certain extent, in the business carried on by his father. It is true
that he does not give any explicit details, yet there are frequent
references to journeys which he had to take on business matters. But
the time now approached when Flamsteed was to start on an independent
career, and it appears that he took his degree in Cambridge with the
object of entering into holy orders, so that he might settle in a
small living near Derby, which was in the gift of a friend of his
father, and would be at the disposal of the young astronomer. This
scheme was, however, not carried out, but Flamsteed does not tell us
why it failed, his only remark being, that "the good providence of
God that had designed me for another station ordered it otherwise."
Sir Jonas Moore, one of the influential friends whom Flamsteed's
talents had attracted, seems to have procured for him the position of
king's astronomer, with a salary of 100 pounds per annum. A larger
salary appears to have been designed at first for this office, which
was now being newly created, but as Flamsteed was resolved on taking
holy orders, a lesser salary was in his case deemed sufficient. The
building of the observatory, in which the first Astronomer Royal was
to be installed, seems to have been brought about, or, at all events,
its progress was accelerated, in a somewhat curious manner.
A Frenchman, named Le Sieur de S. Pierre, came over to London to
promulgate a scheme for discovering longitudes, then a question of
much importance. He brought with him introductions to distinguished
people, and his mission attracted a great deal of attention. The
proposals which he made came under Flamsteed's notice, who pointed
out that the Frenchman's projects were quite inapplicable in the
present state of astronomical science, inasmuch as the places of the
stars were not known with the degree of accuracy which would be
necessary if such methods were to be rendered available. Flamsteed
then goes on to say:--"I heard no more of the Frenchman after this;
but was told that my letters had been shown King Charles. He was
startled at the assertion of the fixed stars' places being false in
the catalogue, and said, with some vehemence, he must have them anew
observed, examined, and corrected, for the use of his seamen."
The first question to be settled was the site for the new
observatory. Hyde Park and Chelsea College were both mentioned as
suitable localities, but, at Sir Christopher Wren's suggestion,
Greenwich Hill was finally resolved upon. The king made a grant of
five hundred pounds of money. He gave bricks from Tilbury Fort,
while materials, in the shape of wood, iron, and lead, were available
from a gatehouse demolished in the Tower. The king also promised
whatever further material aid might be shown to be necessary. The
first stone of the Royal Observatory was laid on August 10th, 1675,
and within a few years a building was erected in which the art of
modern practical astronomy was to be created. Flamsteed strove with
extraordinary diligence, and in spite of many difficulties, to obtain
a due provision of astronomical instruments, and to arrange for the
carrying on of his observations. Notwithstanding the king's
promises, the astronomer was, however, but scantily provided with
means, and he had no assistants to help him in his work. It follows
that all the observations, as well as the reductions, and, indeed,
all the incidental work of the observatory, had to be carried on by
himself alone. Flamsteed, as we have seen, had, however, many
staunch friends. Sir Jonas Moore in particular at all times rendered
him most valuable assistance, and encouraged him by the warm sympathy
and keen interest which he showed in astronomy. The work of the
first Astronomer Royal was frequently interrupted by recurrent
attacks of the complaints to which we have already referred. He says
himself that "his distempers stick so close that that he cannot
remove them," and he lost much time by prostration from headaches, as
well as from more serious affections.
The year 1678 found him in the full tide of work in his observatory.
He was specially engaged on the problem of the earth's motion, which
he sought to derive from observations of the sun and of Venus. But
this, as well as many other astronomical researches which he
undertook, were only subsidiary to that which he made the main task
of his life, namely, the formation of a catalogue of fixed stars. At
the time when Flamsteed commenced his career, the only available
catalogue of fixed stars was that of Tycho Brahe. This work had been
published at the commencement of the seventeenth century, and it
contained about a thousand stars. The positions assigned to these
stars, though obtained with wonderful skill, considering the many
difficulties under which Tycho laboured, were quite inaccurate when
judged by our modern standards. Tycho's instruments were necessarily
most rudely divided, and he had, of course, no telescopes to aid him.
