Great Astronomers by Robert Stawell Ball (best ereader for students .txt) 📖

will be able to sympathise with the enthusiastic delight

of Kepler when at last, after years of toil, the glorious light

broke forth, and that which he considered to be the greatest of

his astonishing laws first dawned upon him. Kepler rightly judged

that the number of days which a planet required to perform its

voyage round the sun must be connected in some manner with the

distance from the planet to the sun; that is to say, with the

radius of the planet’s orbit, inasmuch as we may for our present

object regard the planet’s orbit as circular.

 

Here, again, in his search for the unknown law, Kepler had no

accurate dynamical principles to guide his steps. Of course, we

now know not only what the connection between the planet’s

distance and the planet’s periodic time actually is, but we also

know that it is a necessary consequence of the law of universal

gravitation. Kepler, it is true, was not without certain surmises

on the subject, but they were of the most fanciful description.

His notions of the planets, accurate as they were in certain

important respects, were mixed up with vague ideas as to the

properties of metals and the geometrical relations of the

regular solids. Above all, his reasoning was penetrated by the

supposed astrological influences of the stars and their

significant relation to human fate. Under the influence of such a

farrago of notions, Kepler resolved to make all sorts of trials in

his search for the connection between the distance of a planet

from the sun and the time in which the revolution of that planet

was accomplished.

 

It was quite easily demonstrated that the greater the distance of

the planet from the sun the longer was the time required for its

journey. It might have been thought that the time would be

directly proportional to the distance. It was, however, easy to

show that this supposition did not agree with the fact. Finding

that this simple relation would not do, Kepler undertook a vast

series of calculations to find out the true method of expressing

the connection. At last, after many vain attempts, he found, to

his indescribable joy, that the square of the time in which a

planet revolves around the sun was proportional to the cube of the

average distance of the planet from that body.

 

The extraordinary way in which Kepler’s views on celestial matters

were associated with the wildest speculations, is well illustrated

in the work in which he propounded his splendid discovery just

referred to. The announcement of the law connecting the distances

of the planets from the sun with their periodic times, was then

mixed up with a preposterous conception about the properties of

the different planets. They were supposed to be associated with

some profound music of the spheres inaudible to human ears, and

performed only for the benefit of that being whose soul formed the

animating spirit of the sun.

 

Kepler was also the first astronomer who ever ventured to predict

the occurrence of that remarkable phenomenon, the transit of a

planet in front of the sun’s disc. He published, in 1629, a

notice to the curious in things celestial, in which he announced

that both of the planets, Mercury and Venus, were to make a

transit across the sun on specified days in the winter of 1631.

The transit of Mercury was duly observed by Gassendi, and the

transit of Venus also took place, though, as we now know, the

circumstances were such that it was not possible for the

phenomenon to be witnessed by any European astronomer.

 

In addition to Kepler’s discoveries already mentioned, with which

his name will be for ever associated, his claim on the gratitude

of astronomers chiefly depends on the publication of his famous

Rudolphine tables. In this remarkable work means are provided for

finding the places of the planets with far greater accuracy than

had previously been attainable.

 

Kepler, it must be always remembered, was not an astronomical

observer. It was his function to deal with the observations made

by Tycho, and, from close study and comparison of the results, to

work out the movements of the heavenly bodies. It was, in fact,

Tycho who provided as it were the raw material, while it was the

genius of Kepler which wrought that material into a beautiful and

serviceable form. For more than a century the Rudolphine tables

were regarded as a standard astronomical work. In these days we

are accustomed to find the movements of the heavenly bodies set

forth with all desirable exactitude in the NAUTICAL ALMANACK,

and the similar publication issued by foreign Governments. Let it

be remembered that it was Kepler who first imparted the proper

impulse in this direction.

 

[PLATE: THE COMMEMORATION OF THE RUDOLPHINE TABLES.]

 

When Kepler was twenty-six he married an heiress from Styria, who,

though only twenty-three years old, had already had some

experience in matrimony. Her first husband had died; and it was

after her second husband had divorced her that she received the

addresses of Kepler. It will not be surprising to hear that his

domestic affairs do not appear to have been particularly happy,

and his wife died in 1611. Two years later, undeterred by the

want of success in his first venture, he sought a second partner,

and he evidently determined not to make a mistake this time.

Indeed, the methodical manner in which he made his choice of the

lady to whom he should propose has been duly set forth by him and

preserved for our edification. With some self-assurance he

asserts that there were no fewer than eleven spinsters desirous of

sharing his joys and sorrows. He has carefully estimated and

recorded the merits and demerits of each of these would-be brides.

The result of his deliberations was that he awarded himself to an

orphan girl, destitute even of a portion. Success attended his

choice, and his second marriage seems to have proved a much more

suitable union than his first. He had five children by the first

wife and seven by the second.

