staff, and later in life retired on half-pay, from which period he
devoted himself entirely to science. When Parliament, in the years
1818-19, determined on establishing an uniform system of weights
and measures, Captain Kater, in conjunction with Sir Joseph Banks,
Sir George Clerk, Davies Gilbert, and Drs. Wollaston and Young, was
appointed to investigate this most important subject; and he instituted
a series of experiments with a pendulum made of a bar of brass, 1½
inches wide and 1/8 of an inch thick, to which two knife-edges of a
kind of steel prepared in India, and known by the name of wootz, were
attached, playing upon agate plates. The knife-edges were placed in a
parallel direction on the brass bar, facing opposite ways upon either
of which it might be swung. They were so arranged, that when either
was used as the point of suspension the other nearly represented the
centre of oscillation, and by means of a small adjustable weight,
this condition might be accurately fulfilled. These experiments were
made in the house of Mr. H. Browne, F.R.S., which was situated in
a part of Portland Place not likely to be disturbed by carriages.
They occupied Captain Kater's close attention for several years;
and he has permanently attached his name to the beautiful theorem
of Huygens respecting the reciprocity of the centres of oscillation
and suspension, and their consequent quality of convertibility.
Although this was a property already known to belong to the centre
of oscillation, it had never hitherto been practically applied to
determine the exact length of a pendulum vibrating seconds; it was,
therefore, highly creditable to his ingenuity, and claims the same
order of merit as an original invention. In this, as well as in Kater's
laborious inquiries respecting a standard of weights and measures,
even where his conclusions have not escaped all the chances of error,
he has led the way to the still more delicate researches which have
followed.
Captain Kater also instituted a series of experiments as to the best
kind of steel and shape for compass needles; it resulted in the
adoption of the shear clock-spring steel, and the pierced rhombus form,
in the proportion of five inches in length to two in width. In the year
1831 he received the gold medal of the Royal Astronomical Society,
for the construction of his floating collimator, an instrument for
ascertaining the accurate zero or level points of divided astronomical
instruments. The optical principle upon which it depends is a very
beautiful one, and the invention of Kater, with several improvements in
point of form, has become the auxiliary of nearly every observatory in
the world, being one of those small but happy improvements which affect
materially the progress of science. Most of the learned societies in
Great Britain and on the Continent testified at different times their
sense of the value of his services, by enrolling him among their
members. The Emperor of Russia employed him to construct standards for
the weights and measures of his dominions, and was so pleased with the
execution of them, that he presented Kater with the Order of St. Anne
and a diamond snuff-box. The greater part of his publications appeared
in the 'Philosophical Transactions' of the Royal Society, chiefly
between the years 1813 and 1828.
Captain Kater died from a severe affection of the lungs, at his
residence, York Gate, in the fifty-third year of his age.--_Athenæum_,
May, 1835.--_Weld's History of the Royal Society._ London,
1848.--_Monthly Notices of the Royal Astronomical Society_, vol. 3,
February, 1836.--_Sixth Dissertation Encyclopædia Britannica_, Eighth
Edition.
SIR JOHN LESLIE, F.R.S.E., &c.
Born April 16, 1766. Died November 3, 1832.
Sir John Leslie, Professor of Natural Philosophy in the University of
Edinburgh, the son of a poor joiner or cabinetmaker, was born at the
village of Largo, in the county of Fife. Although both weak and sickly
as a child, he soon acquired considerable knowledge of mathematical and
physical science, and at the age of eleven attracted the notice of Mr.
Oliphant, the minister of the parish, by his precocious attainments.
This gentleman kindly lent young Leslie some scientific books, and
strongly advised him to continue the study of Latin, for which he had
a great aversion, although in after life he attained considerable
proficiency in that language.
He also became known to Professors Robison and Stewart, of Edinburgh,
and by their advice was sent, in his thirteenth year, to the University
of St. Andrew's, to study mathematics under Professor Vilant. Here, at
the end of the first session, his abilities procured him the second
prize, and likewise attracted the notice of the Earl of Kinnoull, then
Chancellor of the University, who undertook to defray the expenses
of his education, provided that he would enter the Church. Leslie
prosecuted his studies at this university during six sessions, and
became about this time acquainted with Playfair and Dr. Small.