Consequently it was merely by a process of sighting that he could
obtain the places of the stars. It must further be remembered that
Tycho had no clocks, and no micrometers. He had, indeed, but little
correct knowledge of the motions of the heavenly bodies to guide
him. To determine the longitudes of a few principal stars he
conceived the ingenious idea of measuring by day the position of
Venus with respect to the sun, an observation which the exceptional
brightness of this planet rendered possible without telescopic aid,
and then by night he observed the position of Venus with regard to
the stars.
It has been well remarked by Mr. Baily, in his introduction to the
"British Catalogue of Stars," that "Flamsteed's observations, by a
fortunate combination of circumstances, commenced a new and a
brilliant era. It happened that, at that period, the powerful mind
of Newton was directed to this subject; a friendly intercourse then
existed between these two distinguished characters; and thus the
first observations that could lay any claim to accuracy were at once
brought in aid of those deep researches in which our illustrious
geometer was then engaged. The first edition of the 'Principia'
bears testimony to the assistance afforded by Flamsteed to Newton in
these inquiries; although the former considers that the
acknowledgment is not so ample as it ought to have been."
Although Flamsteed's observations can hardly be said to possess the
accuracy of those made in more recent times, when instruments so much
superior to his have been available, yet they possess an interest of
a special kind from their very antiquity. This circumstance renders
them of particular importance to the astronomer, inasmuch as they are
calculated to throw light on the proper motions of the stars.
Flamsteed's work may, indeed, be regarded as the origin of all
subsequent catalogues, and the nomenclature which he adopted, though
in some respects it can hardly be said to be very defensible, is,
nevertheless, that which has been adopted by all subsequent
astronomers. There were also a great many errors, as might be
expected in a work of such extent, composed almost entirely of
numerical detail. Many of these errors have been corrected by Baily
himself, the assiduous editor of "Flamsteed's Life and Works," for
Flamsteed was so harassed from various causes in the latter part of
his life, and was so subject to infirmities all through his career,
that he was unable to revise his computations with the care that
would have been necessary. Indeed, he observed many additional stars
which he never included in the British Catalogue. It is, as Baily
well remarks, "rather a matter of astonishment that he accomplished
so much, considering his slender means, his weak frame, and the
vexations which he constantly experienced."
Flamsteed had the misfortune, in the latter part of his life, to
become estranged from his most eminent scientific contemporaries. He
had supplied Newton with places of the moon, at the urgent
solicitation of the author of the "Principia," in order that the
lunar theory should be carefully compared with observation. But
Flamsteed appears to have thought that in Newton's further request
for similar information, he appeared to be demanding as a right that
which Flamsteed considered he was only called upon to render as a
favour. A considerable dispute grew out of this matter, and there
are many letters and documents, bearing on the difficulties which
subsequently arose, that are not, perhaps, very creditable to either
party.
Notwithstanding his feeble constitution, Flamsteed lived to the age
of seventy-three, his death occurring on the last day of the year
1719.
HALLEY.
Isaac Newton was just fourteen years of age when the birth of Edmund
Halley, who was destined in after years to become Newton's warmly
attached friend, and one of his most illustrious scientific
contemporaries, took place. There can be little doubt that the fame
as an astronomer which Halley ultimately acquired, great as it
certainly was, would have been even greater still had it not been
somewhat impaired by the misfortune that he had to shine in the same
sky as that which was illumined by the unparalleled genius of Newton.
Edmund Halley was born at Haggerston, in the Parish of St. Leonard's,
Shoreditch, on October 29th, 1656. His father, who bore the same
name as his famous son, was a soap-boiler in Winchester Street,
London, and he had conducted his business with such success that he
accumulated an ample fortune. I have been unable to obtain more than
a very few particulars with respect to the early life of the future
astronomer. It would, however, appear that from boyhood he showed
considerable aptitude for the acquisition of various kinds of
learning, and he also had some capacity for mechanical invention.
