<h3><SPAN name="HAMILTON" id="HAMILTON"></SPAN>HAMILTON.</h3>
<p>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.</p>
<p>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;—</p>
<p>"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."</p>
<p>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, Mirza Abul Hassan Khan, paid a
visit to Dublin, and, as a practical exercise in his Oriental
languages, the young scholar addressed to his Excellency a letter in
Persian; a translation of which production is given by Mr. Graves.
When William was fourteen he had the misfortune to lose his father;
and he had lost his mother two years previously. The boy and his
three sisters were kindly provided for by different members of the
family on both sides.</p>
<p>It was when William was about fifteen that his attention began to be
turned towards scientific subjects. These were at first regarded
rather as a relaxation from the linguistic studies with which he had
been so largely occupied. On November 22nd, 1820, he notes in his
journal that he had begun Newton's "Principia": he commenced also the
study of astronomy by observing eclipses, occultations, and similar
phenomena. When he was sixteen we learn that he had read conic
sections, and that he was engaged in the study of pendulums. After
an attack of illness, he was moved for change to Dublin, and in May,
1822, we find him reading the differential calculus and Laplace's
"Mecanique Celeste." He criticises an important part of Laplace's
work relative to the demonstration of the parallelogram of forces. In
this same year appeared the first gushes of those poems which
afterwards flowed in torrents.</p>
<p>His somewhat discursive studies had, however, now to give place to a
more definite course of reading in preparation for entrance to the
University of Dublin. The tutor under whom he entered, Charles
Boyton, was himself a distinguished man, but he frankly told the
young William that he could be of little use to him as a tutor, for
his pupil was quite as fit to be his tutor. Eliza Hamilton, by whom
this is recorded, adds, "But there is one thing which Boyton would
promise to be to him, and that was a FRIEND; and that one proof he
would give of this should be that, if ever he saw William beginning
to be UPSET by the sensation he would excite, and the notice he would
attract, he would tell him of it." At the beginning of his college
career he distanced all his competitors in every intellectual
pursuit. At his first term examination in the University he was
first in Classics and first in Mathematics, while he received the
Chancellor's prize for a poem on the Ionian Islands, and another for
his poem on Eustace de St. Pierre.</p>
<p>There is abundant testimony that Hamilton had "a heart for friendship
formed." Among the warmest of the friends whom he made in these
early days was the gifted Maria Edgeworth, who writes to her sister
about "young Mr. Hamilton, an admirable Crichton of eighteen, a real
prodigy of talents, who Dr. Brinkley says may be a second Newton,
quiet, gentle, and simple." His sister Eliza, to whom he was
affectionately attached, writes to him in 1824:—</p>
<p>"I had been drawing pictures of you in my mind in your study at
Cumberland Street with 'Xenophon,' &c., on the table, and you, with
your most awfully sublime face of thought, now sitting down, and now
walking about, at times rubbing your hands with an air of
satisfaction, and at times bursting forth into some very heroical
strain of poetry in an unknown language, and in your own internal
solemn ventriloquist-like voice, when you address yourself to the
silence and solitude of your own room, and indeed, at times, even
when your mysterious poetical addresses are not quite unheard."</p>
<p>This letter is quoted because it refers to a circumstance which all
who ever met with Hamilton, even in his latest years, will remember.
He was endowed with two distinct voices, one a high treble, the other
a deep bass, and he alternately employed these voices not only in
ordinary conversation, but when he was delivering an address on the
profundities of Quaternions to the Royal Irish Academy, or on
similar occasions. His friends had long grown so familiar with this
peculiarity that they were sometimes rather surprised to find how
ludicrous it appeared to strangers.</p>
<p>Hamilton was fortunate in finding, while still at a very early age, a
career open before him which was worthy of his talents. He had not
ceased to be an undergraduate before he was called to fill an
illustrious chair in his university. The circumstances are briefly
as follows.</p>
<p>We have already mentioned that, in 1826, Brinkley was appointed
Bishop of Cloyne, and the professorship of astronomy thereupon became
vacant. Such was Hamilton's conspicuous eminence that,
notwithstanding he was still an undergraduate, and had only just
completed his twenty-first year, he was immediately thought of as a
suitable successor to the chair. Indeed, so remarkable were his
talents in almost every direction that had the vacancy been in the
professorship of classics or of mathematics, of English literature or
of metaphysics, of modern or of Oriental languages, it seems
difficult to suppose that he would not have occurred to every one as
a possible successor. The chief ground, however, on which the
friends of Hamilton urged his appointment was the earnest of original
power which he had already shown in a research on the theory of
Systems of Rays. This profound work created a new branch of optics,
and led a few years later to a superb discovery, by which the fame of
its author became world-wide.</p>
<p>At first Hamilton thought it would be presumption for him to apply
for so exalted a position; he accordingly retired to the country, and
resumed his studies for his degree. Other eminent candidates came
forward, among them some from Cambridge, and a few of the Fellows
from Trinity College, Dublin, also sent in their claims. It was not
until Hamilton received an urgent letter from his tutor Boyton, in
which he was assured of the favourable disposition of the Board
towards his candidature, that he consented to come forward, and on
June 16th, 1827, he was unanimously chosen to succeed the Bishop of
Cloyne as Professor of Astronomy in the University. The appointment
met with almost universal approval. It should, however, be noted
that Brinkley, whom Hamilton succeeded, did not concur in the general
sentiment. No one could have formed a higher opinion than he had
done of Hamilton's transcendent powers; indeed, it was on that very
ground that he seemed to view the appointment with disapprobation.
