Great Astronomers - Robert Stawell Ball (the little red hen ebook .TXT) 📗

that is to say, we

have to determine the errors in the positions of our telescopes

and the errors in the going of our clocks, and then we have to

determine what the observations would have been had our telescopes

been absolutely perfect, and had our clocks been absolutely

correct. There are also many other matters which have to be

attended to in order to reduce our observations so as to obtain

from the figures as yielded to the observer at the telescope the

actual quantities which it is his object to determine.

 

The work of effecting these reductions is generally a very

intricate and laborious matter, so that it has not unfrequently

happened that while observations have accumulated in an

observatory, yet the tedious duty of reducing these observations

has been allowed to fall into arrear. When Airy entered on his

duties at Greenwich he found there an enormous mass of

observations which, though implicitly containing materials of the

greatest value to astronomers, were, in their unreduced form,

entirely unavailable for any useful purpose. He, therefore,

devoted himself to coping with the reduction of the observations

of his predecessors. He framed systematic methods by which the

reductions were to be effected, and he so arranged the work that

little more than careful attention to numerical accuracy

would be required for the conduct of the operations. Encouraged

by the Admiralty, for it is under this department that Greenwich

Observatory is placed, the Astronomer Royal employed a large force

of computers to deal with the work. BY his energy and admirable

organisation he managed to reduce an extremely valuable series of

planetary observations, and to publish the results, which have

been of the greatest importance to astronomical investigation.

 

The Astronomer Royal was a capable, practical engineer as well

as an optician, and he presently occupied himself by designing

astronomical instruments of improved pattern, which should

replace the antiquated instruments he found in the observatory.

In the course of years the entire equipment underwent a total

transformation. He ordered a great meridian circle, every part

of which may be said to have been formed from his own designs.

He also designed the mounting for a fine equatorial telescope

worked by a driving clock, which he had himself invented.

Gradually the establishment at Greenwich waxed great under his

incessant care. It was the custom for the observatory to be

inspected every year by a board of visitors, whose chairman was

the President of the Royal Society. At each annual visitation,

held on the first Saturday in June, the visitors received a report

from the Astronomer Royal, in which he set forth the business

which had been accomplished during the past year. It was on these

occasions that applications were made to the Admiralty, either for

new instruments or for developing the work of the observatory in

some other way. After the more official business of the

inspection was over, the observatory was thrown open to visitors,

and hundreds of people enjoyed on that day the privilege of seeing

the national observatory. These annual gatherings are happily

still continued, and the first Saturday in June is known to be

the occasion of one of the most interesting reunions of scientific

men which takes place in the course of the year.

 

Airy’s scientific work was, however, by no means confined to the

observatory. He interested himself largely in expeditions for the

observation of eclipses and in projects for the measurement of

arcs on the earth. He devoted much attention to the collection of

magnetic observations from various parts of the world. Especially

will it be remembered that the circumstances of the transits of

Venus, which occurred in 1874 and in 1882, were investigated by

him, and under his guidance expeditions were sent forth to observe

the transits from those localities in remote parts of the earth

where observations most suitable for the determination of

the sun’s distance from the earth could be obtained. The

Astronomer Royal also studied tidal phenomena, and he rendered

great service to the country in the restoration of the standards

of length and weight which had been destroyed in the great fire at

the House of Parliament in October, 1834. In the most practical

scientific matters his advice was often sought, and was

as cheerfully rendered. Now we find him engaged in an

investigation of the irregularities of the compass in iron ships,

with a view to remedying its defects; now we find him reporting on

the best gauge for railways. Among the most generally useful

developments of the observatory must be mentioned the telegraphic

method for the distribution of exact time. By arrangement with

the Post Office, the astronomers at Greenwich despatch each

morning a signal from the observatory to London at ten o’clock

precisely. By special apparatus, this signal is thence

distributed automatically over the country, so as to enable the

time to be known everywhere accurately to a single second. It was

part of the same system that a time ball should be dropped daily

at one o’clock at Deal, as well as at other places, for the

purpose of enabling ship’s chronometers to be regulated.

 

Airy’s writings were most voluminous, and no fewer than forty-eight memoirs by him are mentioned in the “Catalogue of Scientific

Memoirs,” published by the Royal Society up to the year 1873,

and this only included ten years out of an entire life of most

extraordinary activity. Many other subjects besides those of a

purely scientific character from time to time engaged his

attention. He wrote, for instance, a very interesting treatise on

the Roman invasion of Britain, especially with a view of

determining the port from which Caesar set forth from Gaul, and

the point at which he landed on the British coast. Airy was

doubtless led to this investigation by his study of the tidal

phenomena in the Straits of Dover. Perhaps the Astronomer Royal

is best known to the general reading public by his excellent

lectures on astronomy, delivered at the Ipswich Museum in 1848.

