Sir William Herschel: His Life and Works Part 3

relating to central forces other than the force of gravity, which are or may be concerned in the construction of the sidereal heavens. This early idea was still entertained by HERSCHEL in 1789, and the mathematical papers referred to must be contained in the _Minutes_ of the Society, which on its dissolution were torn from the Minute-book and returned to the writers.

The earliest published writing of HERSCHEL is the answer to the prize question in the "Ladies' Diary" for 1779, proposed by the celebrated LANDEN, namely:

"The length, tension, and weight of a musical string being given, it is required to find how many vibrations it will make in a given time, when a small given weight is fastened to its middle and vibrates with it."

In the _Philosophical Transactions_ of the Royal Society for 1780, are two papers of his. The t.i.tle of the first is, _Astronomical Observations on the Periodical Star in Collo Ceti_, by Mr. WILLIAM HERSCHEL, of Bath.

This was communicated to the Society by Dr. WILLIAM WATSON, Jr., and was read May 11, 1780, at the same time as the other paper on the mountains of the moon. It is to be noted that HERSCHEL was at this time plain "Mr. WILLIAM HERSCHEL, of Bath." It was only in 1786 that he became "Dr. HERSCHEL," through the Oxford degree of LL.D.

Neither of these two papers is specially remarkable on its purely astronomical side. The problems examined were such as lay open before all, and the treatment of them was such as would naturally be suggested.

The second of these two contained, however, a short description of his Newtonian telescope, and he speaks of it with a just pride: "I believe that for distinctness of vision this instrument is perhaps equal to any that was ever made." He was, at least, certain of having obtained excellence in the making of his instruments.

In his next paper, however, read January 11, 1781, a subject is approached which shows a different kind of thought. It is the first obvious proof of the truth of the statement which he made long afterwards (1811), when he said: "A knowledge of the construction of the heavens has always been the ultimate object of my observations."

The t.i.tle of this paper was _Astronomical Observations on the Rotation of the Planets round their Axes, made with a view to determine whether the Earth's diurnal motion is perfectly equable_. Here the question is a difficult and a remote one, and the method adopted for its solution is perfectly suitable in principle. It marks a step onward from mere observations to philosophizing upon their results. In practical astronomy, too, we note an advance. Not only are his results given, but also careful estimates of the errors to be feared in them, and a discussion of the sources of such errors. The same volume of the _Philosophical Transactions_ which contains this paper, also contains another, _Account of a Comet_, read April 26, 1781. This comet was the major planet _Ura.n.u.s_, or, as HERSCHEL named it, _Georgium Sidus_.

He had found it on the night of Tuesday, March 13, 1781. "In examining the small stars in the neighborhood of H _Geminorum_, I perceived one that appeared visibly larger than the rest; being struck with its uncommon appearance, I compared it to H _Geminorum_ and the small star in the quartile between _Auriga_ and _Gemini_, and finding it so much larger than either of them, I suspected it to be a comet." The "comet" was observed over all Europe. Its...o...b..t was computed by various astronomers, and its distance from the sun was found to be nineteen times that of our earth. This was no comet, but a new major planet. The discovery of the amateur astronomer of Bath was the most striking since the invention of the telescope. It had absolutely no parallel, for every other major planet had been known from time immemorial.[13]

The effect of the discoveries of GALILEO was felt almost more in the moral than in the scientific world. The mystic number of the planets was broken up by the introduction of four satellites to _Jupiter_. That _Venus_ emulated the phases of our moon, overthrew superst.i.tion and seated the Copernican theory firmly. The discovery of "an innumerable mult.i.tude of fixed stars" in the Milky Way confounded the received ideas. This was the great mission of the telescope in GALILEO'S hands.

The epoch of mere astronomical discovery began with the detection of the large satellite of _Saturn_ by HUYGHENS, in 1655. Even then superst.i.tion was not dead. HUYGHENS did not search for more moons, because by that discovery he had raised the number of known satellites to six,[14] and because these, with the six planets, made "the perfect number twelve."

From 1671 to 1684 Ca.s.sINI discovered four more moons revolving about _Saturn_. Since 1684 no new body had been added to the solar system.

It was thought complete for nearly a century.

