course everywhere extended to its author, who, in spite of several
unworthy cabals, and attempts to deprive him of the credit of a
discovery peculiarly his own, was received among all ranks with the
highest distinction at home, and also gratified with various continental
honours. If he had thought fit to settle in London, he might undoubtedly
have secured wealth in proportion to his reputation; but he preferred
the quiet enjoyment of rural life and domestic happiness. His death took
place at Berkeley, from a sudden attack of apoplexy, in February, 1823,
in the seventy-fourth year of his age. The latter years of his life were
spent between Berkeley and Cheltenham, and in occasional visits to
London, in the zealous prosecution of his favourite subjects of
research, and successful endeavours to diffuse the blessings of his
discovery more widely in his own and other lands.
In England, however, these have not been so extensively felt as in some
other countries where the form of government has given facilities for
the enforcement of vaccination. The small-pox consequently prevails to a
considerable extent in this country, and especially in London. Yet the
annual number of deaths from small-pox within the bills of mortality is
at present under 700; the largest number in one year since the general
practice of vaccination having been 1299, in 1825. A century ago, when
the population certainly did not reach half its present amount, the
yearly average was 2000, the maximum being in 1796, when the mortality
swelled to 3549. That this decrease is wholly due to vaccination cannot
be doubted; the advantage, however, is partly indirect, and has arisen
from the discontinuance of the practice of inoculating for the
small-pox, which afforded security to individuals, but increased the
general mortality by keeping alive a constant source of infection. But
the most striking examples of the advantage derived from vaccination are
to be found on the continent. Thus at Berlin, where the average annual
amount of deaths from small-pox was 472 for the twenty years previous to
1802, and 1646 died in 1801, the mortality so speedily diminished after
the enforcement of vaccination by law, that in 1821 and 1822 there was
only one death in each year. These and similar instances which might be
adduced from other countries, seem almost to warrant us in adopting the
sanguine expectation of Jenner, that by means of his discovery this
disgusting and dreadful malady, from which not four in a hundred of the
human race wholly escaped, and which destroyed a tenth part of all that
were born, and disfigured where it did not destroy, may yet be swept
from the face of the earth.
The best books of reference on the subjects of this memoir are ‘Baron’s
Life of Jenner,’ ‘Moore’s History of the Cow-pox,’ Dr. Gregory’s
admirable articles in the ‘Encyclopædia of Medicine,’ and the reports of
various parliamentary committees, especially those of 1802 and 1833.
[Illustration]
MASKELYNE.
Nevil Maskelyne was born in London, October 6, 1732. He was educated at
Westminster, and in time proceeded to Catherine Hall, Cambridge, from
whence he migrated to Trinity College. He took the degree of Bachelor of
Arts, with honours, in the year 1754. In 1755, he was ordained to a
curacy near London. He had previously turned his attention to astronomy,
to which he was led by the solar eclipse of 1748; and he now formed an
acquaintance with Bradley, an astronomer of unequalled merit, whether in
discovery or practical excellence in observation, whom he assisted in
calculating his table of refractions. It is no wonder that, under such
instruction, Maskelyne should have distinguished himself afterwards as
an observer. From this period (A.D. 1750) Delambre dates the
commencement of really good observations.
In 1758 Maskelyne was elected Fellow of his college; in 1759 he became
Fellow of the Royal Society. In 1761 he went to St. Helena, to observe
the transit of Venus, and also to collect such observations as might, if
possible, enable him to detect the parallax of the fixed stars. He
failed in both objects; in the first from cloudy weather, in the second
from faulty instruments, as he supposed, though the quantity in question
is so small that its existence has not yet been detected; but he was
enabled to correct the principal errors of those instruments in a
considerable degree, and also to make very good observations on various
other points. In his voyage out and home he applied himself to perfect
the method of observing lunar distances, and deducing the longitude from
them. In 1764 he sailed to Barbadoes, to make a trial of Harrison’s
time-keeper; and in 1765 he was appointed Astronomer Royal, on the
decease of Mr. Bliss. He was then only thirty-three years of age, and
had enjoyed a rapid career of celebrity. He had published enough in the
‘British Mariner’s Guide,’ A.D. 1763, to require honourable mention of
his name and methods in every work of navigation.
