THE OBSERVATORY, DUNSINK.
Provost Baldwin held absolute sway in this University for forty-one
years. His memory is well preserved here. The Bursar still
dispenses the satisfactory revenues which Baldwin left to the
College. None of us ever can forget the marble angels round the
figure of the dying Provost on which we used to gaze during the
pangs of the Examination Hall.
Baldwin died in 1758, and was succeeded by Francis Andrews,
a Fellow of seventeen years’ standing. As to the scholastic
acquirements of Andrews, all I can find is a statement that he was
complimented by the polite Professors of Padua on the elegance
and purity with which he discoursed to them in Latin. Andrews was
also reputed to be a skilful lawyer. He was certainly a Privy
Councillor and a prominent member of the Irish House of Commons,
and his social qualities were excellent. Perhaps it was Baldwin’s
example that stimulated a desire in Andrews to become a benefactor
to his College. He accordingly bequeathed a sum of £3,000 and an
annual income of £250 wherewith to build and endow an Astronomical
Observatory in the University. The figures just stated ought to
be qualified by the words of cautious Ussher (afterwards the
first Professor of Astronomy), that “this money was to arise from
an accumulation of a part of his property, to commence upon a
particular contingency happening in his family.” The astronomical
endowment was soon in jeopardy by litigation. Andrews thought he
had provided for his relations by leaving to them certain leasehold
interests connected with the Provost’s estate. The law courts,
however, held that these interests were not at the disposal of
the testator, and handed them over to Hely Hutchinson, the next
Provost. The disappointed relations then petitioned the Irish
Parliament to redress this grievance by transferring to them
the monies designed by Andrews for the Observatory. It would
not be right, they contended, that the kindly intentions of the
late Provost towards his kindred should be frustrated for the
sake of maintaining what they described as “a purely ornamental
institution.” The authorities of the College protested against this
claim. Counsel were heard, and a Committee of the House made a
report declaring the situation of the relations to be a hard one.
Accordingly, a compromise was made, and the dispute terminated.
The selection of a site for the new Astronomical Observatory was
made by the Board of Trinity College. The beautiful neighbourhood
of Dublin offered a choice of excellent localities. On the north
side of the Liffey an Observatory could have been admirably placed,
either on the remarkable promontory of Howth or on the elevation
of which Dunsink is the summit. On the south side of Dublin there
are several eminences that would have been suitable: the breezy
heaths at Foxrock combine all necessary conditions; the obelisk
hill at Killiney would have given one of the most picturesque sites
for an Observatory in the world; while near Delgany two or three
other good situations could be mentioned. But the Board of those
pre-railway days was naturally guided by the question of proximity.
Dunsink was accordingly chosen as the most suitable site within the
distance of a reasonable walk from Trinity College.
The northern boundary of the Phoenix Park approaches the little
river Tolka, which winds through a succession of delightful bits
of sylvan scenery, such as may be found in the wide demesne of
Abbotstown and the classic shades of Glasnevin. From the banks of
the Tolka, on the opposite side of the park, the pastures ascend
in a gentle slope to culminate at Dunsink, where at a distance of
half-a-mile from the stream, of four miles from Dublin, and at
a height of 300 feet above the sea, now stands the Observatory.
From the commanding position of Dunsink a magnificent view is
obtained. To the east the sea is visible, while the southern
prospect over the valley of the Liffey is bounded by a range of
hills and mountains extending from Killiney to Bray Head, thence to
the Little Sugar Loaf, the Two Rock and the Three Rock Mountains,
over the flank of which the summit of the Great Sugar Loaf is just
perceptible. Directly in front opens the fine valley of Glenasmole,
with Kippure Mountain, while the range can be followed to its
western extremity. The climate of Dunsink is well suited for
astronomical observation. No doubt here, as elsewhere in Ireland,
clouds are abundant, but mists or haze are comparatively unusual,
and fogs are almost unknown.
[Illustration: DUNSINK OBSERVATORY.]
The legal formalities to be observed in assuming occupation
exacted a delay of many months: accordingly, it was not until
the 10th December, 1782, that a contract could be made with Mr.
Graham Moyers for the erection of a meridian room and a dome for
an Equatorial, in conjunction with a becoming residence for the
Astronomer. Before the work was commenced at Dunsink, the Board
thought it expedient to appoint the first Professor of Astronomy.