In England, the remarkable discoveries of BRADLEY (1727-62) had been in the field of practical astronomy, and his example had set the key-note for further researches. France was just about beginning the brilliant period of her discoveries in mathematical astronomy, and had no observatory devoted to investigations like HERSCHEL'S, with the possible exception of DARQUIER'S and FLAUGERGUES'. The observatories of SCHROETER and VON HAHN, in Germany, were not yet active. The field which HERSCHEL was created to fill was vacant, the whole world over. It was especially so in England. The Royal Observatory at Greenwich, under MASKELYNE, a skilful observer, whose work was mostly confined to meridian observations, was no rival to a private observatory like HERSCHEL'S. The private observatories themselves were but small affairs; those of the king, at Kew, of Dr. WILSON, at Glasgow, of Mr. AUBERT, at Loampit Hill, of the Count VON BRUHL, in London, being perhaps the most important.

The whole field was open. What was perhaps more remarkable, there was in England, during HERSCHEL'S lifetime, no astronomer, public or private, whose talents, even as an observer, lay in the same direction.

It hardly need be said that as a philosopher in his science, he had then no rival, as he has had none since. His only a.s.sociates even, were MICh.e.l.l and WILSON.[15]

Without depreciating the abilities of the astronomers of England, his cotemporaries, we may fairly say that HERSCHEL stood a great man among a group of small ones.

Let us endeavor to appreciate the change effected in the state of astronomy not only in England but in the whole world, simply by the discovery of _Ura.n.u.s_. Suppose, for example, that the last planet in our system had been _Saturn_. No doubt HERSCHEL would have gone on. In spite of one and another difficulty, he would have made his ten-foot, his twenty-foot telescopes. His forty-foot would never have been built, and the two satellites which he found with it might not have been discovered. Certainly _Mimas_ would not have been. His researches on the construction of the heavens would have been made; those were in his brain, and must have been ultimated. The ma.s.s of observations of _Saturn_, of _Jupiter_, of _Mars_, of _Venus_, would have been made and published. The researches on the sun, on the "invisible rays" of heat, on comets and nebulae--all these might have been made, printed, and read.

But these would have gone into the _Philosophical Transactions_ as the work of an amateur astronomer, "Mr. HERSCHEL, of Bath." They would have been praised, and they would have been doubted. It would have taken a whole generation to have appreciated them. They would have been severely tried, entirely on their merits, and finally they would have stood where they stand to-day--unrivalled. But through what increased labors these successes would have been gained! It is not merely that the patronage of the king, the subsidies for the forty-foot telescope (4,000), the comparative ease of HERSCHEL'S life would have been lacking. It is more than this. It would have been necessary for him to have created the audience to which he appealed, and to have conquered the most persistent of enemies--indifference.

Certainly, if HERSCHEL'S mind had been other than it was, the discovery of _Ura.n.u.s_, which brought him honors from every scientific society in the world, and which gave him authority, might have had a hurtful effect. But, as he was, there was nothing which could have aided his career more than this startling discovery. It was needed for him. It completed the solar system far more by affording a free play to a profoundly philosophical mind, than by occupying the vacant s.p.a.ces beyond _Saturn_.

His opportunities would have been profoundly modified, though his personal worth would have been the same.

"The Star that from the zenith darts its beams, Visible though it be to half the earth, Though half a sphere be conscious of its brightness, Is yet of no diviner origin, No purer essence, than the One that burns Like an untended watchfire, on the ridge Of some dark mountain; or than those that seem Humbly to hang, like twinkling winter lamps, Among the branches of the leafless trees."

To show how completely unknown the private astronomer of Bath was at this time, I transcribe a sentence from BODE'S account of the discovery of _Ura.n.u.s_.

"In the _Gazette Litteraire_ of June, 1781, this worthy man is called MERSTHEL; in JULIUS' _Journal Encyclopedique_, HERTSCHEL; in a letter from Mr. MASKELYNE to M. MESSIER, HERTHEL; in another letter of MASKELYNE'S to Herr MAYER, at Mannheim, HERRSCh.e.l.l; M.

DARQUIER calls him HERMSTEL. What may his name be? He must have been born a _German_."[16]

This obscurity did not long continue. The news spread quickly from fas.h.i.+onable Bath to London. On the 6th of December, 1781, HERSCHEL was elected a Fellow of the Royal Society, to which he was formally "admitted" May 30, 1782. He was forty-three years old.