[Illustration:
_Engraved by E. Scriven._
MASKELYNE.
_From the original Picture by Vanderburgh in the possession of the
Royal Society._
Under the Superintendance of the Society for the Diffusion of Useful
Knowledge.
_London, Published by Charles Knight, Ludgate Street._
]
As soon as he had obtained the post of Astronomer Royal, he began to
call the attention of the Commissioners of Longitude to the
practicability of the method of lunar distances, and proposed to them to
establish a Nautical Almanac, which should contain such an ephemeris of
the moon’s path as would make the object in view attainable. The
memorial on this subject was presented February 9, 1765, and the
evidence of various officers of the East India Company’s service was
taken as to the success of the method. The lunar tables of Mayer
furnished the proposed materials for the moon’s places; and upon the
adoption of the scheme of Maskelyne, a parliamentary reward of 3000_l._
was given to Mayer’s widow. To Maskelyne we are thus indebted for a work
which has more than any other contributed to the advancement of
navigation, in the removal of the great difficulty of finding the
longitude. It is true that this first effort could hardly then be
expected to give the longitude within a degree; but this was a great
improvement, when it is considered that the reckoning of a ship might be
out several degrees, and that chronometers had not yet been introduced.
But the ‘Nautical Almanac’ must be considered as a work addressed to
astronomers as well as seamen, from its earliest commencement. Maskelyne
saw the importance of saving the observer the trouble and risk of error
which would attend his reductions without such assistance, and
contemplated the continual improvement of the lunar tables. It is not
one of the least obligations which astronomical science owes to
Maskelyne, that since his time a very slender portion of mathematical
knowledge will enable a diligent observer to turn his means to good
account in the promotion of sidereal and even of planetary astronomy.
Without saying that the observer, as such, is employed about the highest
department of the science, or in any way recommending the lover of
observation to stop his career at that point, we may remind him that,
with the assistance of an ephemeris, such as the ‘Nautical Almanac’ of
Maskelyne did, still more as that of the present day, he can never want
the means of turning his amusements to useful purpose.
The first Nautical Almanac was published in 1767, and was continued by
Maskelyne to the end of his life. The requisite tables, intended to
accompany that work, were first published by him in 1781.
With the exception of attending the meetings of the Royal Society,
Maskelyne hardly ever quitted his observatory. His life is therefore
difficult to describe, except by its results. But in 1772 he went to
Scotland, to pursue his celebrated experiment for the discovery of the
earth’s density. The Newtonian doctrine of attraction, in the general
form, that all matter attracts all other matter, could hardly be said to
be finally established, except as a point of strong probability. That a
planet, considered as a whole, attracts a planet, might be thought to be
demonstrated, but there was no proof of matter being the agent of
attraction upon matter, _on the earth_, except in the case of magnetised
or electrified bodies. The notion that the attraction of a mountain, if
it existed, would cause a slight deviation of the plumb-line, which
should be perceptible in its effect on the observed position of the
stars, had been entertained, and the effect even suspected, but without
being reduced to absolute proof. To give an idea of the minuteness of
the angle of deviation which was to be looked for, we may state that a
pendulum ten thousand inches long, vibrating through an angle of ten
seconds, would only move through half an inch at the end farthest from
the point of suspension, and that ten seconds was, as it turned out,
nearly double of the angle in question. Maskelyne chose the mountain
Schehallien, in Perthshire, as the scene of his operations. By observing
well-known stars with an instrument depending on a plumb-line, both
north and south of the mountain, he determined the difference of
latitude of two stations, subject of course to an error if the
plumb-line were affected in its position by the attraction of the
mountain. He then measured the difference of latitude of his stations by
a trigonometrical survey, which gave their relative position by a method
independent of the plumb-line and its errors. He thus found that his
north and south plumb-lines were inclined to each other at an angle of
about eleven seconds and a half more than they should have been from
their difference of position on the earth, and that the direction of
their inclination was towards the mountain. He deduced his results from
those among his observations which he considered as the best, being
about one out of ten of the whole; but it is much to his credit as an
observer, that Baron Zach afterwards found that all his observations,
good and bad, gave the same average result as those he had selected.