They met for this purpose on the 22nd January, 1783, and chose
the Reverend Henry Ussher, a Senior Fellow of Trinity College,
Dublin The wisdom of the appointment was immediately shown by the
assiduity with which Ussher engaged in founding the Observatory.
In three years he had erected the buildings and equipped them with
instruments, several of which were of his own invention. On the
19th of February, 1785, a special grant of £200 was made by the
Board to Dr. Ussher as some recompense for his labours. It happened
that the Observatory was not the only scientific institution which
came into being in Ireland at this period: the newly-kindled
ardour for the pursuit of knowledge led, at the same time, to the
foundation of the Royal Irish Academy. By a fitting coincidence,
the first memoir published in the Transactions of the Royal Irish
Academy was by the first Andrews Professor of Astronomy. It was
read on the 13th of June, 1785, and bore the title, “Account of
the Observatory belonging to Trinity College,” by the Reverend
H. Ussher, D.D., M.R.I.A., F.R.S. This communication shows the
extensive design that had been originally intended for Dunsink,
only a part of which was, however, carried out. For instance, two
long corridors running north and south from the central edifice,
which are figured in the paper, never developed into bricks
and mortar. We are not told why the original scheme had to be
contracted; but perhaps the reason may be not unconnected with a
remark of Ussher’s, that the College had already advanced from
its own funds a sum considerably exceeding the original bequest.
A picture of the building, showing also the dome for the South
Equatorial, which was erected many years later, is given on page
133.
Ussher died in 1790. During his brief career at the Observatory,
he observed eclipses, and is stated to have done other scientific
work. The minutes of the Board declare that the infant institution
had already obtained celebrity by his labours, and they urge the
claims of his widow to a pension on the ground that the disease
from which he died had been contracted by his nightly vigils. The
Board also promised a grant of fifty guineas as a help to bring out
Dr. Ussher’s sermons. They advanced twenty guineas to his widow
towards the publication of his astronomical papers. They ordered
his bust to be executed for the Observatory, and offered “The Death
of Ussher” as the subject of a prize essay; but, so far as I can
find, neither the sermons nor the papers, neither the bust nor the
prize essay, ever came into being.
There was keen competition for the Chair of Astronomy, which
the death of Ussher vacated. The two candidates were Rev. John
Brinkley, of Caius College, Cambridge, a Senior Wrangler (born at
Woodbridge, Suffolk, in 1763), and Mr. Stack, Fellow of Trinity
College, Dublin, and author of a book on Optics. A majority of the
Board at first supported Stack, while Provost Hely Hutchinson and
one or two others supported Brinkley. In those days the Provost
had a veto at elections, so that ultimately Stack was withdrawn,
and Brinkley was elected. This took place on the 11th December,
1790. The national press of the day commented on the preference
shown to the young Englishman, Brinkley, over his Irish rival. An
animated controversy ensued. The Provost himself condescended to
enter the lists, and to vindicate his policy by a long letter in
the _Public Register or Freeman’s Journal_, of 21st December, 1790.
This letter was anonymous, but its authorship is obvious. It gives
the correspondence with Maskelyne and other eminent astronomers,
whose advice and guidance had been sought by the Provost. It also
contends that “the transactions of the Board ought not to be
canvassed in the newspapers.” For this reference, as well as for
much other information, I am indebted to my friend the Rev. John W.
Stubbs, D.D.
The next event in the history of the Observatory was the issue of
Letters Patent (32 Geo. III., A.D. 1792), in which it is recited
that “We grant and ordain that there shall be for ever hereafter
a Professor of Astronomy, on the foundation of Dr. Andrews, to be
called and known by the name of the Royal Astronomer of Ireland.”
The letters prescribe the various duties of the Astronomer, and
the mode of his election. They lay down regulations as to the
conduct of the astronomical work, and as to the choice of an
assistant. They direct that the Provost and Senior Fellows shall
make a thorough inspection of the Observatory once every year,
in June or July; and this duty was first undertaken on the 5th
of July, 1792. It will thus be noted that the date fixed for the
celebration of the Tercentenary of the University happens to be the
centenary of the first Visitation of the Observatory. The Visitors
on the first occasion were--A. Murray, Matthew Young, George
Hall, and John Barrett. They record that they find the buildings,
books, and instruments in good condition; but the chief feature in
this report, as well as in many which followed it, related to a
circumstance to which we have not yet referred.