He also received the Copley medal in 1781 for his "discovery of a new and singular star."[17]

. . . "He was now frequently interrupted by visitors who were introduced by some of his resident scholars, among whom I remember Sir HARRY ENGELFIELD, Dr. BLAGDEN, and Dr. MASKELYNE. With the latter he was engaged in a long conversation, which to me sounded like quarrelling, and the first words my brother said after he was gone were: 'That is a devil of a fellow.'. . .

"I suppose their names were often not known, or were forgotten; for it was not till the year 1782 or 1783 that a memorandum of the names of visitors was thought of.". . . "My brother now applied himself to perfect his mirrors, erecting in his garden a stand for his twenty-foot telescope; many trials were necessary before the required motions for such an unwieldy machine could be contrived.

Many attempts were made by way of experiment before an intended thirty-foot telescope could be completed, for which, between whiles (not interrupting the observations with seven, ten, and twenty-foot, and writing papers for both the Royal and Bath Philosophical Societies), gauges, shapes, weight, etc., of the mirror were calculated, and trials of the composition of the metal were made. In short, I saw nothing else and heard nothing else talked of but these things when my brothers were together. ALEX. was always very alert, a.s.sisting when anything new was going forward, but he wanted perseverance, and never liked to confine himself at home for many hours together. And so it happened that my brother WILLIAM was obliged to make trial of my abilities in copying for him catalogues, tables, etc., and sometimes whole papers which were lent him for his perusal. Among them was one by Mr. MICh.e.l.l and a catalogue of CHRISTIAN MAYER, in Latin, which kept me employed when my brother was at the telescope at night. When I found that a hand was sometimes wanted when any particular measures were to be made with the lamp micrometer, etc., or a fire to be kept up, or a dish of coffee necessary during a long night's watching, I undertook with pleasure what others might have thought a hards.h.i.+p. . . . Since the discovery of the _Georgium Sidus_ [March 13, 1781], I believe few men of learning or consequence left Bath before they had seen and conversed with its discoverer, and thought themselves fortunate in finding him at home on their repeated visits. Sir WILLIAM WATSON was almost an intimate, for hardly a day pa.s.sed but he had something to communicate from the letters which he received from Sir JOSEPH BANKS, and other members of the Royal Society, from which it appeared that my brother was expected in town to receive the gold medal. The end of November was the most precarious season for absenting himself. But Sir WILLIAM WATSON went with him, and it was arranged so that they set out with the diligence at night, and by that means his absence did not last above three or four days, when my brother returned alone, Sir WILLIAM remaining with his father.

"Now a very busy winter was commencing; for my brother had engaged himself to conduct the oratorios conjointly with RONZINI, and had made himself answerable for the payment of the engaged performers, for his credit ever stood high in the opinion of every one he had to deal with. (He lost considerably by this arrangement.) But, though at times much hara.s.sed with business, the mirror for the thirty-foot reflector was never out of his mind, and if a minute could but be spared in going from one scholar to another, or giving one the slip, he called at home to see how the men went on with the furnace, which was built in a room below, even with the garden.

"The mirror was to be cast in a mould of loam, of which an immense quant.i.ty was to be pounded in a mortar and sifted through a fine sieve. It was an endless piece of work, and served me for many an hour's exercise; and ALEX. frequently took his turn at it, for we were all eager to do something towards the great undertaking. Even Sir WILLIAM WATSON would sometimes take the pestle from me when he found me in the work-room, where he expected to find his friend, in whose concerns he took so much interest that he felt much disappointed at not being allowed to pay for the metal. But I do not think my brother ever accepted pecuniary a.s.sistance from any one of his friends, and on this occasion he declined the offer by saying it was paid for already.

"Among the Bath visitors were many philosophical gentlemen who used to frequent the levees at St. James's, when in town. Colonel WALSH, in particular, informed my brother that from a conversation he had had with His Majesty, it appeared that in the spring he was to come with his seven-foot telescope to the king. Similar reports he received from many others, but they made no great impression nor caused any interruption in his occupation or study, and as soon as the season for the concerts was over, and the mould, etc., in readiness, a day was set apart for casting, and the metal was in the furnace. Unfortunately it began to leak at the moment when ready for pouring, and both my brothers and the caster, with his men, were obliged to run out at opposite doors, for the stone flooring (which ought to have been taken up) flew about in all directions as high as the ceiling. Before the second casting was attempted, everything which could insure success had been attended to, and a very perfect metal was found in the mould.

