Caroline Lucretia Herschel was born at Hanover, March 16th, 1750, and was thus more than eleven years younger than the brother with whose name hers is inseparably associated. She remembered the panic caused by the earthquake of 1755, and her experience barely fell short of the political earthquake of 1848; but the fundamental impressions of her long life were connected with “minding the heavens.”

She was of little account in her family, except as a menial. Her father, indeed, a man of high character and cultivated mind, thought much of her future, and wished to improve her prospects by giving her some accomplishments. So he taught her to play the violin well enough to take part in concerted music. But her instruction was practicable only when her mother was out of the way, or in a particularly good humour. Essentially a “Hausfrau,” Anna Ilse had no sympathy with aspirations. She was hard-working and well-meaning, but narrow and inflexible, and she kept her second daughter strictly to household drudgery. Her literary education, accordingly, got no farther than reading and writing; even the third “R” was denied to her. But she was carefully trained in plain sewing and knitting, and supplied her four brothers with stockings from so early an age that the first specimen of her workmanship touched the ground while she stood upright finishing the toe!

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.”

William Herschel was now an appendage to the court of George III. He had to live near Windsor, and a large dilapidated house on Datchet Common was secured as likely to meet his unusual requirements. The “flitting” took place August 1, 1782. William was in the highest spirits. There were stables available for workrooms and furnaces; a spacious laundry that could be turned into a library; a fine lawn for the accommodation of the great reflector. Crumbling walls and holes in the roof gave him little or no concern; and if butcher's meat was appallingly dear (as his sister lamented) the family could live on bacon and eggs! In this sunny spirit he entered upon the career of untold possibilities that lay before him.

Nevertheless the King's astronomer did not find it all plain sailing. His primary duty was to gratify the royal taste for astronomy, and this involved no trifling expenditure of time and toil. The transport of the seven-foot to the Queen's lodge could be managed in the daylight, but its return-journey in the dark, after the conclusion of the celestial raree-show, was an expensive and a risky business; yet fetched back it should be unless a clear night were to be wasted—a thing not possible to contemplate.

Herschel's career as an observing astronomer came to a virtual end with his departure from the Cape. He was then forty-six, two years younger than his father when he began his course of prodigious activity at Slough. Sir William's craving to see and to know was insatiable; Sir John's was appeased by the accomplishment of one grand enterprise. His was a many-sided mind; dormant interests of sundry kinds revived on the first opportunity; new ones sprang up; and curiosity to interrogate the skies ceased to “prick the sides of his intent.” So the instruments taken down at Feldhausen in 1838 were not remounted in England; and their owner is never again recorded to have used a telescope. One cannot but regret that, in the plenitude of his powers, and instructed by rare experience, he should have put by his weapons of discovery. The immense stock of observations with which they had furnished him remained, it is true, in their primitive, rough-hewn state; and he may have considered that wise husbandry required him to save one harvest before planting another. This, at any rate, was the course that he pursued.

But it was often and in many ways interrupted. The demands on his time and thoughts were innumerable.

The chief authority for the Life of Sir William Herschel is Mrs. John Herschel's “Memoir of Caroline Herschel” (London, 1876). It embodies Caroline's Journals and Recollections, the accuracy of which is above suspicion. William himself, indeed, referred to her for dates connected with his early life. The collateral sources of information are few and meagre: they yield mere gleanings, yet gleanings worth collecting. Professor E. S. Holden has had recourse to many of them for his excellent little monograph entitled “Herschel, his Life and Works” (London, 1881), which is usefully supplemented by “A Synopsis of the Scientific Writings of Sir William Herschel,” prepared by the same author with the aid of Professor Hastings. It made part of the Smithsonian Report for 1880, and was printed separately at Washington in 1881. But the wonderful series of papers it summarises have still to be sought, one by one, by those desiring to study them effectually, in the various volumes of the Philosophical Transactions in which they originally appeared. Their collection and republication is, nevertheless, a recognised desideratum, and would fill a conspicuous gap in scientific literature.

Sir John Herschel's life has yet to be written. The published materials for it are scanty, although they have been reinforced by the inclusion in the late Mr. Graves's “Life of Sir William Rowan Hamilton” (Dublin, 1882-9) of his correspondence with that remarkable man.

William Herschel was descended from one of three brothers, whose Lutheran opinions made it expedient for them to quit Moravia early in the seventeenth century. Hans Herschel thereupon settled as a brewer at Pirna, in Saxony; his son Abraham rose to some repute as a landscape-gardener in the royal service at Dresden; and Abraham's youngest son, Isaac, brought into the world with him, in 1707, an irresistible instinct and aptitude for music. Having studied at Berlin, he made his way in 1731 to Hanover, where he was immediately appointed oboist in the band of the Hanoverian Guard. A year later he married Anna Ilse Moritzen, by whom he had ten children. The fourth of these, Frederick William, known to fame as William Herschel, was born November 15th, 1738.

His brilliant faculties quickly displayed themselves. At the garrison-school he easily distanced his brother Jacob, his senior by four years, and learned besides, privately, whatever French and mathematics the master could teach him. He showed also a pronounced talent for music, and was already, at fourteen, a proficient on the hautboy and violin. In this direction lay his manifest destiny. His father was now bandmaster of the Guard; he was poor, and had no other provision to give his sons than to train them in his own art; and thus William, driven by necessity to become self-supporting while still a boy, entered the band as oboist in 1753.