In the original equipment of the Observatory, Ussher, with the
natural ambition of a founder, desired to place in it a telescope
of more magnificent proportions than could be found anywhere
else. The Board gave a spirited support to this enterprise,
and negotiations were entered into with the most eminent
instrument-maker of those days. This was Jesse Ramsden (1735-1800),
famous as the improver of the sextant, as the constructor of the
great Theodolite used by General Roy in the English Survey, and as
the inventor of the Dividing Engine for graduating astronomical
instruments. Ramsden had built for Sir George Schuckburgh the
largest and most perfect Equatorial ever attempted. He had
constructed mural quadrants for Padua and Verona, which elicited
the wonder of astronomers, when Dr. Maskelyne declared he could
detect no error in their graduation as large as two seconds and
a-half. But Ramsden maintained that even better results would be
obtained by superseding the entire quadrant by the circle. He
obtained the means of testing this prediction when he completed
a superb circle for Palermo of five feet diameter. Finding
his anticipations were realised, he desired to apply the same
principles on a still grander scale. Ramsden was in this mood when
he met with Dr. Ussher. The enthusiasm of the Astronomer and the
instrument-maker communicated itself to the Board, and a tremendous
circle, to be ten feet in diameter, was forthwith projected.
Projected, but never carried out. After Ramsden had to some extent
completed a ten-foot circle, he found such difficulties that he
tried a nine-foot, and this again he discarded for an eight-foot,
which was ultimately accomplished, though not entirely by himself.
Notwithstanding the contraction from the vast proportions
originally designed, the completed instrument must still be
regarded as a colossal piece of astronomical workmanship. Even at
this day I do not know that any other Observatory except Dunsink
can show a circle eight feet in diameter graduated all round.
I think it is Professor Piazzi Smyth who tells us how grateful
he was to find a large telescope he had ordered finished by the
opticians on the very day they had promised it. The day was
perfectly correct; it was only the year that was wrong. A somewhat
remarkable experience in this direction is chronicled by the early
reports of the Visitors to the Dunsink Observatory. I cannot find
the date on which the great circle was ordered from Ramsden, but it
is fixed with sufficient precision by an allusion in Ussher’s paper
to the Royal Irish Academy, which shows that by the 13th June,
1785, the order had been given, but that the abandonment of the
ten-foot scale had not then been contemplated. It was reasonable
that the Board should allow Ramsden ample time for the completion
of a work at once so elaborate and so novel. It could not have
been finished in a year, nor would there have been much reason for
complaint if the maker had found he required two or even three
years more.
Seven years gone, and still no telescope, was the condition in
which the Board found matters at their first Visitation in 1792.
They had, however, assurances from Ramsden that the instrument
would be completed within the year; but, alas for such promises!
another seven years rolled on, and in 1799 the place for the great
circle was still vacant at Dunsink. Ramsden had fallen into bad
health, and the Board considerately directed that “inquiries should
be made.” Next year there was still no progress, so the Board were
roused to threaten Ramsden with a suit at law; but the menace was
never executed, for the malady of the great optician grew worse,
and he died that year.
Affairs had now assumed a critical aspect, for the College had
advanced much money to Ramsden during these fifteen years, and the
instrument was still unfinished. An appeal was made by the Provost
to Dr. Maskelyne, the Astronomer-Royal of England, for his advice
and kindly offices in this emergency. Maskelyne responds--in terms
calculated to allay the anxiety of the Bursar--“Mr. Ramsden has
left property behind him, and the College can be in no danger of
losing both their money and the instrument.” The business of
Ramsden was then undertaken by Berge, who proceeded to finish the
great circle quite as deliberately as his predecessor. After four
years Berge promised the instrument in the following August, but it
did not come. Two years later (1806) the Professor complains that
he can get no answer from Berge. In 1807 it is stated that Berge
will send the telescope in a month. He did not; but in the next
year (1808), about twenty-three years after the great circle was
ordered, it was erected at Dunsink, where it is still to be seen.
The following circumstances have been authenticated by the
signatures of Provosts, Proctors, Bursars, and other College
dignitaries:--In 1793 the Board ordered two of the clocks at the
Observatory to be sent to Mr. Crosthwaite for repairs. Seven years
later, in 1800, Mr. Crosthwaite was asked if the clocks were ready.
