Sir William Herschel: His Life and Works Part 5

"Immediately every preparation for beginning the great work commenced. A very ingenious smith (CAMPION), who was seeking employment, was secured by my brother, and a temporary forge erected in an upstairs room."

The sale of these telescopes of HERSCHEL'S must have produced a large sum, for he had made before 1795 more than two hundred seven-feet, one hundred and fifty ten-feet, and eighty twenty-feet mirrors. For many of the telescopes sent abroad no stands were constructed. The mirrors and eye-pieces alone were furnished, and a drawing of the stand sent with them by which the mirrors could be mounted.

In 1785 the cost of a seven-foot telescope, six and four-tenths inches aperture, stand, eye-pieces, etc., complete, was two hundred guineas, a ten-foot was six hundred guineas, and a twenty-foot about 2,500 to 3,000 guineas. He had made four ten-foot telescopes like this for the king.

In 1787 SCHROETER got the mirrors and eye-pieces only for a four-and-three-quarter-inch reflector for five guineas; those for his seven-foot telescope were twenty-three guineas. Later a seven-foot telescope, complete, was sold for one hundred guineas, and the twenty-five-foot reflector, made for the Madrid observatory, cost them 75,000 francs = $15,000.[19] It was ordered in 1796, but not delivered for several years, the Spanish government being short of money. For a ten and a seven foot telescope, the Prince of Canino paid 2,310.

VON MAGELLAN writes to BODE concerning a visit to HERSCHEL:[20]

"I spent the night of the 6th of January at HERSCHEL'S, in Datchet, near Windsor, and had the good luck to hit on a fine evening. He has his twenty-foot Newtonian telescope in the open air and mounted in his garden very simply and conveniently. It is moved by an a.s.sistant, who stands below it. . . . Near the instrument is a clock regulated to sidereal time. . . . In the room near it sits HERSCHEL'S sister, and she has FLAMSTEED'S Atlas open before her. As he gives her the word, she writes down the declination and right ascension and the other circ.u.mstances of the observation. In this way HERSCHEL examines the whole sky without omitting the least part. He commonly observes with a magnifying power of one hundred and fifty, and is sure that after four or five years he will have pa.s.sed in review every object above our horizon. He showed me the book in which his observations up to this time are written, and I am astonished at the great number of them. Each sweep covers 2 15' in declination, and he lets each star pa.s.s at least three times through the field of his telescope, so that it is impossible that anything can escape him. He has already found about 900 double stars and almost as many nebulae. I went to bed about one o'clock, and up to that time, he had found that night four or five new nebulae. The thermometer in the garden stood at 13 Fahrenheit; but, in spite of this, HERSCHEL observes the whole night through, except that he stops every three or four hours and goes in the room for a few moments. For some years HERSCHEL has observed the heavens every hour when the weather is clear, and this always in the open air, because he says that the telescope only performs well when it is at the same temperature as the air. He protects himself against the weather by putting on more clothing. He has an excellent const.i.tution, and thinks about nothing else in the world but the celestial bodies. He has promised me in the most cordial way, entirely in the service of astronomy, and without thinking of his own interest, to see to the telescopes I have ordered for European observatories, and he will himself attend to the preparation of the mirrors."

It was at this time, 1783, May 8, that HERSCHEL married. His wife was the daughter of Mr. JAMES BALDWIN, a merchant of the city of London, and the widow of JOHN PITT, Esq. She is described as a lady of singular amiability and gentleness of character. She was entirely interested in his scientific pursuits, and the jointure which she brought removed all further anxiety about money affairs. They had but one child, JOHN FREDERICK WILLIAM, born March 7, 1792.[21]

The house at Datchet became more and more unfit for the needs of the family, and in June, 1785, a move was made to Clay Hall, in Old Windsor.

The residence here was but short, and finally a last change was made to Slough on April, 3d, 1786.