He considered that it would have been wiser for Hamilton to have
obtained a Fellowship, in which capacity he would have been able to
exercise a greater freedom in his choice of intellectual pursuits.
The bishop seems to have thought, and not without reason, that
Hamilton's genius would rather recoil from much of the routine work
of an astronomical establishment. Now that Hamilton's whole life is
before us, it is easy to see that the bishop was entirely wrong. It
is quite true that Hamilton never became a skilled astronomical
observer; but the seclusion of the observatory was eminently
favourable to those gigantic labours to which his life was devoted,
and which have shed so much lustre, not only on Hamilton himself, but
also on his University and his country.</p>
<p>In his early years at Dunsink, Hamilton did make some attempts at a
practical use of the telescopes, but he possessed no natural aptitude
for such work, while exposure which it involved seems to have acted
injuriously on his health. He, therefore, gradually allowed his
attention to be devoted to those mathematical researches in which he
had already given such promise of distinction. Although it was in
pure mathematics that he ultimately won his greatest fame, yet he
always maintained and maintained with justice, that he had ample
claims to the title of an astronomer. In his later years he set
forth this position himself in a rather striking manner. De Morgan
had written commending to Hamilton's notice Grant's "History of
Physical Astronomy." After becoming acquainted with the book,
Hamilton writes to his friend as follows:—</p>
<p>"The book is very valuable, and very creditable to its composer. But
your humble servant may be pardoned if he finds himself somewhat
amused at the title, 'History of Physical Astronomy from the Earliest
Ages to the Middle of the Nineteenth Century,' when he fails to
observe any notice of the discoveries of Sir W. R. Hamilton in the
theory of the 'Dynamics of the Heavens.'"</p>
<p>The intimacy between the two correspondents will account for the tone
of this letter; and, indeed, Hamilton supplies in the lines which
follow ample grounds for his complaint. He tells how Jacobi spoke of
him in Manchester in 1842 as "le Lagrange de votre pays," and how
Donkin had said that, "The Analytical Theory of Dynamics as it exists
at present is due mainly to the labours of La Grange Poisson,
Sir W. R. Hamilton, and Jacobi, whose researches on this subject
present a series of discoveries hardly paralleled for their elegance
and importance in any other branch of mathematics." In the same
letter Hamilton also alludes to the success which had attended the
applications of his methods in other hands than his own to the
elucidation of the difficult subject of Planetary Perturbations.
Even had his contributions to science amounted to no more than these
discoveries, his tenure of the chair would have been an illustrious
one. It happens, however, that in the gigantic mass of his
intellectual work these researches, though intrinsically of such
importance, assume what might almost be described as a relative
insignificance.</p>
<p>The most famous achievement of Hamilton's earlier years at the
observatory was the discovery of conical refraction. This was one of
those rare events in the history of science, in which a sagacious
calculation has predicted a result of an almost startling character,
subsequently confirmed by observation. At once this conferred on the
young professor a world-wide renown. Indeed, though he was still
only twenty-seven, he had already lived through an amount of
intellectual activity which would have been remarkable for a man of
threescore and ten.</p>
<p>Simultaneously with his growth in fame came the growth of his several
friendships. There were, in the first place, his scientific
friendships with Herschel, Robinson, and many others with whom he had
copious correspondence. In the excellent biography to which I have
referred, Hamilton's correspondence with Coleridge may be read, as
can also the letters to his lady correspondents, among them being
Maria Edgeworth, Lady Dunraven, and Lady Campbell. Many of these
sheets relate to literary matters, but they are largely intermingled
With genial pleasantry, and serve at all events to show the affection
and esteem with which he was regarded by all who had the privilege of
knowing him. There are also the letters to the sisters whom he
adored, letters brimming over with such exalted sentiment, that most
ordinary sisters would be tempted to receive them with a smile in the
excessively improbable event of their still more ordinary brothers
attempting to pen such effusions. There are also indications of
letters to and from other young ladies who from time to time were the
objects of Hamilton's tender admiration. We use the plural
advisedly, for, as Mr. Graves has set forth, Hamilton's love affairs
pursued a rather troubled course. The attention which he lavished on
one or two fair ones was not reciprocated, and even the intense
charms of mathematical discovery could not assuage the pangs which
the disappointed lover experienced. At last he reached the haven of
matrimony in 1833, when he was married to Miss Bayly. Of his married
life Hamilton said, many years later to De Morgan, that it was as
happy as he expected, and happier than he deserved. He had two sons,
William and Archibald, and one daughter, Helen, who became the wife
of Archdeacon O'Regan.</p>
<p><SPAN name="rowan_hamilton" id="rowan_hamilton"></SPAN></p>
<div class="figcenter"> <SPAN href="images/ill_rowan_hamilton.jpg"> <ANTIMG src="images/ill_rowan_hamilton_sml.jpg" width-obs="418" height-obs="479" alt="SIR W. ROWAN HAMILTON." title="" /></SPAN> <span class="caption">SIR W. ROWAN HAMILTON.</span></div>
<p>The most remarkable of Hamilton's friendships in his early years was
unquestionably that with Wordsworth. It commenced with Hamilton's
visit to Keswick; and on the first evening, when the poet met the