In 1783-4 he quitted St. Andrews and went to Edinburgh, where, though
he formally entered the Divinity Hall, he contrived to devote his first
session to the sciences, particularly chemistry; in fact, Leslie seems
early to have relinquished all thoughts of the Church--a resolution
hastened by the death of his patron, the Earl of Kinnoull, shortly
after his removal to Edinburgh. While engaged at the university, he
also acted as tutor to Mr. Douglas, afterwards Lord Reston, the nephew
of Dr. Adam Smith, and he thus became known to that philosopher, who
treated him kindly, and occasionally favoured him with directions as to
his pursuits. Leslie's first essay, 'On the Resolution of Indeterminate
Problems,' was composed about this time, and read to the Royal
Society of Edinburgh by Mr. Playfair, in 1788, and published in their
'Transactions' for 1790.
In 1788, he became tutor to two young Americans of the name of
Randolph, and accompanied them to Virginia, where he remained for about
a twelvemonth, during which time he visited New York, Philadelphia,
&c. In January 1790, carrying, among other letters of recommendation,
one from Adam Smith, Leslie repaired to London, with the intention of
delivering a course of lectures on natural philosophy; but finding,
to use his own words, that "rational lectures would not succeed," he
employed himself for some time in writing for the 'Monthly Review,' and
in other literary occupations.
In April 1790, he became tutor to the younger Wedgewoods, of Etruria,
in Staffordshire, who had been his former fellow-students, and with
whom he remained until the close of 1792. Leslie was likewise employed
during this period in experimental investigations, and in completing
a translation of Buffon's 'Natural History of Birds,' published in
1793, in nine volumes, for which he received a considerable sum,--the
foundation of that pecuniary competency which his industrious and
prudent habits enabled him ultimately to acquire.
During the years 1794-5 he resided at Largo, occupied upon a long
series of hygrometrical experiments, during the course of which he
invented his differential thermometer, the parent, as it may be called,
of his subsequent inventions--the hygroscope, photometer, pyroscope,
æthrioscope, and atmometer. Although Leslie has been accused of having
plagiarized this invention either from Van Helmont, who died in 1644,
or from John Christopher Sturmius, who died sixty years later, he
at all events showed, by his skilful and fruitful employment of the
disputed invention, how much he surpassed, and how little he needed the
help of, him whom he is ungenerously supposed to have robbed of his
legitimate honours.
In 1800 he wrote several papers, on different branches of physics, in
Nicholson's 'Philosophical Journal,' which resulted in the publication
at London, in 1804, of his 'Experimental Inquiry into the Nature and
Propagation of Heat.' The originality and boldness of the peculiar
doctrines contained in this work, and the number of new and important
facts disclosed by its ingenious experimental combinations, rendered
it an object of extraordinary interest in the scientific world. The
Royal Society of London unanimously adjudged to its author the Rumford
medal; and although paradoxical in many of its theories, defective
in arrangement, and over ambitious in style, this work is almost
unrivalled in the entire range of physical science, for its indication
of vigorous and inventive genius.
Previous to this period of life, Leslie had appeared twice as a
candidate for an academical chair; first in the University of St.
Andrew's, afterwards in that of Glasgow; but on both occasions without
success. He now became a candidate for the Mathematical chair at
Edinburgh, vacant through the promotion of Professor Playfair to the
chair of Natural Philosophy. After a severe contest, during which much
party spirit was displayed, owing to his principal competitor, Dr.
Thomas Macknight, one of the ministers of Edinburgh, being supported by
the majority of the city clergy, Leslie was, in March, 1805, elected
to the Mathematical chair. He entered immediately upon his official
duties, which he continued to discharge with zeal and assiduity during
the following fourteen years.
Notwithstanding the labours which these duties entailed upon him,
Leslie continued his experimental inquiries, and in June, 1810,
discovered his beautiful process of artificial congelation, by which
he was enabled to produce ice, and even to freeze mercury at pleasure.
The process consists of a combination of the powers of rarefaction
and absorption, effected by placing a very strong absorbent under the
receiver of an air-pump. This experiment was performed in London in
1811, before a meeting of some members of the Royal Society; and the
discovery was announced in the same year in the 'Memoirs' of the French
Institute. He explained his experiments and views on this subject in
1813, in a volume published at Edinburgh, entitled, 'A short Account of
Experiments and Instruments depending on the Relations of Air to Heat
and Moisture.' Closely connected with the subject of this treatise was
an ingenious paper, published in 1818, in the 'Transactions' of the
Royal Society of Edinburgh, under the title, 'On certain Impressions
of Cold transmitted from the Higher Atmosphere; with a Description of
an Instrument to Measure them.' The æthrioscope was the instrument here
alluded to.