The ardor of the work during these years can be judged of by a single sentence from CAROLINA HERSCHEL'S diary:

"The last night at Clay Hall was spent in sweeping till daylight, and by the next evening the telescope stood ready for observation at Slough."

From 1786 until his death, HERSCHEL remained at Slough; his life, truly speaking, was in his observatory.

It is indeed true, as ARAGO has said in his eloquent tribute to him: "On peut dire hardiment du jardin et de la pet.i.te maison de Slough, que c'est le lieu du monde ou il a ete fait le plus de decouvertes. Le nom de ce village ne perira pas; les sciences le transmettront religieus.e.m.e.nt a nos derniers neveux."

HERSCHEL'S first contribution to the _Philosophical Transactions_ was printed in the volume for 1780, his last in that for 1818. Of these thirty-nine volumes, there are only two (1813 and 1817) which contain no paper from his hand, and many volumes contain more than one, as he published no less than sixty-eight memoirs in this place.

And yet it must not be thought that his was an austere and grave existence. Music, which he loved to enthusiasm, was still a delight to him. All the more that his devotion was free. The glimpses which we get of his life with his friends show him always cheerful, ardent, and devoted. Even in his later years, he had not lost a "boyish earnestness to explain;" his simplicity and the charm of his manner struck every one.

"HERSCHEL, you know, and everybody knows, is one of the most pleasing and well-bred natural characters of the present age," says Dr. BURNEY, who had opportunity to know.

The portrait which is given in the frontispiece must have been painted about this time (1788), and the eager, ardent face shows his inner life far better than any words can do.

Even in his scientific writings, which everything conspired to render grave and sober, the almost poetic nature of his mind shows forth. In one of his (unpublished) note-books, now in the Royal Society's library, I found this entry:

"640th Sweep--November 28, 1786.--The nebula of _Orion_, which I saw by the front view, was so glaring and beautiful that I could not think of taking any place of its extent."

He was quite alone under the perfectly silent sky when this was written, and he was at his post simply to make this and other such observations.

But the sky was beautiful to him, and his faithful sister, CAROLINA, sitting below, has preserved for us the words as they dropped from his lips.

On the 11th of January, 1787, HERSCHEL discovered two satellites to _Ura.n.u.s_.

After he had well a.s.sured himself of their existence, but before he communicated his discovery to the world, he made this crucial test. He prepared a sketch of _Ura.n.u.s_ attended by his two satellites, as it would appear on the night of February 10, 1787, and when the night came, "the heavens displayed the original of my drawings, by showing in the situation I had delineated them _the Georgian planet attended by two satellites_. I confess that this scene appeared to me with additional beauty, as the little secondary planets seemed to give a dignity to the primary one which raises it into a more conspicuous situation among the great bodies of the solar system.". . .

In a memoir of 1789, he has a few sentences which show the living way in which the heavens appeared to him:

"This method of viewing the heavens seems to throw them into a new kind of light.

"They are now seen to resemble a luxuriant garden, which contains the greatest variety of productions in different flourishing beds; and one advantage we may at least reap from it is, that we can, as it were, extend the range of our experience to an immense duration.

For is it not almost the same thing whether we live successively to witness the germination, blooming, foliage, fecundity, fading, withering, and corruption of a plant, or whether a vast number of specimens selected from every stage through which the plant pa.s.ses in the course of its existence be brought at once to our view?"

The thought here is no less finely expressed than it is profound. The simile is perfect, if we have the power to separate among the vast variety each state of being from every other, and if the very luxuriance of ill.u.s.tration in the heavens does not bewilder and overpower the mind.

It was precisely this discriminating power that HERSCHEL possessed in perfection.

There is a kind of humor in the way he records a change of opinion:

"I formerly supposed the surface of _Saturn's_ ring to be rough, owing to luminous points like mountains seen on it, till one of these was kind enough to venture off the edge of the ring and appear as a satellite."