This impatience was clearly unreasonable, for even in four years
more, 1804, we find the two clocks were still in hands. Two years
later, in 1806, the Board determined to take vigorous action by
asking the Bursar to call upon Crosthwaite. This evidently produced
some effect, for in the following year, 1807, the Professor had
no doubt that the clocks would be speedily returned. After eight
years more, in 1815, one of the clocks was still being repaired,
and so it was in 1816, which is the last record we have of these
interesting timepieces. Astronomers are, however, accustomed to
deal with such stupendous periods in their calculations, that even
the time taken to repair a clock seems but small in comparison.
The long tenure of the Chair of Astronomy by Brinkley is divided
into two nearly equal periods by the year in which the great circle
was erected. Brinkley was eighteen years waiting for his telescope,
and he had eighteen years more in which to use it. During the first
of these periods Brinkley devoted himself to mathematical research;
during the latter he became a celebrated astronomer. Brinkley’s
mathematical labours procured for their author some reputation as a
mathematician. They appear to be works of considerable mathematical
elegance, but not indicating any great power of original thought.
Perhaps it has been prejudicial to Brinkley’s fame in this
direction that he was immediately followed in his chair by so
mighty a genius as William Rowan Hamilton.
After the great circle had been at last erected, Brinkley was
able to begin his astronomical work in earnest. Nor was there
much time to lose. He was already 45 years old, a year older than
was Herschel when he commenced his immortal career at Slough.
Stimulated by the consciousness of having the command of an
instrument of unique perfection, Brinkley loftily attempted the
very highest class of astronomical research. He resolved to measure
anew with his own eye and with his own hand the constants of
aberration and of nutation. He also strove to solve that great
problem of the universe, the discovery of the distance of a fixed
star.
These were noble problems, and they were nobly attacked. But to
appraise with justice this work of Brinkley, done seventy years
ago, we must not apply to it the same criteria as we would think
right to apply to similar work were it done now. We do not any
longer use Brinkley’s constant of aberration, nor do we now think
that Brinkley’s determinations of the star-distances were reliable.
But, nevertheless, his investigations exercised a marked influence
on the progress of science: they stimulated the study of the
principles on which exact measurements were to be conducted.
Brinkley had another profession in addition to that of an
astronomer. He was a divine. When a man endeavours to pursue two
distinct occupations concurrently, it will be equally easy to
explain why his career should be successful, or why it should be
the reverse. If he succeeds, he will, of course, exemplify the
wisdom of having provided two strings to his bow. Should he fail,
it is, of course, because he has attempted to sit on two stools
at once. In Brinkley’s case, his two professions must be likened
to the two strings rather than to the two stools. It is true that
his practical experience of a clerical life was very slender. He
had made no attempt to combine the routine of a parish with his
labours in the Observatory. Nor do we associate a special eminence
in any department of religious work with his name. If, however, we
are to measure Brinkley’s merits as a divine by the ecclesiastical
preferment which he received, his services to theology must have
rivalled his services to astronomy. Having been raised step by step
in the church, he was at last appointed to the See of Cloyne in
1826 as the successor of Bishop Berkeley.
Now, though it was permissible for the Archdeacon to be also the
Andrews Professor, yet when the Archdeacon became a Bishop it
was understood that he should transfer his residence from the
Observatory to the Palace. The Chair of Astronomy accordingly
became vacant. Brinkley’s subsequent career seems to have been
devoted entirely to ecclesiastical matters, and for the last ten
years of his life he did not contribute a paper to any scientific
society. Arago, after a characteristic lament that Brinkley should
have forsaken the pursuit of Science for the temporal and spiritual
attractions of a Bishopric, pays a tribute to the conscientiousness
of the quondam astronomer:--
“A partir du jour ou il fut revêtu de l’episcopat, l’homme dont
toute la vie avait été consacrée jusque-là à la contemplation du
firmament et à la solution des questions sublimes qui recèlent
les mouvements des astres, divorca complétement avec ces douces,
avec ces entraînantes occupations, pour se livrer sans partage
aux devoirs de sa charge nouvelle, afin d’échapper, je suppose, à
la tentation, l’ex-Directeur de l’Observatoire Royal d’Irlande,
l’ex-Andrews Professor d’Astronomie de l’Université n’avait pas
même dans son palais la plus modeste lunette. On doit la révélation
de se fait presque incroyable, à l’indiscrétion d’une personne qui
s’étant trouvée chez l’évêque de Cloyne un jour d’éclipse de Lune,
eut le déplaisir, faute d’instruments, de ne pouvoir suivre la
marche du phénomène qu’avec ses yeux.”