young mathematician, an incident occurred which showed the mutual
interest that was aroused. Hamilton thus describes it in a letter to
his sister Eliza:—</p>
<p>"He (Wordsworth) walked back with our party as far as their lodge,
and then, on our bidding Mrs. Harrison good-night, I offered to walk
back with him while my party proceeded to the hotel. This offer he
accepted, and our conversation had become so interesting that when we
had arrived at his home, a distance of about a mile, he proposed to
walk back with me on my way to Ambleside, a proposal which you may be
sure I did not reject; so far from it that when he came to turn once
more towards his home I also turned once more along with him. It was
very late when I reached the hotel after all this walking."</p>
<p>Hamilton also submitted to Wordsworth an original poem, entitled
"It Haunts me Yet." The reply of Wordsworth is worth repeating:—</p>
<p>"With a safe conscience I can assure you that, in my judgment, your
verses are animated with the poetic spirit, as they are evidently the
product of strong feeling. The sixth and seventh stanzas affected me
much, even to the dimming of my eyes and faltering of my voice while
I was reading them aloud. Having said this, I have said enough. Now
for the per contra. You will not, I am sure, be hurt when I tell you
that the workmanship (what else could be expected from so young a
writer?) is not what it ought to be. . .</p>
<p>"My household desire to be remembered to you in no formal way.
Seldom have I parted—never, I was going to say—with one whom after
so short an acquaintance I lost sight of with more regret. I trust
we shall meet again."</p>
<p>The further affectionate intercourse between Hamilton and Wordsworth
is fully set forth, and to Hamilton's latest years a recollection of
his "Rydal hours" was carefully treasured and frequently referred
to. Wordsworth visited Hamilton at the observatory, where a
beautiful shady path in the garden is to the present day spoken of as
"Wordsworth's Walk."</p>
<p>It was the practice of Hamilton to produce a sonnet on almost every
occasion which admitted of poetical treatment, and it was his delight
to communicate his verses to his friends all round. When Whewell was
producing his "Bridgewater Treatises," he writes to Hamilton in
1833:—</p>
<p>"Your sonnet which you showed me expressed much better than I could
express it the feeling with which I tried to write this book, and I
once intended to ask your permission to prefix the sonnet to my book,
but my friends persuaded me that I ought to tell my story in my own
prose, however much better your verse might be."</p>
<p>The first epoch-marking contribution to Theoretical Dynamics after
the time of Newton was undoubtedly made by Lagrange, in his discovery
of the general equations of Motion. The next great step in the same
direction was that taken by Hamilton in his discovery of a still more
comprehensive method. Of this contribution Hamilton writes to
Whewell, March 31st, 1834:—</p>
<p>"As to my late paper, a day or two ago sent off to London, it is
merely mathematical and deductive. I ventured, indeed, to call it
the 'Mecanique Analytique' of Lagrange, 'a scientific poem'; and
spoke of Dynamics, or the Science of Force, as treating of 'Power
acting by Law in Space and Time.' In other respects it is as
unpoetical and unmetaphysical as my gravest friends could desire."</p>
<p>It may well be doubted whether there is a more beautiful chapter in
the whole of mathematical philosophy than that which contains
Hamilton's dynamical theory. It is disfigured by no tedious
complexity of symbols; it condescends not to any particular problems;
it is an all embracing theory, which gives an intellectual grasp of
the most appropriate method for discovering the result of the
application of force to matter. It is the very generality of this
doctrine which has somewhat impeded the applications of which it is
susceptible. The exigencies of examinations are partly responsible
for the fact that the method has not become more familiar to students
of the higher mathematics. An eminent professor has complained that
Hamilton's essay on dynamics was of such an extremely abstract
character, that he found himself unable to extract from it problems
suitable for his examination papers.</p>
<p>The following extract is from a letter of Professor Sylvester to
Hamilton, dated 20th of September, 1841. It will show how his works
were appreciated by so consummate a mathematician as the writer:—</p>
<p>"Believe me, sir, it is not the least of my regrets in quitting this
empire to feel that I forego the casual occasion of meeting those
masters of my art, yourself chief amongst the number, whose
acquaintance, whose conversation, or even notice, have in themselves
the power to inspire, and almost to impart fresh vigour to the
understanding, and the courage and faith without which the efforts of
invention are in vain. The golden moments I enjoyed under your
hospitable roof at Dunsink, or moments such as they were, may
probably never again fall to my lot.</p>
<p>"At a vast distance, and in an humble eminence, I still promise myself
the calm satisfaction of observing your blazing course in the
elevated regions of discovery. Such national honour as you are able
to confer on your country is, perhaps, the only species of that
luxury for the rich (I mean what is termed one's glory) which is not
bought at the expense of the comforts of the million."</p>
<p>The study of metaphysics was always a favourite recreation when
Hamilton sought for a change from the pursuit of mathematics. In the
year 1834 we find him a diligent student of Kant; and, to show the
views of the author of Quaternions and of Algebra as the Science of
Pure Time on the "Critique of the Pure Reason," we quote the
following letter, dated 18th of July, 1834, from Hamilton to Viscount
Adare:—</p>
<p>"I have read a large part of the 'Critique of the Pure Reason,' and
find it wonderfully clear, and generally quite convincing.