This book has passed through many editions, and it gives a most

admirable account of the manner in which the fundamental problems

in astronomy have to be attacked.

 

As years rolled by almost every honour and distinction that

could be conferred upon a scientific man was awarded to Sir George

Airy. He was, indeed, the recipient of other honours not often

awarded for scientific distinction. Among these we may mention

that in 1875 he received the freedom of the City of London, “as a

recognition of his indefatigable labours in astronomy, and of his

eminent services in the advancement of practical science, whereby

he has so materially benefited the cause of commerce and

civilisation.”

 

Until his eightieth year Airy continued to discharge his labours

at Greenwich with unflagging energy. At last, on August 15th,

1881, he resigned the office which he had held so long with such

distinction to himself and such benefit to his country. He had

married in 1830 the daughter of the Rev. Richard Smith, of

Edensor. Lady Airy died in 1875, and three sons and three

daughters survived him. One daughter is the wife of Dr. Routh, of

Cambridge, and his other daughters were the constant companions of

their father during the declining years of his life. Up to the

age of ninety he enjoyed perfect physical health, but an

accidental fall which then occurred was attended with serious

results. He died on Saturday, January 2nd, 1892, and was buried in

the churchyard at Playford.

 

HAMILTON.

 

William Rowan Hamilton was born at midnight between the 3rd and

4th of August, 1805, at Dublin, in the house which was then 29,

but subsequently 36, Dominick Street. His father, Archibald

Hamilton, was a solicitor, and William was the fourth of a family

of nine. With reference to his descent, it may be sufficient to

notice that his ancestors appear to have been chiefly of gentle

Irish families, but that his maternal grandmother was of Scottish

birth. When he was about a year old, his father and mother

decided to hand over the education of the child to his uncle,

James Hamilton, a clergyman of Trim, in County Meath. James

Hamilton’s sister, Sydney, resided with him, and it was in their

home that the days of William’s childhood were passed.

 

In Mr. Graves’ “Life of Sir William Rowan Hamilton” a series

of letters will be found, in which Aunt Sydney details the

progress of the boy to his mother in Dublin. Probably there is no

record of an infant prodigy more extraordinary than that which

these letters contain. At three years old his aunt assured the

mother that William is “a hopeful blade,” but at that time it

was his physical vigour to which she apparently referred; for the

proofs of his capacity, which she adduces, related to his prowess

in making boys older than himself fly before him. In the second

letter, a month later, we hear that William is brought in to read

the Bible for the purpose of putting to shame other boys double

his age who could not read nearly so well. Uncle James appears to

have taken much pains with William’s schooling, but his aunt said

that “how he picks up everything is astonishing, for he never

stops playing and jumping about.” When he was four years and three

months old, we hear that he went out to dine at the vicar’s, and

amused the company by reading for them equally well whether the

book was turned upside down or held in any other fashion. His

aunt assures the mother that ” Willie is a most sensible little

creature, but at the same time has a great deal of roguery.” At

four years and five months old he came up to pay his mother a

visit in town, and she writes to her sister a description of the

boy;-

 

“His reciting is astonishing, and his clear and accurate

knowledge of geography is beyond belief; he even draws the

countries with a pencil on paper, and will cut them out,

though not perfectly accurate, yet so well that a anybody

knowing the countries could not mistake them; but, you will

think this nothing when I tell you that he reads Latin, Greek,

and Hebrew.”

 

Aunt Sydney recorded that the moment Willie got back to Trim he

was desirous of at once resuming his former pursuits. He would

not eat his breakfast till his uncle had heard him his Hebrew,

and he comments on the importance of proper pronunciation. At

five he was taken to see a friend, to whom he repeated long

passages from Dryden. A gentleman present, who was not

unnaturally sceptical about Willie’s attainments, desired to

test him in Greek, and took down a copy of Homer which happened

to have the contracted type, and to his amazement Willie went on

with the greatest ease. At six years and nine months he was

translating Homer and Virgil; a year later his uncle tells us

that William finds so little difficulty in learning French and

Italian, that he wishes to read Homer in French. He is

enraptured with the Iliad, and carries it about with him,

repeating from it whatever particularly pleases him. At eight

years and one month the boy was one of a party who visited

the Scalp in the Dublin mountains, and he was so delighted

with the scenery that he forthwith delivered an oration in

Latin. At nine years and six months he is not satisfied until

he learns Sanscrit; three months later his thirst for the

Oriental languages is unabated, and at ten years and four months

he is studying Arabic and Persian. When nearly twelve he

prepared a manuscript ready for publication. It was a “Syriac

Grammar,” in Syriac letters and characters compiled from that of

Buxtorf, by William Hamilton, Esq., of Dublin and Trim. When he

was fourteen, the Persian ambassador,