The good Bishop died on the 13th September, 1835. He was buried in
the Chapel of Trinity College, and a fine monument to his memory
is a familiar object at the foot of the noble old staircase of the
library. The best memorial of Brinkley is his admirable book on the
_Elements of Plane Astronomy_. It passed through many editions in
his lifetime, and even at the present day the same work, revised
first by Dr. Luby and more recently by the Rev. Dr. Stubbs and Dr.
Brünnow, has a large and well-merited circulation.
On the 4th August, 1805, a few years before the great circle was
erected at the Observatory, William Rowan Hamilton was born in
No. 36, Dominick Street, Dublin. He was educated by his uncle,
the Rev. James Hamilton, at Trim, and his aunt, Jane Sidney
Hamilton. The astounding precocity of the child is thus described
by his biographer, Mr. Graves, to whose laborious and painstaking
execution of his great task I must here make my acknowledgments. Of
William Rowan Hamilton it is asserted that, “continuing a vigorous
child in spirits and playfulness, he was, at three years of age, a
superior reader of English and considerably advanced in arithmetic;
at four, a good geographer; at five, able to read and translate
Latin, Greek, and Hebrew, and loving to recite Dryden, Collins,
Milton, and Homer; at eight he has added Italian and French, and
given vent to his feelings in extemporised Latin; and before he is
ten he is a student of Arabic and Sanskrit. And all this knowledge
seems to have been acquired, not indeed without diligence, but
with perfect ease, and applied, as occasion arose, with practical
judgment and tact.”[107]
When Hamilton was seventeen years old (1822), he had written
original mathematical papers, and with two of these--entitled
respectively, “Osculating Parabola to Curves of Double Curvature,”
and “On Contacts between Algebraic Curves and Surfaces”--he paid
a visit to Dr. Brinkley at the Observatory. The Royal Astronomer
was impressed by their value, and desired to see them in a more
developed form. Thus originated an acquaintance between the
scientific veteran, soon to be a Bishop, and the brilliant lad
about to enter college.
After Brinkley had been appointed Bishop of Cloyne in 1826,
Hamilton was immediately mentioned as his probable successor. Mr.
Graves, to whom I am indebted for these particulars, assures us
that Hamilton never put himself forward until a week before the
election, when he received an urgent letter from his tutor, Mr.
Boyton, to say that the Board were favourably disposed towards him.
On the 16th June, 1827, the undergraduate of twenty-two, William
Rowan Hamilton, was unanimously elected to the Chair of Astronomy.
Nor was he without formidable competitors. Airy was a candidate,
and so were some of the Fellows of Trinity College; yet a general
approval, almost unanimous, ratified the choice of the Board.
We say almost unanimous, because there was at least one weighty
opinion on the other side. Bishop Brinkley thought that Hamilton
had acted imprudently in accepting the post, and that it would have
been wiser for him to have sought a Fellowship. With Hamilton’s
life before us, we can now see that the Bishop was not right.
The leisure and the seclusion of the Observatory were necessary
conditions for Hamilton’s colossal labours. After his election to
the Chair of Astronomy, Hamilton proceeded to his degree in the
usual manner; but before doing so, he had, as an undergraduate,
to perform the somewhat anomalous duty of examining graduates in
the higher branches of mathematics for Bishop Law’s mathematical
premium.
The history of Dunsink Observatory for the next 38 years may be
epitomised in a single word--Quaternions. It will be unnecessary to
refer in any detail to the great career of our great mathematician.
The early promise of the marvellous child and the brilliant career
of the unparalleled student soon bore fruit in the congenial
atmosphere of the Observatory. Conical Refraction, the Theory of
Rays, the general method of Dynamics--any one of these researches
would have conferred fame of which the greatest mathematician might
have been proud, but with Hamilton these were merely incidental to
the great work of his life. With huge industry he cultivated his
powers, he wrought his mighty system of Quaternions, and found in
it a weapon adequate to deal with the most profound mathematical
problems of nature. It is not Hamilton’s fault if others have found
that to wield this sword of a giant the arm of the giant is also
necessary. Most of us feel satisfied if we know enough to be able
to reverence the two awful volumes which every mathematician likes
to see on his shelves, and which he generally leaves there.