Notwithstanding some previous preparation from Berkeley, and from my
own thoughts, I seem to have learned much from Kant's own statement
of his views of 'Space and Time.' Yet, on the whole, a large part of
my pleasure consists in recognising through Kant's works, opinions,
or rather views, which have been long familiar to myself, although
far more clearly and systematically expressed and combined by him.
. . . Kant is, I think, much more indebted than he owns, or, perhaps
knows, to Berkeley, whom he calls by a sneer, 'GUTEM Berkeley'. . .
as it were, 'good soul, well meaning man,' who was able for all that
to shake to its centre the world of human thought, and to effect a
revolution among the early consequences of which was the growth of
Kant himself."</p>
<p>At several meetings of the British Association Hamilton was a very
conspicuous figure. Especially was this the case in 1835, when the
Association met in Dublin, and when Hamilton, though then but thirty
years old, had attained such celebrity that even among a very
brilliant gathering his name was perhaps the most renowned. A
banquet was given at Trinity College in honour of the meeting. The
distinguished visitors assembled in the Library of the University.
The Earl of Mulgrave, then Lord Lieutenant of Ireland, made this the
opportunity of conferring on Hamilton the honour of knighthood,
gracefully adding, as he did so: "I but set the royal, and therefore
the national mark, on a distinction already acquired by your genius
and labours."</p>
<p>The banquet followed, writes Mr. Graves. "It was no little addition
to the honour Hamilton had already received that, when Professor
Whewell returned thanks for the toast of the University of Cambridge,
he thought it appropriate to add the words, 'There was one point
which strongly pressed upon him at that moment: it was now one
hundred and thirty years since a great man in another Trinity College
knelt down before his sovereign, and rose up Sir Isaac Newton.' The
compliment was welcomed by immense applause."</p>
<p>A more substantial recognition of the labours of Hamilton took place
subsequently. He thus describes it in a letter to Mr. Graves of 14th
of November, 1843:—</p>
<p>"The Queen has been pleased—and you will not doubt that it was
entirely unsolicited, and even unexpected, on my part—'to express
her entire approbation of the grant of a pension of two hundred
pounds per annum from the Civil List' to me for scientific services.
The letters from Sir Robert Peel and from the Lord Lieutenant of
Ireland in which this grant has been communicated or referred to have
been really more gratifying to my feelings than the addition to my
income, however useful, and almost necessary, that may have been."</p>
<p>The circumstances we have mentioned might lead to the supposition
that Hamilton was then at the zenith of his fame but this was not
so. It might more truly be said, that his achievements up to this
point were rather the preliminary exercises which fitted him for the
gigantic task of his life. The name of Hamilton is now chiefly
associated with his memorable invention of the calculus of
Quaternions. It was to the creation of this branch of mathematics
that the maturer powers of his life were devoted; in fact he gives us
himself an illustration of how completely habituated he became to the
new modes of thought which Quaternions originated. In one of his
later years he happened to take up a copy of his famous paper on
Dynamics, a paper which at the time created such a sensation among
mathematicians, and which is at this moment regarded as one of the
classics of dynamical literature. He read, he tells us, his paper
with considerable interest, and expressed his feelings of
gratification that he found himself still able to follow its
reasoning without undue effort. But it seemed to him all the time as
a work belonging to an age of analysis now entirely superseded.</p>
<p>In order to realise the magnitude of the revolution which Hamilton
has wrought in the application of symbols to mathematical
investigation, it is necessary to think of what Hamilton did beside
the mighty advance made by Descartes. To describe the character of
the quaternion calculus would be unsuited to the pages of this work,
but we may quote an interesting letter, written by Hamilton from his
death-bed, twenty-two years later, to his son Archibald, in which he
has recorded the circumstances of the discovery:—</p>
<p>"Indeed, I happen to be able to put the finger of memory upon the year
and month—October, 1843—when having recently returned from visits
to Cork and Parsonstown, connected with a meeting of the British
Association, the desire to discover the laws of multiplication
referred to, regained with me a certain strength and earnestness
which had for years been dormant, but was then on the point of being
gratified, and was occasionally talked of with you. Every morning in
the early part of the above-cited month, on my coming down to
breakfast, your (then) little brother William Edwin, and yourself,