Halley seems to have received a sound education at St. Paul's School,
then under the care of Dr. Thomas Gale.
Here, the young philosopher rapidly distanced his competitors in the
various branches of ordinary school instruction. His superiority
was, however, most conspicuous in mathematical studies, and, as a
natural development of such tastes, we learn that by the time he had
left school he had already made good progress in astronomy. At the
age of seventeen he was entered as a commoner at Queen's College,
Oxford, and the reputation that he brought with him to the University
may be inferred from the remark of the writer of "Athenae
Oxonienses," that Halley came to Oxford "with skill in Latin, Greek,
and Hebrew, and such a knowledge of geometry as to make a complete
dial." Though his studies were thus of a somewhat multifarious
nature, yet it is plain that from the first his most favourite
pursuit was astronomy. His earliest efforts in practical observation
were connected with an eclipse which he observed from his father's
house in Winchester Street. It also appears that he had studied
theoretical branches of astronomy so far as to be conversant with the
application of mathematics to somewhat abstruse problems.
Up to the time of Kepler, philosophers had assumed almost as an axiom
that the heavenly bodies must revolve in circles and that the motion
of the planet around the orbit which it described must be uniform. We
have already seen how that great philosopher, after very persevering
labour, succeeded in proving that the orbits of the planets were not
circles, but that they were ellipses of small eccentricity. Kepler
was, however, unable to shake himself free from the prevailing notion
that the angular motion of the planet ought to be of a uniform
character around some point. He had indeed proved that the motion
round the focus of the ellipse in which the sun lies is not of this
description. One of his most important discoveries even related to
the fact that at some parts of its orbit a planet swings around the
sun with greater angular velocity than at others. But it so happens
that in elliptic tracks which differ but little from circles, as is
the case with all the more important planetary orbits, the motion
round the empty focus of the ellipse is very nearly uniform. It
seemed natural to assume, that this was exactly the case, in which
event each of the two foci of the ellipse would have had a special
significance in relation to the movement of the planet. The youthful
Halley, however, demonstrated that so far as the empty focus was
concerned, the movement of the planet around it, though so nearly
uniform, was still not exactly so, and at the age of nineteen, he
published a treatise on the subject which at once placed him in the
foremost rank amongst theoretical astronomers.
But Halley had no intention of being merely an astronomer with his
pen. He longed to engage in the practical work of observing. He saw
that the progress of exact astronomy must depend largely on the
determination of the positions of the stars with all attainable
accuracy. He accordingly determined to take up this branch of work,
which had been so successfully initiated by Tycho Brahe.
At the present day, astronomers of the great national observatories
are assiduously engaged in the determination of the places of the
stars. A knowledge of the exact positions of these bodies is indeed
of the most fundamental importance, not alone for the purposes of
scientific astronomy, but also for navigation and for extensive
operations of surveying in which accuracy is desired. The fact that
Halley determined to concentrate himself on this work shows clearly
the scientific acumen of the young astronomer.
Halley, however, found that Hevelius, at Dantzig, and Flamsteed, the
Astronomer Royal at Greenwich, were both engaged on work of this
character. He accordingly determined to direct his energies in a way
that he thought would be more useful to science. He resigned to the
two astronomers whom I have named the investigation of the stars in
the northern hemisphere, and he sought for himself a field hitherto
almost entirely unworked. He determined to go to the southern
hemisphere, there to measure and survey those stars which were
invisible in Europe, so that his work should supplement the labours
of the northern astronomers, and that the joint result of his labours
and of theirs might be a complete survey of the most important stars
on the surface of the heavens.
In these days, after so many ardent students everywhere have devoted
themselves to the study of Nature, it seems difficult for a beginner
to find a virgin territory in which to commence his explorations.