Zach also established the same fact by his observations in the
neighbourhood of Marseilles, namely, that the vicinity of a mountain
affects the level, which was the instrument he used, and not the
plumb-line.
The labour of deducing an approximation to the earth’s mean density was
undertaken by Dr. Hutton. By getting the best possible estimate of the
materials of which Schehallien is composed, and comparing what we must
call the weight of the plumb-line _towards the mountain_ with its weight
towards the earth, it appeared that the mean density of the latter is
about five times that of water. This, considered as a numerical
approximation, alone and unsupported, would have been worth little,
owing to the doubt which must have existed as to the correctness of the
estimation of the mountain’s density. It would prove that there was
attraction in the mountain, but would give no very great probability to
the value of the earth’s density, as deduced. But a few years afterwards
Cavendish made an experiment, with the same object, and by an entirely
different method. By producing oscillations in leaden balls by means of
other leaden balls, and by a process of reasoning wholly free from
astronomical data, he inferred that the mean density of the earth was
five and a-half times that of water. The experiment of Cavendish was
published in 1798. It is much to be wished that the experiments of
Cavendish should be repeated on a larger scale: but the expense of the
apparatus will probably deter individuals from the attempt.
The Schehallien experiment was carried on under many difficulties and
privations; and its successful result places its author in the list of
those who first opened the road to the determination of a fundamental
element of the solar system. But brilliant as it must appear, it is by
no means the most useful of Maskelyne’s labours. Excepting Bradley, he
may almost be called the first who systematically directed his efforts
to the attainment of the minutest accuracy in astronomical
observation. His celebrated catalogue, A.D. 1790, consisted only of
thirty-six of the principal stars, but the places of these, especially
in right ascension, were determined with a degree of precision which
was then believed to be hardly attainable. The means by which he
accomplished his objects, such as taking the nearest tenth of a second
instead of the nearest second, or half second, of time in his transit
observations, the practice of uniformly observing all the wires of the
instrument, instead of one; the introduction of the movable eye-piece,
by which the several wires could all be viewed directly, instead of
obliquely, and many little things of the kind, are the indications of
a man who was familiar above his contemporaries with the sources of
error, and who had formed at once a bold estimate of the extent to
which they might be avoided, and a correct view of the means of doing
it. It is difficult to say what portion of the present improved spirit
of observation in these points may be attributed to Maskelyne, but it
certainly was not small. Delambre, who knew at least as well as any
man of his time what had been done and was doing, and who was never
profuse of praise, as his ‘History of Astronomy’ amply demonstrates,
pays him the following compliment in the memoir which he contributed
to the ‘Biographie Universelle:’—“Maskelyne était en correspondance
avec tous les astronomes de l’Europe, qu’il considérait comme ses
frères, et qui, de leur côté, le respectaient comme un doyen, dont les
travaux leur avaient été éminemment utiles.”
We have spoken, in the life of Harrison, of the controversy about the
merits of the time-piece of the latter. As Astronomer Royal, Maskelyne
was the official investigator of the rates of those instruments, and
both in the case of Harrison, and in that of Mudge, his decisions
underwent printed attacks, which he answered. Without entering into the
merits of these questions, since all the grave accusations which were
brought against him have fallen harmless, we shall only state, that
Maskelyne’s answers are full of documents, and free from passion; both
very favourable symptoms.