used to ask me, 'Well papa, can you multiply triplets?' Whereto I
was always obliged to reply, with a sad shake of the head: 'No, I
can only ADD and subtract them,'</p>
<p>"But on the 16th day of the same month—which happened to be Monday,
and a Council day of the Royal Irish Academy—I was walking in to
attend and preside, and your mother was walking with me along the
Royal Canal, to which she had perhaps driven; and although she talked
with me now and then, yet an UNDERCURRENT of thought was going on in
my mind which gave at last a RESULT, whereof it is not too much to
say that I felt AT ONCE the importance. An ELECTRIC circuit seemed
to CLOSE; and a spark flashed forth the herald (as I FORESAW
IMMEDIATELY) of many long years to come of definitely directed
thought and work by MYSELF, if spared, and, at all events, on the
part of OTHERS if I should even be allowed to live long enough
distinctly to communicate the discovery. Nor could I resist the
impulse—unphilosophical as it may have been—to cut with a knife on
a stone of Brougham Bridge as we passed it, the fundamental formula
which contains the SOLUTION of the PROBLEM, but, of course, the
inscription has long since mouldered away. A more durable notice
remains, however, on the Council Books of the Academy for that day
(October 16, 1843), which records the fact that I then asked for and
obtained leave to read a Paper on 'Quaternions,' at the First General
Meeting of the Session; which reading took place accordingly, on
Monday, the 13th of November following."</p>
<p>Writing to Professor Tait, Hamilton gives further particulars of the
same event. And again in a letter to the Rev. J. W. Stubbs:—</p>
<p>"To-morrow will be the fifteenth birthday of the Quaternions. They
started into life full-grown on the 16th October, 1843, as I was
walking with Lady Hamilton to Dublin, and came up to Brougham
Bridge—which my boys have since called Quaternion Bridge. I pulled
out a pocketbook which still exists, and made entry, on which at the
very moment I felt that it might be worth my while to expend the
labour of at least ten or fifteen years to come. But then it is fair
to say that this was because I felt a problem to have been at that
moment solved, an intellectual want relieved which had haunted me for
at least fifteen years before.</p>
<p>"But did the thought of establishing such a system, in which
geometrically opposite facts—namely, two lines (or areas) which are
opposite IN SPACE give ALWAYS a positive product—ever come into
anybody's head till I was led to it in October, 1843, by trying to
extend my old theory of algebraic couples, and of algebra as the
science of pure time? As to my regarding geometrical addition of
lines as equivalent to composition of motions (and as performed by
the same rules), that is indeed essential in my theory but not
peculiar to it; on the contrary, I am only one of many who have been
led to this view of addition."</p>
<p>Pilgrims in future ages will doubtless visit the spot commemorated by
the invention of Quaternions. Perhaps as they look at that by no
means graceful structure Quaternion Bridge, they will regret that the
hand of some Old Mortality had not been occasionally employed in
cutting the memorable inscription afresh. It is now irrecoverably
lost.</p>
<p>It was ten years after the discovery that the great volume appeared
under the title of "Lectures on Quaternions," Dublin, 1853. The
reception of this work by the scientific world was such as might have
been expected from the extraordinary reputation of its author, and
the novelty and importance of the new calculus. His valued friend,
Sir John Herschel, writes to him in that style of which he was a
master:—</p>
<p>"Now, most heartily let me congratulate you on getting out your
book—on having found utterance, ore rotundo, for all that labouring
and seething mass of thought which has been from time to time sending
out sparks, and gleams, and smokes, and shaking the soil about you;
but now breaks into a good honest eruption, with a lava stream and a
shower of fertilizing ashes.</p>
<p>"Metaphor and simile apart, there is work for a twelve-month to any
man to read such a book, and for half a lifetime to digest it, and I
am glad to see it brought to a conclusion."</p>
<p>We may also record Hamilton's own opinion expressed to Humphrey
Lloyd:—</p>
<p>"In general, although in one sense I hope that I am actually growing
modest about the quaternions, from my seeing so many peeps and vistas
into future expansions of their principles, I still must assert that
this discovery appears to me to be as important for the middle of the
nineteenth century as the discovery of fluxions was for the close of
the seventeenth."</p>
<p>Bartholomew Lloyd died in 1837. He had been the Provost of Trinity
College, and the President of the Royal Irish Academy. Three
candidates were put forward by their respective friends for the
vacant Presidency. One was Humphrey Lloyd, the son of the late
Provost, and the two others were Hamilton and Archbishop Whately.
