell in 1846.

The extent, variety, and completeness of the work done at Feldhausen strike one with ever-fresh admiration. It seems scarcely credible that so much was accomplished in four years by a single unaided individual. Herschel’s only assistant was an honest mechanic named John Stone, faithful, serviceable, in his way skilful, but not a “being” of the “quick as lightning” sort, imagined and realised by Caroline Herschel. It is related that during his observations of Halley’s comet, Sir John on one occasion fell asleep, and while he remained in this condition of peril (owing to the elevation and insecurity of his perch), Stone kept dutifully turning the telescope. At last the astronomer awoke, rubbed his eyes, looked down the great tube, saw nothing, rubbed his eyes again, and exclaimed, “Why, John, where’s the comet?” The comet had meantime set, and the telescope was duly directed towards its place behind Table Mountain!

The splendid fulfilment of his astronomical tasks did not represent the whole of Herschel’s activity at the Cape. He collected a large store of tidal data for Dr. Whewell; started scientific meteorology; established a system of national education still working beneficially, and presided over the South African Literary and Scientific Institution, the members of which presented him with a gold medal on his departure. His visit made an epoch in the development of the Colony.

To himself personally it was a time of intense enjoyment. His labours, arduous though they were, proceeded calmly, disembarrassed from jostling claims and counter-claims. They were carried on with absorbed enthusiasm, inspired in part by their sublime nature, in part by the excitement of novelty. His family throve and multiplied at Feldhausen. Sir Thomas Maclear’s friendship supplied unfailing social pleasure. An exhilarating climate, moreover, enchanting scenery, translucent skies, blossoming glens and hillsides worthy of Maeldune’s Isle of Flowers, contributed to render his southern sojourn a radiant episode. He wrote of it to Mr. Stewart as “the sunny spot in my whole life, where my memory will always love to bask.” But “the dream,” he added, “was too sweet not to be dashed by the dread of awakening.” The spell was broken when in the middle of March, 1838, he sailed in the _Windsor Castle_ for England.

The interest created by his romantic expedition spread to the other side of the Atlantic. A grotesque narrative, published in the _New York Sun_ for September, 1835, of lunar discoveries made at the Cape with the combined aid of the twenty-foot reflector and the Drummond limelight, was eagerly read and believed by thousands, was reprinted, re-circulated, and re-read. Nor were common gulls the only victims to the hoax. The truth of the story was gravely debated by the Paris Academy of Sciences.

Herschel’s home-coming was a triumph. He was overwhelmed with applause and gratulation. His fellow-countrymen offered him what compensation they could for the disappearance from his horizon of the Southern Cross. He was created a baronet at the Queen’s Coronation, received an honorary degree of D.C.L. at Oxford in 1839, and was offered, but declined, reimbursement from the Treasury for the entire cost of his trip. He peremptorily refused as well to represent the University of Cambridge in Parliament, or to be nominated for the Presidentship of the Royal Society. His utmost desire was for a quiet and laborious life. A banquet, however, given in honour of his return, June 15, 1838, could not be shunned; the less so that the celebration had a typical character. “In honouring a man,” Sir William Hamilton said, in proposing his health, “we honour science too.” For “the cultivators and lovers of Science have chosen Herschel for their chief--say, rather, have as such received him by inheritance.”