Dr. Maskelyne held church preferment from his college, and was besides
in possession of an easy fortune. He died Feb. 9, 1811, leaving behind
him an unblemished personal reputation, and a character for scientific
utility of the first order. He left behind him much evidence of his
utility in the labours and character of the assistants whom he formed;
all of whom, says Lalande, were useful astronomers. The late Dr.
Brinkley, Bishop of Cloyne, who added the reputation of a distinguished
mathematician to that of an eminent observer, was for sometime one of
his pupils in the practical part of the science.
[Illustration: [Schehallien.]]
[Illustration:
_Engraved by J. Posselwhite._
HOBBES.
_From a Picture by Dobson in the possession of The Royal Society._
Under the Superintendance of the Society for the Diffusion of Useful
Knowledge.
_London, Published by Charles Knight, Ludgate Street._
]
[Illustration]
HOBBES.
When Thomas Hobbes was eighty-four years of age he composed an amusing
account of his own fortunes in Latin hexameter and pentameter verses;
and in these it is mentioned that his birth was premature, owing to the
terror occasioned to his mother by a false report of the approach of the
Spanish fleet. To this accident he humorously ascribes his patriotic
zeal and the peacefulness of his disposition. We quote from a
translation made by a contemporary hand, which in elegance of expression
is on a par with the original.
“And hereupon it was, my mother dear
Did bring forth twins at once, both me, and Fear.
For this my country’s foes I e’er did hate,
With calm Peace and my Muse associate.”
It was at Malmsbury, on the 5th of April, 1588, that this very singular
man was thus called into an existence, which was continued, in perpetual
activity, for ninety-one years.
One of the earliest efforts of his talents was to translate the Medea of
Euripides into Latin iambics. At the age of fourteen, he commenced his
more serious labours at Magdalen College, Oxford; and employed five
years there in the study of logic and Aristotle’s Physics. Immediately
afterwards he entered into the family of William Cavendish, Baron
Hardwick, subsequently Earl of Devonshire, and became tutor to his
eldest son. The companion alike of his sports and his studies, Hobbes
presently acquired the affection of his pupil and the confidence of the
family; and the two young men (for they were of the same age) set out
together to travel in France and Italy.
A free intercourse with the learned men of other countries enlarged the
mind of Hobbes, and opened new channels to his investigation. And it
appears, in the first instance, that when he beheld the contempt in
which the subjects of his academical industry were generally held, he
turned from them to the more diligent study of Greek and Latin. Nor was
it his object alone to become master of the languages, but also to
meditate on the invaluable records of the history and the wisdom of the
ancients. He employed his leisure hours in the translation of
Thucydides; and he published it in the year 1628, to the end (says his
contemporary biographer), that the absurdities of the democratical
Athenians might become known to his own fellow-citizens. This was the
first of his publications; and it may have been that perhaps to which,
in later life, he attached the least importance. Yet has it so fallen
out, that after a lapse of two long centuries of slowly progressive
knowledge and wisdom, his other works are for the most part consigned to
the shelves of the profound and curious student, while the “Translation
of Thucydides” is familiar to the acquaintance and respect of every
scholar.
It is related that Hobbes, while yet a youth, was present at an assembly
of several eminent men of letters, when one of them asked, in a
contemptuous manner, _And what is sensation?_ No one attempted to make
any reply; and the question was thus silently acknowledged to be
inscrutable. This piqued his curiosity and his pride; for he was
astonished that those, who through their pretensions to wisdom so
despised others, should be ignorant of the nature of their own senses.
Accordingly he directed his deepest attention to that inquiry. The first
result of his meditation was this position: that if all things were at
_rest_, they would part with all their qualities. Hence, in his mind, it
followed, that all the principles of natural science, including the
senses of all animated things and all bodily affections, depended on the
varieties of _motion_; and to these, rather than to any inherent or
occult qualities, he referred all the phenomena of physics.