So great a personality as Hamilton has naturally gathered around
itself much biographical interest. The intimacy between Hamilton
and Wordsworth has given many interesting pages to Mr. Graves’
book, and how intimate the friendship became may be conjectured
from the account of their first meeting. We are told how Hamilton
walked back with Wordsworth to see him home after a delightful
evening, and how Wordsworth then turned to see Hamilton back, and
how the process was repeated I know not how often. It appears that
Hamilton submitted his poetic effusions to his friend, and they
were returned with gentle criticism, though with an occasional
admission by Wordsworth that the mathematician’s verses possessed
genuine feeling. Then there is the visit of Wordsworth to Dunsink,
where to this day a beautiful shady walk bears his name. Hamilton
enjoyed the privilege of intimacy with many cultivated intellects.
He knew Coleridge; with Sir John Herschel he was in frequent
communication; and he had many lady correspondents, including
Maria Edgeworth. The bulk of Hamilton’s scientific correspondence
was with the late Professor De Morgan, a man whose intellectual
endowments were of such a different type to those of Hamilton,
that, except in being both mathematicians, they had but little in
common. On the death of Hamilton, De Morgan writes to Sir John
Herschel (Sept. 13, 1865):--
“W. R. Hamilton was an intimate friend whom I spoke to once
in my life--at Babbage’s about 1830; but for 30 years we have
corresponded. I _saw_ him a second time at the dinner you got at
the Freemason’s when you came from the Cape, but I could not get
near enough to speak.”[108]
The Observatory had the usual equipment of a transit instrument, a
circle, and an equatorial, but no further additions were made to
the instruments during the long sojourn of Hamilton. Observations
were made by the assistant, Mr. Thomson, who, after a life passed
in the service, retired in 1874, and lived a few years to enjoy
the pension conferred on him by the Board. Just before Sir W.
Hamilton’s death an important donation was received by the College.
I shall here mention the circumstances under which it was made.
The particulars were related to me partly by the donor himself,
and partly by the late Earl of Rosse. The chief incidents in the
narrative may be found in the life of De Morgan[109] to which I
have already referred.
Sir James South was a medical man who acquired considerable wealth
early in life, and then devoted himself with great assiduity to
astronomy. He became an expert observer, and in conjunction with
Sir John Herschel formed a series of double star measures that
obtained much fame. Honours flowed in upon South; he received a
pension and a knighthood; and he prepared for further astronomical
work. His first care was to procure a superior telescope, and from
Cauchoix, a French optician of renown, he procured an object-glass
12 inches in diameter, and possessing great optical perfection.
For this lens, or rather pair of lenses, he paid either £800 or
£1,000. South returned with this prize to his observatory at
Campden Hill, Kensington, and commenced to have the mounting
executed in a manner befitting the optical excellence of the lens.
Brunel designed the revolving dome; it was made of mahogany, and
cost, I believe, £2,000; and inside this building the eminent firm
of Troughton & Simms were called upon to erect the telescope. But
sad troubles followed, of which an entertaining account is given in
De Morgan’s Life (p. 61), and the mounting was a dismal failure.
Sir James South, at all events in the later part of his career,
dearly loved a fray. He commissioned a friend to bear a hostile
message to a distinguished scientific contemporary. The duel never
came off. Perhaps, even if it had, the results might not have been
sanguinary, for it had been suggested that the two astronomers
would, of course, have been placed at telescopic distances apart.
But to those to whom he was attached his loyalty and devotion
were unbounded; his purse and his influence were alike at their
disposal. To these characteristics of South we owe the great
equatorial telescope now at Dunsink Observatory.
[Illustration: SOUTH EQUATORIAL, DUNSINK.]
The precious object-glass remained in his possession for about
thirty years, until such time as the late Earl of Rosse was
installed as Chancellor of the University. The Earl was one of Sir
James’ warm friends, and he celebrated the occasion by presenting
the great object-glass to the University of Dublin. The date of the
gift is 17th February, 1863.