Lloyd from the first urged strongly the claims of Hamilton, and
deprecated the putting forward of his own name. Hamilton in like
manner desired to withdraw in favour of Lloyd. The wish was strongly
felt by many of the Fellows of the College that Lloyd should be
elected, in consequence of his having a more intimate association
with collegiate life than Hamilton; while his scientific eminence was
world-wide. The election ultimately gave Hamilton a considerable
majority over Lloyd, behind whom the Archbishop followed at a
considerable distance. All concluded happily, for both Lloyd and the
Archbishop expressed, and no doubt felt, the pre-eminent claims of
Hamilton, and both of them cordially accepted the office of a
Vice-President, to which, according to the constitution of the
Academy, it is the privilege of the incoming President to nominate.</p>
<p>In another chapter I have mentioned as a memorable episode in
astronomical history, that Sir J. Herschel went for a prolonged
sojourn to the Cape of Good Hope, for the purpose of submitting the
southern skies to the same scrutiny with the great telescope that his
father had given to the northern skies. The occasion of Herschel's
return after the brilliant success of his enterprise, was celebrated
by a banquet. On June 15th, 1838, Hamilton was assigned the high
honour of proposing the health of Herschel. This banquet is
otherwise memorable in Hamilton's career as being one of the two
occasions in which he was in the company of his intimate friend De
Morgan.</p>
<p>In the year 1838 a scheme was adopted by the Royal Irish Academy for
the award of medals to the authors of papers which appeared to
possess exceptionally high merit. At the institution of the medal
two papers were named in competition for the prize. One was
Hamilton's "Memoir on Algebra, as the Science of Pure Time." The
other was Macullagh's paper on the "Laws of Crystalline Reflection
and Refraction." Hamilton expresses his gratification that, mainly
in consequence of his own exertions, he succeeded in having the medal
awarded to Macullagh rather than to himself. Indeed, it would almost
appear as if Hamilton had procured a letter from Sir J. Herschel,
which indicated the importance of Macullagh's memoir in such a way as
to decide the issue. It then became Hamilton's duty to award the
medal from the chair, and to deliver an address in which he expressed
his own sense of the excellence of Macullagh's scientific work. It
is the more necessary to allude to these points, because in the whole
of his scientific career it would seem that Macullagh was the only
man with whom Hamilton had ever even an approach to a dispute about
priority. The incident referred to took place in connection with the
discovery of conical refraction, the fame of which Macullagh made a
preposterous attempt to wrest from Hamilton. This is evidently
alluded to in Hamilton's letter to the Marquis of Northampton, dated
June 28th, 1838, in which we read:—</p>
<p>"And though some former circumstances prevented me from applying to
the person thus distinguished the sacred name of FRIEND, I had the
pleasure of doing justice...to his high intellectual merits... I
believe he was not only gratified but touched, and may, perhaps,
regard me in future with feelings more like those which I long to
entertain towards him."</p>
<p>Hamilton was in the habit, from time to time, of commencing the
keeping of a journal, but it does not appear to have been
systematically conducted. Whatever difficulties the biographer may
have experienced from its imperfections and irregularities, seem to
be amply compensated for by the practice which Hamilton had of
preserving copies of his letters, and even of comparatively
insignificant memoranda. In fact, the minuteness with which
apparently trivial matters were often noted down appears almost
whimsical. He frequently made a memorandum of the name of the person
who carried a letter to the post, and of the hour in which it was
despatched. On the other hand, the letters which he received were
also carefully preserved in a mighty mass of manuscripts, with which
his study was encumbered, and with which many other parts of the
house were not unfrequently invaded. If a letter was laid aside for
a few hours, it would become lost to view amid the seething mass of
papers, though occasionally, to use his own expression, it might be
seen "eddying" to the surface in some later disturbance.</p>
<p>The great volume of "Lectures on Quaternions" had been issued, and
the author had received the honours which the completion of such a
task would rightfully bring him. The publication of an immortal work
does not, however, necessarily provide the means for paying the
printer's bill. The printing of so robust a volume was necessarily
costly; and even if all the copies could be sold, which at the time
did not seem very likely, they would hardly have met the inevitable
expenses. The provision of the necessary funds was, therefore, a
matter for consideration. The Board of Trinity College had already
contributed 200 pounds to the printing, but yet another hundred was
required. Even the discoverer of Quaternions found this a source of
much anxiety. However, the board, urged by the representation of
Humphrey Lloyd, now one of its members, and, as we have already seen,
one of Hamilton's staunchest friends, relieved him of all liability.