In 1819, upon the death of Playfair, Leslie was called to the chair of
Natural Philosophy, when his first care was directed to the extension
of the apparatus required in the more enlarged series of experiments
which he thought necessary for the illustration of the course. "This,
indeed," says his biographer, Mr. Napier, "was an object of which
he never lost sight; and it is due to him to state, that, through
his exertions, the means of experimental illustration in the Natural
Philosophy class were for the first time made worthy of the place."
In 1823 he published, chiefly for the use of this class, his 'Elements
of Natural Philosophy,' a second edition of which was published in
1829, with corrections and additions. Besides the above-mentioned
works, Leslie wrote the following:--'Elements of Geometry, Geometrical
Analysis and Plane Trigonometry,' in 1809; 'Observations on Electrical
Theories,' published in 1824, in the 'Edinburgh Philosophical Journal;'
also many articles in the 'Edinburgh Review;' and the articles on
Achromatic Glasses; Acoustics; Aeronautics; Andes; Angle and Trisection
of Angle; Arithmetic; Atmometer; Barometer; Barometrical Measurements;
Climate; Cold and Congelation; Dew; Interpolation; and Meteorology, in
the seventh edition of the 'Encyclopædia Britannica.'
Early in the year 1832, on the recommendation of Lord Brougham, then
Lord High Chancellor, Leslie was created, along with several other
eminent men of science, a Knight of the Guelphic Order. He was also a
member of the Royal Society of Edinburgh, and in 1820 had been elected
a corresponding member of the French Institute. During the month of
October, whilst engaged in superintending some improvements on his
grounds, he caught a severe cold, which was followed by erysipelas
in one of his legs, and his neglect of this, owing to a contempt for
medicine, and great confidence in his own strength and durability,
resulted in his death, at Coates, in the November following, at the age
of sixty-six.
Sir John Leslie has been described as rivalling all his contemporaries
in that creative faculty which discovers, often by an intuitive
glimpse, the hidden secrets of nature; but possessing in a less
degree the powers of judgment and reason, being thus often led in
his speculations to results glaringly inconsistent. His exquisite
instruments, and his experimental combinations, will, however, ever
test the utility, no less than the originality of his labours, and
will continue to act as aids to farther discovery.--_Encyclopædia
Britannica_, Eighth Edition.--_Abstract of Memoir of Sir John Leslie,
by Macvey Napier, English Cyclopædia._ London, 1856.
NEVIL MASKELYNE, D.D., F.R.S.
MEMBER OF THE INSTITUTE OF FRANCE, ETC.
Born October 6, 1732. Died February 9, 1811.
This most accurate and industrious astronomer was born in London, and
was the son of Mr. Edmund Maskelyne, a gentleman of respectable family
in Wiltshire. At the age of nine Maskelyne was sent to Westminster
school, where he early began to distinguish himself, and to display a
decided taste for the study of optics and astronomy.
The great solar eclipse, which occurred in 1748 was, however, the
immediate cause of his directing his attention to these sciences,
and from that period he devoted himself with ardour to the study of
mathematics as subservient to that of astronomy. It is a curious fact
that the same eclipse is said to have produced a similar effect upon
the French astronomer Lalande, who was only three months older than his
English contemporary.
Soon after this Maskelyne entered the University of Cambridge as a
member of Catherine Hall, removing afterwards to Trinity, where he took
the degree of Bachelor of Arts with great credit in 1754, and proceeded
regularly through the succeeding stages of academical rank in divinity.
In 1755 he was ordained to a curacy at Barnet, and in the following
year obtained a fellowship at Trinity. In the year 1758 he was elected
a fellow of the Royal Society, previous to which event he had become
acquainted with Dr. Bradley, and had determined to make astronomy the
principal pursuit of his life, feeling that it was perfectly compatible
with an enlightened devotion to the duties of his own profession.
1761 marks the period when Maskelyne commenced his public career as
an astronomer. During that year he was chosen by the Royal Society
to undertake a voyage to the island of St. Helena, for the purpose
of observing the transit of Venus; and in order to make the voyage
as useful as possible, Maskelyne undertook to make observations upon
the parallax of Sirius. He remained ten months at St. Helena, but the
weather hindered his observing the transit to advantage, while the
inaccuracy of his quadrant, which was of the same construction as was
then usually employed, prevented his observations on the stars from
being as conclusive as he had expected. His voyage was, however, of
great service to navigation, by promoting the introduction of lunar
observations for ascertaining the longitude; and he taught the officers
of the ship in which he was in, the proper use of the instruments as
well as the mode of making the computations.