In 1782 he replies with a certain concealed sharpness to the idea that he used magnifying powers which were too high. There is a tone almost of impatience, as if he were conscious he was replying to a criticism based on ignorance:

"We are told that we gain nothing by magnifying too much. I grant it; but shall never believe I magnify too much till by experience I find that I can see better with a lower power." (1782.)

By 1786, when he returns to this subject, in answer to a formal request to explain his use of high magnifiers, he is quite over any irritation, and treats the subject almost with playfulness:

"Soon after my first essay of using high powers with the Newtonian telescope, I began to doubt whether an opinion which has been entertained by several eminent authors, 'that vision will grow indistinct when the optic pencils are less than the fiftieth part of an inch,' would hold good in all cases. I perceived that according to this criterion I was not ent.i.tled to see distinctly with a power of much more than about 320 in a seven-foot telescope of an aperture of six and four-tenths inches, whereas in many experiments I found myself very well pleased with magnifiers which far exceeded such narrow limits. This induced me, as it were, by way of apology to myself for seeing well where I ought to have seen less distinctly, to make a few experiments."

It is needless to say that these experiments proved that from the point of view taken by HERSCHEL, he was quite right, and that his high powers had numerous valuable applications. He goes on to say:

"Had it not been for a late conversation with some of my highly esteemed and learned friends, I might probably have left the papers on which these experiments were recorded, among the rest of those that are laid aside, when they have afforded me the information I want."

The last sentence seems to be a kind of notice to his learned friends that there is yet more unsaid. As a warning to those to whose criticisms he had replied, he gives them this picture of the kind of a.s.siduity which will be required, if some of his observations on double stars are to be repeated:

"It is in vain to look for these stars if every circ.u.mstance is not favorable. The observer as well as the instrument must have been long enough out in the open air to acquire the same temperature. In very cold weather an hour at least will be required." (1782.)

We may gain some further insight into his character from the following chance extracts from his writings:

"I have all along had truth and reality in view as the sole object of my endeavors." (1782.)

"Not being satisfied when I thought it possible to obtain more accurate measures, I employed [a more delicate apparatus]." (1783.)

"To this end I have already begun a series of observations upon several zones of double stars, and should the result of them be against these conjectures, I shall be the first to point out their fallacy." (1783.)

"There is a great probability of succeeding still farther in this laborious but delightful research, so as to be able at last to say not only how much the annual parallax _is not_, but how much it really _is_." (1782.)

The nature of his philosophizing, and the limits which he set to himself, may be more clearly seen in further extracts:

"By taking more time [before printing these observations] I should undoubtedly be enabled to speak more confidently of the _interior_ _construction of the heavens_, and of its various _nebulous_ and sidereal strata. As an apology for this prematurity it may be said that, the end of all discoveries being communication, we can never be too ready in giving facts and observations, whatever we may be in reasoning upon them." (1785.)

"In an investigation of this delicate nature we ought to avoid two opposite extremes. If we indulge a fanciful imagination, and build worlds of our own, we must not wonder at our going wide from the path of truth and nature. On the other hand, if we add observation to observation without attempting to draw not only certain conclusions but also conjectural views from them, we offend against the very end for which only observations ought to be made. I will endeavor to keep a proper medium, but if I should deviate from that, I could wish not to fall into the latter error." (1785.)

"As observations carefully made should always take the lead of theories, I shall not be concerned if what I have to say contradicts what has been said in my last paper on this subject." (1790.)

No course of reasoning could be more simple, more exact, more profound, and more beautiful than this which follows:

"As it has been shown that the spherical figure of a cl.u.s.ter is owing to the action of central powers, it follows that those cl.u.s.ters which, _caeteris paribus_, are the most complete in this figure, must have been the longest exposed to the action of these causes. Thus the maturity of a sidereal system may be judged from the disposition of the component parts.

"Hence planetary nebulae may be looked on as very aged. Though we cannot see any individual nebula pa.s.s through all its stages of life, we can select particular ones in each peculiar stage." (1789.)