 

The years of Kepler’s middle life were sorely distracted by a

trouble which, though not uncommon in those days, is one which we

find it difficult to realise at the present time. His mother,

Catherine Kepler, had attained undesirable notoriety by the

suspicion that she was guilty of witchcraft. Years were spent in

legal investigations, and it was only after unceasing exertions on

the part of the astronomer for upwards of a twelvemonth that he

was finally able to procure her acquittal and release from prison.

 

It is interesting for us to note that at one time there was a

proposal that Kepler should forsake his native country and adopt

England as a home. It arose in this wise. The great man was

distressed throughout the greater part of his life by pecuniary

anxieties. Finding him in a strait of this description, the

English ambassador in Venice, Sir Henry Wotton, in the year 1620,

besought Kepler to come over to England, where he assured him that

he would obtain a favourable reception, and where, he was able to

add, Kepler’s great scientific work was already highly esteemed.

But his efforts were unavailing; Kepler would not leave his own

country. He was then forty-nine years of age, and doubtless a

home in a foreign land, where people spoke a strange tongue, had

not sufficient attraction for him, even when accompanied with the

substantial inducements which the ambassador was able to offer.

Had Kepler accepted this invitation, he would, in transferring his

home to England, have anticipated the similar change which took

place in the career of another great astronomer two centuries

later. It will be remembered that Herschel, in his younger days,

did transfer himself to England, and thus gave to England the

imperishable fame of association with his triumphs.

 

The publication of the Rudolphine tables of the celestial

movements entailed much expense. A considerable part of this was

defrayed by the Government at Venice but the balance occasioned no

little trouble and anxiety to Kepler. No doubt the authorities

of those days were even less Willing to spend money on scientific

matters than are the Governments of more recent times. For

several years the imperial Treasury was importuned to relieve him

from his anxieties. The effects of so much worry, and of the long

journeys which were involved, at last broke down Kepler’s health

completely. As we have already mentioned, he had never been

strong

from infancy, and he finally succumbed to a fever in November,

1630, at the age of fifty-nine. He was interred at St. Peter’s

Church at Ratisbon.

 

Though Kepler had not those personal characteristics which have

made his great predecessor, Tycho Brahe, such a romantic figure,

yet a picturesque element in Kepler’s character is not wanting.

It was, however, of an intellectual kind. His imagination, as

well as his reasoning faculties, always worked together. He was

incessantly prompted by the most extraordinary speculations. The

great majority of them were in a high degree wild and chimerical,

but every now and then one of his fancies struck right to the

heart of nature, and an immortal truth was brought to light.

 

I remember visiting the observatory of one of our greatest modern

astronomers, and in a large desk he showed me a multitude of

photographs which he had attempted but which had not been

successful, and then he showed me the few and rare pictures which

had succeeded, and by which important truths had been revealed.

With a felicity of expression which I have often since thought of,

he alluded to the contents of the desk as the “chips.” They were

useless, but they were necessary incidents in the truly successful

work. So it is in all great and good work. Even the most skilful

man of science pursues many a wrong scent. Time after time he

goes off on some track that plays him false. The greater the

man’s genius and intellectual resource, the more numerous will be

the ventures which he makes, and the great majority of those

ventures are certain to be fruitless. They are in fact, the

“chips.” In Kepler’s case the chips were numerous enough.

They were of the most extraordinary variety and structure.

But every now and then a sublime discovery was made of such a

character as to make us regard even the most fantastic of Kepler’s

chips with the greatest veneration and respect.

 

ISAAC NEWTON.

 

It was just a year after the death of Galileo, that an infant came

into the world who was christened Isaac Newton. Even the great

fame of Galileo himself must be relegated to a second place in

comparison with that of the philosopher who first expounded the

true theory of the universe.

 

Isaac Newton was born on the 25th of December (old style), 1642,

at Woolsthorpe, in Lincolnshire, about a half-mile from

Colsterworth, and eight miles south of Grantham. His father,

Mr. Isaac Newton, had died a few months after his marriage to

Harriet Ayscough, the daughter of Mr. James Ayscough, of Market

Overton, in Rutlandshire. The little Isaac was at first so

excessively frail and weakly that his life was despaired of.

The watchful mother, however, tended her delicate child with such

success that he seems to have thriven better than might have been

expected from the circumstances of his infancy, and he ultimately

acquired a frame strong enough to outlast the ordinary span of

human life.

 

For three years they continued to live at Woolsthorpe, the widow’s

means of livelihood being supplemented by the income from another

small estate at Sewstern, in a neighbouring part of

Leicestershire.

 

[PLATE: WOOLSTHORPE MANOR.

Showing solar dial made by Newton when a boy.]

 

In 1645, Mrs. Newton took as a second husband the Rev. Barnabas

Smith, and on