It was thus only a few years before Sir W. R. Hamilton’s death
that Dunsink Observatory possessed a really fine objective; but
it was only an objective, it was not a telescope. The engrossing
labours of Sir W. R. Hamilton’s mathematical work, his advancing
years, and his declining health, did not permit him to undertake
the arduous labour of its erection. Sir James South found in this
a sad grievance. I have heard him denounce this inaction with that
vigorous language which he was accustomed to use. He had even
offered to contribute liberally to the expenses of mounting, if the
College authorities would put it in hands. It was not, however,
until Sir W. R. Hamilton’s successor was appointed (1865) that the
work was done. South lived just long enough to know that the great
instrument was at last being erected. A view of the instrument,
named the South Equatorial, after the donor, is shown in the
adjoining illustration.
The successor of Sir William Rowan Hamilton as Andrews Professor
of Astronomy was Dr. Francis Brünnow. He was a German by birth,
who had distinguished himself by various astronomical researches,
and by an excellent work on Practical Astronomy. He had previously
occupied the Chair of Astronomy at the University of Michigan.
When Brünnow came to Dunsink, his first care was the mounting
of the great South Equatorial. A building was erected on the
lawn, surmounted by a dome, and fitted with revolving machinery
by Messrs. Grubb, who also constructed the tube and stand. A
micrometer, from the Berlin firm of Messrs. Pistor & Martin, was
added, and thus the South object-glass, forty years after it was
made, came into actual use.
Dr. Brünnow devoted himself chiefly to the investigation of the
Parallax of Stars. In this he was, indeed, following the traditions
of the Observatory as laid down by Brinkley. Brünnow published two
parts of his researches on this difficult subject. These papers are
now regarded as a classical authority in this branch of astronomy.
The pains which he took to eliminate error, and the consummate
manner in which he has discussed his results, show him to have been
both a skilful observer and an ingenious computer.
The fundamental equipment of the modern Observatory must include
an equatorial and a meridian circle. Dunsink was now provided with
the former, but there was no meridian circle. The great Ramsden
instrument had become obsolete. The old transit had also seen more
than half-a-century of service, and could not be relied on for
accurate work. A splendid meridian circle was therefore ordered,
by the liberality of the Board, from Messrs. Pistor & Martin,
of Berlin. It was erected in 1872-1873, at a cost of £800. The
aperture of this instrument is 6·4 inches and the length is 8 feet.
The circles are divided to two-minute spaces, and read by eight
microscopes, four on each side. The instrument can be reversed, and
has north and south collimators. The Meridian Room and the fine
instrument just described are shown in the subjoined illustration.
[Illustration: MERIDIAN ROOM, DUNSINK.]
In 1874 Dr. Brünnow resigned, and was succeeded by the present
writer; and about the same time Dr. Ralph Copeland was appointed
assistant. In the following year Dr. Copeland went to the Earl
of Crawford’s Observatory at Dunecht, and he now fills the
distinguished position of Royal Astronomer of Scotland. Dr.
Copeland was succeeded as assistant at Dunsink by Mr. C. E. Burton.
Failing health caused Mr. Burton’s resignation in 1878, and Dr.
J. L. E. Dreyer then came to Dunsink, where he remained till the
death of the late Dr. Romney Robinson in 1882 created a vacancy
in the post of Astronomer at Armagh, to which Dr. Dreyer was
then appointed. His place at Dunsink was filled by Dr. Arthur A.
Rambaut, the present assistant.
Among the additions made to the Observatory under my direction
may be mentioned an electric chronograph for recording transits.
A time service has also been in operation for many years, by
which the standard mean time clock in the Observatory controls,
on Jones’ system, the Front clock and the Board-room clock in the
Port and Docks Office, Westmoreland Street, Dublin. The ball falls
at this office at 1 p.m., Greenwich time, and the fact of falling
reports itself automatically at Dunsink, while the Front clock
reports itself at Dunsink every minute. But the chief addition to
the Observatory in late years is the superb reflecting telescope
for photographic purposes, which is the gift of Isaac Roberts,
Esq., F.R.S., of Crowborough, Sussex. This instrument has been
established in the small dome on the top of the Observatory.
The last chronicle of Dunsink that it may be necessary here to
mention is that Sir Robert Ball was appointed, on 20th February,
1892, to succeed Professor J. Couch Adams as Lowndean Professor of
Astronomy in the University of Cambridge.
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FOOTNOTES:
[107] Graves’ _Life of Hamilton_, vol. i., p. 46.
[108] Life of De Morgan, by his wife, p. 333.
[109] _Ibid._
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