We may here note that, notwithstanding the pension which Hamilton
enjoyed in addition to the salary of his chair, he seems always to
have been in some what straitened circumstances, or, to use his own
words in one of his letters to De Morgan, "Though not an embarrassed
man, I am anything rather than a rich one." It appears that,
notwithstanding the world-wide fame of Hamilton's discoveries, the
only profit in a pecuniary sense that he ever obtained from any of
his works was by the sale of what he called his Icosian Game. Some
enterprising publisher, on the urgent representations of one of
Hamilton's friends in London, bought the copyright of the Icosian
Game for 25 pounds. Even this little speculation proved unfortunate
for the purchaser, as the public could not be induced to take the
necessary interest in the matter.</p>
<p>After the completion of his great book, Hamilton appeared for awhile
to permit himself a greater indulgence than usual in literary
relaxations. He had copious correspondence with his intimate friend,
Aubrey de Vere, and there were multitudes of letters from those
troops of friends whom it was Hamilton's privilege to possess. He
had been greatly affected by the death of his beloved sister Eliza, a
poetess of much taste and feeling. She left to him her many papers
to preserve or to destroy, but he said it was only after the
expiration of four years of mourning that he took courage to open her
pet box of letters.</p>
<p>The religious side of Hamilton's character is frequently illustrated
in these letters; especially is this brought out in the
correspondence with De Vere, who had seceded to the Church of Rome.
Hamilton writes, August 4, 1855:—</p>
<p>"If, then, it be painfully evident to both, that under such
circumstances there CANNOT (whatever we may both DESIRE) be NOW in
the nature of things, or of minds, the same degree of INTIMACY
between us as of old; since we could no longer TALK with the same
degree of unreserve on every subject which happened to present
itself, but MUST, from the simplest instincts of courtesy, be each on
his guard not to say what might be offensive, or, at least, painful
to the other; yet WE were ONCE so intimate, and retain still, and, as
I trust, shall always retain, so much of regard and esteem and
appreciation for each other, made tender by so many associations of
my early youth and your boyhood, which can never be forgotten by
either of us, that (as times go) TWO OR THREE VERY RESPECTABLE
FRIENDSHIPS might easily be carved out from the fragments of our
former and ever-to-be-remembered INTIMACY. It would be no
exaggeration to quote the words: 'Heu! quanto minus est cum reliquis
versari, quam tui meminisse!'"</p>
<p>In 1858 a correspondence on the subject of Quaternions commenced
between Professor Tait and Sir William Hamilton. It was particularly
gratifying to the discoverer that so competent a mathematician as
Professor Tait should have made himself acquainted with the new
calculus. It is, of course, well known that Professor Tait
subsequently brought out a most valuable elementary treatise on
Quaternions, to which those who are anxious to become acquainted with
the subject will often turn in preference to the tremendous work of
Hamilton.</p>
<p>In the year 1861 gratifying information came to hand of the progress
which the study of Quaternions was making abroad. Especially did the
subject attract the attention of that accomplished mathematician,
Moebius, who had already in his "Barycentrische Calculus" been led to
conceptions which bore more affinity to Quaternions than could be
found in the writings of any other mathematician. Such notices of
his work were always pleasing to Hamilton, and they served, perhaps,
as incentives to that still closer and more engrossing labour by
which he became more and more absorbed. During the last few years of
his life he was observed to be even more of a recluse than he had
hitherto been. His powers of long and continuous study seemed to
grow with advancing years, and his intervals of relaxation, such as
they were, became more brief and more infrequent.</p>
<p>It was not unusual for him to work for twelve hours at a stretch.
The dawn would frequently surprise him as he looked up to snuff his
candles after a night of fascinating labour at original research.
Regularity in habits was impossible to a student who had prolonged
fits of what he called his mathematical trances. Hours for rest and
hours for meals could only be snatched in the occasional the lucid
intervals between one attack of Quaternions and the next. When
hungry, he would go to see whether anything could be found on the
sideboard; when thirsty, he would visit the locker, and the one
blemish in the man's personal character is that these latter visits
were sometimes paid too often.</p>
<p>As an example of one of Hamilton's rare diversions from the all-
absorbing pursuit of Quaternions, we find that he was seized with
curiosity to calculate back to the date of the Hegira, which he found
on the 15th July, 622. He speaks of the satisfaction with which he
ascertained subsequently that Herschel had assigned precisely the
same date. Metaphysics remained also, as it had ever been, a
favourite subject of Hamilton's readings and meditations and of
correspondence with his friends. He wrote a very long letter to Dr.