This his system of physics is amply developed in the first section (De
Corpore) of his book of the ‘Elements of Philosophy;’ which failed not
to gain him a celebrity more than proportionate to the number of his
proselytes. For many admired his ingenuity who did not adopt his
conclusions. In conjunction with these pursuits, Hobbes engaged with
zeal in the study of mathematics. He flattered himself that he had
discovered how to square the circle, and published several treatises in
relation to that celebrated problem, which at the time gained for him
considerable reputation. In 1647 he was appointed mathematical tutor to
the Prince of Wales. He engaged in a long mathematical controversy with
Dr. Wallis, of which an amusing account will be found in D’Israeli’s
‘Quarrels of Authors,’ vol. 3. Wallis, however, was an adversary
entirely above Hobbes’ strength in this department of science.
If Hobbes had confined his exertions to the pursuits of classical
literature and physical philosophy, he would have spent a more peaceful,
and therefore to him a happier, existence. But in the tumultuous times
in which he lived, with a mind habituated to deep investigations, it was
scarcely possible that he should do otherwise than fix his attention on
the political phenomena which were passing before him, and endeavour to
trace their causes and solve their difficulties. After a residence of
three years in England, he returned to Paris in 1640, and enjoyed the
society of some of the distinguished men who were collected around
Cardinal Richelieu. There he wrote his first political work, the book
_De Cive_, which he published in 1646. He then proceeded to compose a
much more elaborate treatise on the same subject, which he published in
England in the year 1651; this was his _Leviathan_—a name associated
with that of Hobbes in the mind of every reader, though the _peculiar_
principles which are embodied under it are now known to few. Suffice it
here to say, that the object of this work was to give a decided support
to the monarchical institution: to show that there could be no safety
without peace, no peace without a strong government; that arms and money
were the elements which alone could give that strength; that even arms
will scarcely avail to this end, unless placed in a single hand, or if
opposed (as is the case in religious dissension), by motives and
principles which do not terminate in this world.
Political researches in that age necessarily involved theological, or at
least ecclesiastical, principles; and Hobbes had not feared to denounce
some of the antient usurpations of the clergy, and to pronounce
religious concord to be absolutely essential to the civil happiness of a
people: and while he broached some principles not well pleasing to the
pretensions of the hierarchy of the day, he advanced others which were
thought to end, by no violent interpretation, in absolute infidelity.
Accordingly, the theologians assailed him from every quarter; and his
work, while it divided learned laymen, some of whom thought it a marvel
of political genius, others a dangerous and unseemly monster, was
condemned by the unanimous indignation of the ecclesiastical body. The
churchmen of Rome united in hostility with those of England against
doctrines which were dangerous to the common prerogatives of the whole
order, if not to the integrity of religion itself. The latter, being
more closely attacked, were more violent in their enmity. They denounced
the opinions as false and heretical; and the divines of Cambridge went
so far as publicly to stigmatize the author as an atheist. Besides this,
he did not even escape the charges of being ill disposed to royalty, and
a disguised adversary to the party of the king. These calumnies (such at
least he constantly asserted both to be,) deprived him of the patronage
of the Court, and seemed at one time even to have endangered his
personal safety; insomuch that, under the Commonwealth, he found it
expedient to escape from his enemies at Paris, and take refuge among
those, whose enmity he had rather deserved, the republicans of England.
He escaped however the fate, so common to men of moderation in violent
times, of being persecuted by both parties; and only sustained the
animosity of that which he had intended to serve.
Hobbes was a decided Episcopalian. He studied in all matters to conform
both to the doctrines and the ceremonies of the church established; and
avoided, even with a feeling of dislike, the conventicles of the
Puritans. Still less did he incline, on the other hand, to the Roman
Catholic faith. During a dangerous illness, which he suffered with great
firmness at Paris, when he was supposed to be on the point of death, an
intimate friend, named Mersenne, a learned Franciscan, approached him
with spiritual consolation, and pressed him to depart in communion with
the Roman church. Hobbes calmly replied, “Father, I have long ago
considered all those matters well, and it would trouble me to reconsider
them now. You can entertain me on some more agreeable subject. When did
you see Gassendi?”