“A Knowledge of the construction of the heavens,” Herschel wrote in 1811, “has always been the ultimate object of my observations.” The “Construction of the Heavens”! A phrase of profound and novel import, for the invention of which he was ridiculed by Brougham in the Edinburgh Review; yet expressing, as it had never been expressed before, the essential idea of sidereal astronomy. Speculation there had been as to the manner in which the stars were grouped together; but the touchstone of reality had yet to be applied to them. This unattempted, and all but impossible enterprise Herschel deliberately undertook. It presented itself spontaneously to his mind-as worth the expenditure of a life's labour; and he spared nothing in the disbursement. The hope of its accomplishment inspired his early exertions, carried him through innumerable difficulties, lent him audacity, fortified him in perseverance. For this,

and burst his way into an unnavigated ocean.

Herschel has had very few equals in his strength of controlled imagination. He held the balance, even to a nicety, between the real and the ideal. Meditation served in him to prescribe and guide experience; experience to ripen the fruit of meditation.

Could the whole of Sir John Herschel's astronomical career be obliterated, and the whole of his contributions to pure mathematics be forgotten, he would still merit celebrity as a physicist. Experimental optics, above all, engaged his attention. “Light,” he himself said, “was his first love,” and he was never wholly forgetful of it. In 1830 he described himself as “forcibly drawn aside from his optical studies” by the claims of nebulae and double stars. How strong he felt those claims to be, can best be understood by considering the firmness with which he averted his mind, out of regard to them, from the intricate and bewitching subject of his early devotion.

“In understand from Peacock,” Dr. Whewell wrote to him, June 19, 1818, “that you are untwisting light like whipcord, examining every ray that passes within half a mile, and putting the awful question, ‘Polarised, or not polarised?’ to thousands that were never before suspected of any intention but that of moving in a straight line.” These interrogatories brought out a remarkable diversity in the action upon light of quartz, and other similar substances, corresponding with the two different modes of crystallisation belonging to each of them. Here, in Lord Kelvin's phrase, is “one of the most notable meeting-places between natural history and natural philosophy.”

Double stars were, when Herschel began to pay attention to them, regarded as mere chance productions. No suspicion was entertained that a real, physical bond united their components. Only the Jesuit astronomer, Christian Mayer, maintained that bright stars were often attended by faint ones; and since his observations were not such as to inspire much confidence, his assertions counted for very little. “In my opinion,” Herschel wrote in 1782, “it is much too soon to form any theories of small stars revolving round large ones.” He, indeed, probably even then, suspected that close equal stars formed genuine couples; but he waited, if so, for evidence of the connection. The chief subject of his experiments on parallax was Epsilon Boötis, an exquisitely tinted, unequal pair. But he soon became aware that either stellar parallax was elusively small, or that he was on the wrong track for detecting it. And, since his favourite stars have proved to be a binary combination, it was, of course, drawing water in a sieve to make one the test of perspective shifting in the other.

The number of Herschel's double stars alone showed them to be integral parts of an express design. Such a crop of casualties was out of all reasonable question.

The powers of the telescope were so unexpectedly increased, that they may almost be said to have been discovered by William Herschel. No one before him had considered the advantages of large apertures. No one had seemed to remember that the primary function of an instrument designed to aid vision is to collect light. The elementary principle of space-penetration had not been adverted to. It devolved upon him to point out that the distances of similar objects are exactly proportional to the size of the telescopes barely sufficing to show them. The reason is obvious. Compare, for instance, a one-inch telescope with the naked eye. The telescope brings to a focus twenty-five times as much light as can enter the pupil, taken at one-fifth of an inch in diameter; therefore it will render visible a star twenty-five times fainter than the smallest seen without its help; or—what comes to the same thing—an intrinsically equal star at a five-fold distance. A one-inch glass hence actually quintuples the diameter of the visible universe, and gives access to seventy-five times the volume of space ranged through by the unassisted eye.

This simple law Herschel made the foundation-stone of his sidereal edifice. He was the first to notice it, because he was the first practically to concern himself with the star-depths.

“The little boy is entertaining, comical, and promising,” Dr. Burney wrote after his visit to Slough in 1797. John Frederick William Herschel was then five years old, having been born “within the shadow of the great telescope” March 7, 1792. He was an industrious little fellow, especially in doing mischief. “When one day I was sitting beside him,” his aunt relates, “listening to his prattle, my attention was drawn by his hammering to see what he might be about, and I found that it was the continuation of many days' labour, and that the ground about the corner of the house was undermined, the corner-stone entirely away, and he was hard at work going on with the next. I gave the alarm, and old John Wiltshire, a favourite carpenter, came running, crying out, ‘God bless the boy, if he is not going to pull the house down!’” And she wrote to him at Feldhausen; “I see you now in idea, running about in petticoats among your father's carpenters, working with little tools of your own, and John Wiltshire crying out, ‘Dang the boy, if he can't drive in a nail as well as I can!’”

“John and I,” she told his wife, “were the most affectionate friends, and many a half or whole holiday spent with me was dedicated to making experiments in chemistry, in which generally all boxes, tops of tea-canisters, pepper-boxes, teacups, etc., served for the necessary vessels, and the sand-tub furnished the matter to be analysed.