"But a total stop and derangement now took place, and nearly six or seven months elapsed before my brother could return to the undisturbed enjoyment of his instruments and observations. For one morning in Pa.s.sion Week, as Sir WILLIAM WATSON was with my brother, talking about the pending journey to town, my eldest nephew arrived to pay us a visit, and brought the confirmation that his uncle was expected with his instrument in town. . . . We had not one night in the week, except Friday, but what was set apart for an oratorio either at Bath or Bristol. Soon after Easter, a new organ being erected in St. James's Church, it was opened with two performances of the 'Messiah;' this again took up some of my brother's time.". . .

In May of 1782 HERSCHEL went to London.

"But when almost double the time had elapsed which my brother could safely be absent from his scholars, ALEX., as well as myself, were much at a loss how to answer their inquiries, for, from the letters we received, we could learn nothing but that he had been introduced to the king and queen, and had permission to come to the concerts at Buckingham House, where the king conversed with him about astronomy."

It was during his absence at this time that the three following letters were written and received:

"DEAR LINA:--

"I have had an audience of His Majesty this morning, and met with a very gracious reception. I presented him with the drawing of the solar system, and had the honor of explaining it to him and the queen. My telescope is in three weeks' time to go to Richmond, and meanwhile to be put up at Greenwich, where I shall accordingly carry it to-day. So you see, LINA, that you must not think of seeing me in less than a month. I shall write to Miss LEE myself; and other scholars who inquire for me, you may tell that I cannot wait on them till His Majesty shall be pleased to give me leave to return, or rather to dismiss me, for till then I must attend. I will also write to Mr. PALMER to acquaint him with it.

"I am in a great hurry, therefore can write no more at present.

Tell ALEXANDER that everything looks very likely as if I were to stay here. The king inquired after him, and after my great speculum. He also gave me leave to come to hear the GRIESBACHS play at the private concert which he has every evening. My having seen the king need not be kept a secret, but about my staying here it will be best not to say anything, but only that I must remain here till His Majesty has observed the planets with my telescope.

"Yesterday I dined with Colonel WALSH, who inquired after you. There were Mr. AUBERT and Dr. MASKELYNE. Dr. MASKELYNE in public declared his obligations to me for having introduced to them the high powers, for Mr. AUBERT has so much succeeded with them that he says he looks down upon 200, 300, or 400 with contempt, and immediately begins with 800. He has used 2,500 very completely, and seen my fine double stars with them. All my papers are printing, with the postscript and all, and are allowed to be very valuable. You see, LINA, I tell you all these things. You know vanity is not my foible, therefore I need not fear your censure. Farewell.

"I am, your affectionate brother,

"WM. HERSCHEL.

"Sat.u.r.day Morning,

"probably _May 25, 1782_."

TO MISS HERSCHEL.

"Monday Evening, _June 3, 1782._

"DEAR LINA:--

"I pa.s.s my time between Greenwich and London agreeably enough, but am rather at a loss for work that I like. Company is not always pleasing, and I would much rather be polis.h.i.+ng a speculum. Last Friday I was at the king's concert to hear GEORGE play. The king spoke to me as soon as he saw me, and kept me in conversation for half an hour. He asked GEORGE to play a solo-concerto on purpose that I might hear him; and GEORGE plays extremely well, is very much improved, and the king likes him very much. These two last nights I have been star-gazing at Greenwich with Dr. MASKELYNE and Mr.

AUBERT. We have compared our telescopes together, and mine was found very superior to any of the Royal Observatory. Double stars which they could not see with their instruments I had the pleasure to show them very plainly, and my mechanism is so much approved of that Dr. MASKELYNE has already ordered a model to be taken from mine, and a stand to be made by it to his reflector. He is, however, now so much out of love with his instrument that he begins to doubt whether it _deserves_ a new stand.

"I am introduced to the best company. To-morrow I dine at Lord PALMERSTON'S, next day with Sir JOSEPH BANKS, etc., etc. Among opticians and astronomers nothing now is talked of but _what they call_ my great discoveries. Alas! this shows how far they are behind, when such trifles as I have seen and done are called _great_. Let me but get at it again! I will make such telescopes, and see such things--that is, I will endeavor to do so."