Halley may, however, be said to have enjoyed the privilege of
commencing to work in a magnificent region, the contents of which
were previously almost entirely unknown. Indeed none of the stars
which were so situated as to have been invisible from Tycho Brahe's
observatory at Uraniborg, in Denmark, could be said to have been
properly observed. There was, no doubt, a rumour that a Dutchman had
observed southern stars from the island of Sumatra, and certain stars
were indicated in the southern heavens on a celestial globe. On
examination, however, Halley found that no reliance could be placed
on the results which had been obtained, so that practically the field
before him may be said to have been unworked.
At the age of twenty, without having even waited to take that degree
at the university which the authorities would have been glad to
confer on so promising an undergraduate, this ardent student of
Nature sought his father's permission to go to the southern
hemisphere for the purpose of studying the stars which lie around the
southern pole. His father possessed the necessary means, and he had
likewise the sagacity to encourage the young astronomer. He was
indeed most anxious to make everything as easy as possible for so
hopeful a son. He provided him with an allowance of 300 pounds a
year, which was regarded as a very munificent provision in those
days. Halley was also furnished with letters of recommendation from
King Charles II., as well as from the directors of the East India
Company. He accordingly set sail with his instruments in the year
1676, in one of the East India Company's ships, for the island of St.
Helena, which he had selected as the scene of his labours.
[PLATE: HALLEY.]
After an uneventful voyage of three months, the astronomer landed on
St. Helena, with his sextant of five and a half feet radius, and a
telescope 24 feet long, and forthwith plunged with ardour into his
investigation of the southern skies. He met, however, with one very
considerable disappointment. The climate of this island had been
represented to him as most favourable for astronomical observation;
but instead of the pure blue skies he had been led to expect, he
found that they were almost always more or less clouded, and that
rain was frequent, so that his observations were very much
interrupted. On this account he only remained at St. Helena for a
single year, having, during that time, and in spite of many
difficulties, accomplished a piece of work which earned for him the
title of "our southern Tycho." Thus did Halley establish his fame as
an astronomer on the same lonely rock in mid-Atlantic, which nearly a
century and a-half later became the scene of Napoleon's imprisonment,
when his star, in which he believed so firmly, had irretrievably set.
On his return to England, Halley prepared a map which showed the
result of his labours, and he presented it to the king, in 1677.
Like his great predecessor Tycho, Halley did not altogether disdain
the arts of the courtier, for he endeavoured to squeeze a new
constellation into the group around the southern pole which he styled
"The Royal Oak," adding a description to the effect that the
incidents of which "The Royal Oak" was a symbol were of sufficient
importance to be inscribed on the surface of the heavens.
There is reason to think that Charles II. duly appreciated the
scientific renown which one of his subjects had achieved, and it was
probably through the influence of the king that Halley was made a
Master of Arts at Oxford on November 18th, 1678. Special reference
was made on the occasion to his observations at St. Helena, as
evidence of unusual attainments in mathematics and astronomy. This
degree was no small honour to such a young man, who, as we have seen,
quitted his university before he had the opportunity of graduating in
the ordinary manner.
On November 30th, in the same year, the astronomer received a further
distinction in being elected a Fellow of the Royal Society. From
this time forward he took a most active part in the affairs of the
Society, and the numerous papers which he read before it form a very
valuable part of that notable series of volumes known as the
"Philosophical Transactions." He was subsequently elected to the
important office of secretary to the Royal Society, and he discharged
the duties of his post until his appointment to Greenwich
necessitated his resignation.
