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salary was not paid with very great regularity. Sir William therefore established a regular manufacture of telescopes, of which he and his sister ground all the mirrors, and superintended all the details. Though money for necessary household expenses, as well as for astronomical purposes, was thus acquired, Herschel felt keenly that he was doing an injustice to himself and to the cause of astronomy by giving up his time to the making of telescopes for other observers. Mention is made in the journals of several telescopes of remarkable dimensions. One for the King of Spain was executed at a cost of 31507. Miss Herschel notes that she was much hindered in her work by the packing of the Spanish telescope, which was done at the barn and rickyard of Upton, where she was then lodging, her own room being all the time filled with the optical apparatus. The Prince of Canino paid 23107. for a ten- and a seven-foot telescope from the same indefatigable hands. It is evident that though the pecuniary profit was great, it was dearly purchased at the expense of health and time which was entailed upon Sir William by labour so severe. There is no doubt that the exhaustion produced by grinding mirrors told seriously upon his health.

In the summer which saw them installed at Slough Miss Herschel appeared as an original discoverer. Sir William was called away to deliver a ten-foot telescope as a present from the King to the Observatory of Göttingen. While he was absent, Miss Herschel resumed her 'sweeping,' for which her position as assistant usually left her but little time, but to which she was intensely devoted. Her diary on the 1st of August, 1786, contains the following entry :

"This evening I saw an object which I believe will prove to-morrow night to be a comet.'

All next day she steadily pursued her daily task, but it is plain that her mind was running on her comet.

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August 2. To-day I calculated 150 nebula-I fear it will not be clear to-night, it has been raining throughout the whole day, but now seems to clear up a little. One o'clock: the object of last night is a comet.'

Before going to bed that night she wrote to several of the principal astronomers to announce her discovery. To Dr. Blagden she says:

The employment of writing down the observations when my brother uses the 20-foot reflector, does not often allow me time to look at the heavens; but as he is now on a visit to Germany, I have taken the opportunity to sweep in the neighbourhood of the sun in search of comets, and last night I found an object very much re

sembling

sembling in colour and brightness the 27 nebule of the "Connoissance des Temps," &c.'

She then describes the position and appearance of the 'suspected comet,' as she calls it, and adds that her observations were made with a Newtonian sweeper of twenty-seven-inch focal length, and a power of about twenty.

'Sweeping,' which was such a delight to Miss Herschel, consists in directing the telescope to a given point in the heavens, and allowing it to remain in that position. By the motion of the earth, all stars situated on the parallel of declination (or distance from the equator) to which the instrument is directed pass across the field in their order of right ascension, and can be recognised by reference to a clock showing sidereal time. When any star or nebula is observed where, according to the catalogues, no star should be, it is noted for further investigation. In one of her letters, many years afterwards,* to Sir John Herschel, Miss Herschel mentions the contrivance by which she used to obtain the time. You mention a monkeyclock, or jack, in your paper. I would only notice (if you mean the jack in the painted deal-case) that Alex made it merely to take with me on the roof when I was sweeping for comets, that I might count seconds by it, going softly downstairs till I was within hearing of the beat of the timepiece on the ground-floor (at that time our Observatory), all doors being open.'

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Miss Herschel's remark, that she was sweeping in the neighbourhood of the sun,' is possibly an error in the transcription of her letter. The sun had disappeared on the day in question by half-past seven; and had that luminary been above the visible horizon, his rays would have prevented the comet from being observed if it had been anywhere in his vicinity. From Miss Herschel's description of the comet's position (in the constellation Coma Bernices), it was on the day of the discovery about three hours later than the sun in right ascension, and therefore would pass the meridian about three o'clock in the day; at ten in the evening it would be in the north-western heavens, and not very far from the horizon. It is possible that this is what Miss Herschel means by 'the neighbourhood of the sun.'

The same post which conveyed her letter to Dr. Blagden took also one to her friend M. Aubert, who sent in reply a warm letter of congratulation :

'I wish you joy,' he says, 'most sincerely on the discovery. I am more pleased than you can well conceive that you have made it, and I

* December, 1826, p. 207.

think I see your wonderfully clever and wonderfully amiable brother, upon the news of it, shed a tear of joy. You have immortalised your name, and you deserve such a reward from the Being who has ordered all these things to move as we find them for your assiduity in the business of astronomy, and for your love for so celebrated and so deserving a brother.'

Το any other woman such a success would have been a subject at least of some exaltation, but she had no thought for herself. On her brother's return she resumed her place as his humble and unknown assistant without a regret for the career of original distinction which she was foregoing. First and last, Caroline Herschel discovered eight comets. Her journals usually contain such an entry as this:-' August —, 2 A.M., discovered a comet ;' and the letter-book of the next day contains transcripts of communications to the astronomers of her own and other nations, giving its declination and right ascension, and 'commending it to their protection'-of her own labours or success never one solitary word. Many years afterwards she said, with characteristic modesty, that it was all chance; I never called a comet mine till several post-days passed without any account of them coming to hand. And after all, it is only like the children's game, "Wer am ersten kick ruft, soll den Apfel haben.”*