Ingleby on the subject of his "Introduction to Metaphysics." In it
Hamilton alludes, as he has done also in other places, to a
peculiarity of his own vision. It was habitual to him, by some
defect in the correlation of his eyes, to see always a distinct image
with each; in fact, he speaks of the remarkable effect which the use
of a good stereoscope had on his sensations of vision. It was then,
for the first time, that he realised how the two images which he had
always seen hitherto would, under normal circumstances, be blended
into one. He cites this fact as bearing on the phenomena of
binocular vision, and he draws from it the inference that the
necessity of binocular vision for the correct appreciation of
distance is unfounded. "I am quite sure," he says, "that I SEE
DISTANCE with EACH EYE SEPARATELY."</p>
<p>The commencement of 1865, the last year of his life saw Hamilton as
diligent as ever, and corresponding with Salmon and Cayley. On April
26th he writes to a friend to say, that his health has not been good
for years past, and that so much work has injured his constitution;
and he adds, that it is not conducive to good spirits to find that he
is accumulating another heavy bill with the printer for the
publication of the "Elements." This was, indeed, up to the day of
his death, a cause for serious anxiety. It may, however, be
mentioned that the whole cost, which amounted to nearly 500 pounds,
was, like that of the previous volume, ultimately borne by the
College. Contrary to anticipation, the enterprise, even in a
pecuniary sense, cannot have been a very unprofitable one. The whole
edition has long been out of print, and as much as 5 pounds has since
been paid for a single copy.</p>
<p>It was on the 9th of May, 1865, that Hamilton was in Dublin for the
last time. A few days later he had a violent attack of gout, and on
the 4th of June he became alarmingly ill, and on the next day had an
attack of epileptic convulsions. However, he slightly rallied, so
that before the end of the month he was again at work at the
"Elements." A gratifying incident brightened some of the last days
of his life. The National Academy of Science in America had then
been just formed. A list of foreign Associates had to be chosen from
the whole world, and a discussion took place as to what name should
be placed first on the list. Hamilton was informed by private
communication that this great distinction was awarded to him by a
majority of two-thirds.</p>
<p>In August he was still at work on the table of contents of the
"Elements," and one of his very latest efforts was his letter to Mr.
Gould, in America, communicating his acknowledgements of the honour
which had been just conferred upon him by the National Academy. On
the 2nd of September Mr. Graves went to the observatory, in response
to a summons, and the great mathematician at once admitted to his
friend that he felt the end was approaching. He mentioned that he
had found in the 145th Psalm a wonderfully suitable expression of his
thoughts and feelings, and he wished to testify his faith and
thankfulness as a Christian by partaking of the Lord's Supper. He
died at half-past two on the afternoon of the 2nd of September, 1865,
aged sixty years and one month. He was buried in Mount Jerome
Cemetery on the 7th of September.</p>
<p>Many were the letters and other more public manifestations of the
feelings awakened by Hamilton's death. Sir John Herschel wrote to
the widow:—</p>
<p>"Permit me only to add that among the many scientific friends whom
time has deprived me of, there has been none whom I more deeply
lament, not only for his splendid talents, but for the excellence of
his disposition and the perfect simplicity of his manners—so great,
and yet devoid of pretensions."</p>
<p>De Morgan, his old mathematical crony, as Hamilton affectionately
styled him, also wrote to Lady Hamilton:—</p>
<p>"I have called him one of my dearest friends, and most truly; for I
know not how much longer than twenty-five years we have been in
intimate correspondence, of most friendly agreement or disagreement,
of most cordial interest in each other. And yet we did not know each
other's faces. I met him about 1830 at Babbage's breakfast table,
and there for the only time in our lives we conversed. I saw him, a
long way off, at the dinner given to Herschel (about 1838) on his
return from the Cape and there we were not near enough, nor on that
crowded day could we get near enough, to exchange a word. And this
is all I ever saw, and, so it has pleased God, all I shall see in
this world of a man whose friendly communications were among my
greatest social enjoyments, and greatest intellectual treats."</p>
<p>There is a very interesting memoir of Hamilton written by De Morgan,
in the "Gentleman's Magazine" for 1866, in which he produces an
excellent sketch of his friend, illustrated by personal reminiscences
and anecdotes. He alludes, among other things, to the picturesque
confusion of the papers in his study. There was some sort of order
in the mass, discernible however, by Hamilton alone, and any invasion
of the domestics, with a view to tidying up, would throw the
mathematician as we are informed, into "a good honest thundering
passion."</p>
<p>Hardly any two men, who were both powerful mathematicians, could have
been more dissimilar in every other respect than were Hamilton and De
Morgan. The highly poetical temperament of Hamilton was remarkably
contrasted with the practical realism of De Morgan. Hamilton sends
sonnets to his friend, who replies by giving the poet advice about
making his will. The metaphysical subtleties, with which Hamilton
often filled his sheets, did not seem to have the same attraction for
De Morgan that he found in battles about the quantification of the
Predicate. De Morgan was exquisitely witty, and though his jokes
were always appreciated by his correspondent, yet Hamilton seldom
ventured on anything of the same kind in reply; indeed his rare
attempts at humour only produced results of the most ponderous
description. But never were two scientific correspondents more
perfectly in sympathy with each other. Hamilton's work on
Quaternions, his labours in Dynamics, his literary tastes, his
metaphysics, and his poetry, were all heartily welcomed by his
friend, whose letters in reply invariably evince the kindliest
interest in all Hamilton's concerns. In a similar way De Morgan's
letters to Hamilton always met with a heartfelt response.</p>
<p>Alike for the memory of Hamilton, for the credit of his University,
and for the benefit of science, let us hope that a collected edition
of his works will ere long appear—a collection which shall show
those early achievements in splendid optical theory, those
achievements of his more mature powers which made him the Lagrange of
his country, and finally those creations of the Quaternion Calculus
by which new capabilities have been bestowed on the human intellect.</p>
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