Within a year of Halley's election as a Fellow of the Royal Society,
he was chosen by the Society to represent them in a discussion which
had arisen with Hevelius. The nature of this discussion, or rather
the fact that any discussion should have been necessary, may seem
strange to modern astronomers, for the point is one on which it would
now seem impossible for there to be any difference of opinion. We
must, however, remember that the days of Halley were, comparatively
speaking, the days of infancy as regards the art of astronomical
observation, and issues that now seem obvious were often, in those
early times, the occasions of grave and anxious consideration. The
particular question on which Halley had to represent the Royal
Society may be simply stated. When Tycho Brahe made his memorable
investigations into the places of the stars, he had no telescopes to
help him. The famous instruments at Uraniborg were merely provided
with sights, by which the telescope was pointed to a star on the same
principle as a rifle is sighted for a target. Shortly after Tycho's
time, Galileo invented the telescope. Of course every one admitted
at once the extraordinary advantages which the telescope had to
offer, so far as the mere question of the visibility of objects was
concerned. But the bearing of Galileo's invention upon what we may
describe as the measuring part of astronomy was not so immediately
obvious. If a star be visible to the unaided eye, we can determine
its place by such instruments as those which Tycho used, in which no
telescope is employed. We can, however, also avail ourselves of an
instrument in which we view the star not directly but through the
intervention of the telescope. Can the place of the star be
determined more accurately by the latter method than it can when the
telescope is dispensed with? With our present knowledge, of course,
there is no doubt about the answer; every one conversant with
instruments knows that we can determine the place of a star far more
accurately with the telescope than is possible by any mere sighting
apparatus. In fact an observer would be as likely to make an error
of a minute with the sighting apparatus in Tycho's instrument, as he
would be to make an error of a second with the modern telescope, or,
to express the matter somewhat differently, we may say, speaking
quite generally, that the telescopic method of determining the places
of the stars does not lead to errors more than one-sixtieth part as
great as which are unavoidable when we make use of Tycho's method.
But though this is so apparent to the modern astronomer, it was not
at all apparent in the days of Halley, and accordingly he was sent
off to discuss the question with the Continental astronomers.
Hevelius, as the representative of the older method, which Tycho had
employed with such success, maintained that an instrument could be
pointed more accurately at a star by the use of sights than by the
use of a telescope, and vigorously disputed the claims put forward by
those who believed that the latter method was the more suitable. On
May 14th, 1679, Halley started for Dantzig, and the energetic
character of the man may be judged from the fact that on the very
night of his arrival he commenced to make the necessary
observations. In those days astronomical telescopes had only
obtained a fractional part of the perfection possessed by the
instruments in our modern observatories, and therefore it may not be
surprising that the results of the trial were not immediately
conclusive. Halley appears to have devoted much time to the
investigation; indeed, he remained at Dantzig for more than a
twelve-month. On his return to England, he spoke highly of the skill
which Hevelius exhibited in the use of his antiquated methods, but
Halley was nevertheless too sagacious an observer to be shaken in his
preference for the telescopic method of observation.
The next year we find our young astronomer starting for a Continental
tour, and we, who complain if the Channel passage lasts more than an
hour or two, may note Halley's remark in writing to Hooke on June
15th, 1680: "Having fallen in with bad weather we took forty hours in
the journey from Dover to Calais." The scientific distinction which
he had already attained was such that he was received in Paris with
marked attention. A great deal of his time seems to have been passed
in the Paris observatory, where Cassini, the presiding genius,
himself an astronomer of well-deserved repute, had extended a hearty
welcome to his English visitor. They made observations together of
the place of the splendid comet which was then attracting universal
attention, and Halley found the work thus done of much use when he
subsequently came to investigate the path pursued by this body.
Halley was wise enough to spare no pains to derive all possible
advantages from his intercourse with the distinguished savants of the
French capital. In the further progress of his tour he visited the
principal cities of the Continent, leaving behind him everywhere the
memory of an amiable disposition and of a rare intelligence.
After Halley's return to England, in 1682, he married a young lady
named Mary Tooke, with whom he lived happily, till her death
fifty-five years later. On his marriage, he took up his abode in
Islington, where he erected his instruments and recommenced his
observations.