On the 8th of May, 1788, Sir William Herschel married. His wife was a lady of great amiability, and she brought him a fortune which enabled him thenceforth to pursue his scientific career without any anxiety about money matters. Sir William was made happy, but it was the great grief of Caroline Herschel's life. She resigned, as she said, her position as housekeeper, and lived henceforth in lodgings, coming every day to her work, and in all respects continuing the same labours, as her brother's assistant and secretary:

'But,' says the authoress of the 'Memoir,'' it is not to be supposed that a nature so strong and a heart so affectionate should accept the new state of things without much and bitter suffering. To resign the supreme place by her brother's side which she had filled for sixteen years with such hearty devotion could not be otherwise than painful in any case; but how much more so in this where equal devotion to the same pursuit must have made identity of interest and purpose as complete as it is rare! One who could both feel and express herself so strongly was not likely to fall into her new place without some outward expression of what it cost her-tradition confirms the assumption, and it is easy to understand how this long significant silence † is

Whoever first calls "kick" shall have the apple.'-Letter to Lady Herschel, July, 1842, p. 326.

† She destroyed all her journals and letters from 1788 to 1798.

due

due to the light of later wisdom and calmer judgment, which counselled the destruction of all record of what was likely to be painful to survivors.'

It is evident from her diary, which was resumed in 1798though the entries thenceforward are exceedingly brief and business-like-that she never lived beneath her brother's roof again. During his absence from home she would go to his house and put things in order for him; little passages show that at such times she was always at work for him, polishing the brass-work of his telescopes, making curtains for his bookselves, cataloguing his books and papers; but the day before his expected return she would go back to her lodgings again, whence she would emerge only at nightfall to take her share of the duty of 'minding the heavens,' as she used to call it. Her brother made her a new telescope, which to the end of his life was her most cherished possession. Letter after letter she used to write during her old age, making arrangements that it should be in safe hands, which would use it tenderly when she was dead. Its ultimate fate is thus spoken of in a letter from Sir John Herschel

The telescopes are now, I trust, properly disposed of. Mr. Hausmann (who will value it) has the sweeper. The five-feet Newtonian Reflector is in the hands of the Royal Astronomical Society, and it will be preserved by it, as the little telescope of Newton is by the Royal Society, long after I and all the little ones are dead and gone.'

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The ten years which succeeded her brother's marriage were among the most laborious of Caroline Herschel's life. The Royal Society published two of her works, namely A Catalogue of 860 Stars, observed by Flamsteed, but not included in the British Catalogue,' and 'A General Index of Reference to every Observation of every Star in the British Catalogue.' But the most laborious, as well as the most valuable, of her works was the 'Reduction and Arrangement in the form of a Catalogue of all the Star-clusters and Nebulæ observed by Sir William Herschel in his Sweeps.' It was for this that the Gold Medal of the Royal Astronomical Society was conferred upon her, and the extraordinary distinction of an Honorary Membership.

We cannot follow Sir William Herschel through the laborious years which followed. They were a time of intense activity. Not a year passed that he did not signalise with some important memoir in the Philosophical Transactions.' He demonstrated what had hitherto been only suspected, that the sun was not the

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Vol. 141.-No. 282.

* August 10, 1840.

2 B

stable

stable centre of the universe, but that it, together with the planets which form the solar system, was changing its position among the stars. He showed that the direction of our course through space-in company with the sun, our master, and the planets, our companions-is in the direction of the constellation Hercules. It is a fact calculated strongly to impress the imagination, that the sun himself is but a star, among millions brighter, probably, and grander than himself, and that he and all his system of attendant worlds are darting with inconceivable rapidity towards a definite point in space. The establishment of this circumstance in the orderly organisation of the universe would alone have made Herschel's name famous. But it is thrown into the shade by other discoveries still more calculated to strike the mind with awe.

There is no branch of astronomy which Herschel might more justly claim for his own domain than that which relates to clustered stars. The catalogue of Meissier contained but sixty-eight nebulæ, to which Lacaille afterwards added twenty-eight, and they were looked upon as mere tracts of luminous matter: their real nature was not suspected. But as soon as Herschel applied to them his powerful instruments, his rare penetration and unconquerable perseverance, this branch of science took a rapid stride. In 1796 he published in the Philosophical Transactions' a catalogue of one thousand nebulæ or clusters of stars. Three years later appeared a second catalogue, quite as extensive as the first; and that, again, was followed, in 1802, by a third catalogue of five hundred nebulæ.

Two thousand five hundred nebulæ !' exclaims Arago; such was the contingent supplied by Herschel to a branch of astronomy which had hardly been touched before him. But he was not content with simple discovery. It was his rare good fortune to demonstrate their true nature.

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One single nebula out of the vast contingent' mentioned by Arago, resolved itself under Herschel's telescope into a cluster of fourteen thousand stars! And though not all the nebulæ are resolvable into similar clusters, it is demonstrated by his, and by subsequent observations, that thousands of these beautiful objects are clusters of innumerable stars, so immeasurably distant from us that only their collective light is visible—a dimly luminous point in boundless space.

The immense distance of the planet Uranus, its small angular diameter, and the feebleness of its light, long forbade any hope of discerning from the earth its satellites, if any such existed. It was to the great forty-feet telescope, invented and built by Herschel, that the discovery was due at last. His perseverance

was

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