On his return to England, Maskelyne published, in 1763, his 'British
Mariner's Guide,' the earliest of his separate publications, in
which he proposes the adoption of a Nautical Almanac according to
the plan indicated by Lacaille, after his voyage to the Cape of
Good Hope. In the same year he performed a second voyage to the
island of Barbadoes, in order to determine the rates of Harrison's
chronometers. In his report on the results of this voyage Maskelyne,
while doing justice to the works of this eminent mechanician, decided
in favour of the employment of lunar observations for determining the
longitude, strongly supporting the cause of Professor Mayer, who had
computed lunar tables for this purpose. The liberality of the British
Government, however, bestowed on Harrison the whole reward that he
claimed,[22] while Maskelyne, having been appointed to the situation
of Astronomer Royal which likewise made him a member of the Board of
Longitude, was instrumental in procuring a reward of 5,000_l._ for the
family of Professor Mayer, and a compliment of 300_l._ for Euler, whose
theorems had been employed in the investigation.
When the merits of Mayer's tables had been fully established, the Board
of Longitude was induced to promote their application to practical
purposes by the annual publication of the Nautical Almanac, which,
during the remainder of his life, was arranged and conducted entirely
under Maskelyne's direction.
Maskelyne held the situation of Astronomer Royal for forty-seven
years, during which period he acquired the respect of all Europe, by
the diligence and accuracy of his observations, which he always, if
possible, conducted in person, requiring the aid of only one assistant.
Up to Maskelyne's time the observations of the Astronomers Royal had
been considered as private property; Flamsted publishing his own, while
Bradley's were very liberally bought of his family, and afterwards
printed by the University of Oxford. Dr. Maskelyne, on the contrary,
obtained leave from the British Government to have his observations
printed at the public expense under the direction of the Royal Society,
who are the legal visitors of the observatory, appointed by the royal
sign manual; and by thus causing the observations of the Astronomer
Royal to be recorded publicly, he supplied a great want which had
hitherto existed both in the English and French establishments. He also
made several improvements in the arrangement and employment of the
instruments used in the observatory, particularly, by enlarging the
slits through which the light was admitted; by making the eyeglass of
his transit telescope moveable to the place of each of the wires of the
micrometer; and above all, by marking the time to tenths of a second, a
refinement which had never been attempted before.
Maskelyne received his doctor's degree in the year 1777, he also
obtained the rare distinction of being made one of the eight foreign
associates of the French Academy of Science. In consequence of an
unsuccessful attempt made by Bouguer to measure the local attraction
of a mountain in South America, Maskelyne determined, in 1772, to
ascertain that of Schehallien in Scotland; and this latter undertaking,
together with the determination of the lunar orbit from observation,
and its application to navigation, may be considered as his most
important contributions to the cause of science.
In character Dr. Maskelyne was modest and somewhat timid in receiving
the visits of strangers, but his ordinary conversation was cheerful
and often playful, with a fondness for point and classical allusion.
He inherited a good paternal property, and obtained considerable
preferment from his college; somewhat late in life he married the
sister and co-heiress of Lady Booth of Northamptonshire; his sister was
the wife of Robert Lord Clive, and the mother of the Earl of Powis. Dr.
Maskelyne died on the ninth of February, 1811, in his seventy-ninth
year, leaving a widow and an only daughter.--_Notice sur la vie et les
travaux de M. Maskelyne par Delambre._ London, 1813.--_Memoir by Dr. T.
Young, Encyclopædia Britannica._
HENRY MAUDSLAY.
Born Aug. 22, 1771. Died Feb. 14, 1831.
This distinguished mechanical engineer was descended from an eminent
Lancashire family, who trace back their origin as far as the year 1200.
His father in early life enlisted in the Royal Artillery at Norwich,
and afterwards became store-keeper at the Royal Dockyard of Woolwich,
where his son Henry was born and spent his boyhood, acquiring in the
dockyard the first rudiments of that mechanical knowledge which has
since made him so justly celebrated.
After being employed for two years as a 'powder monkey' in the
dockyard, that is, in making and filling cartridges, Maudslay was
placed, at the age of fourteen, in the carpenter's shop. He however
infinitely preferred the blacksmith's shop, availing himself of every
opportunity to escape from his proper place, and steal off to the
smithy. His propensity was in fact so strong that it was thought better
to yield to it, and he was accordingly removed there in his fifteenth
year. He now made rapid progress, and soon became so expert a smith
and metal-worker as to attract considerable notice. Even in after
life, when at the head of the well-known firm which he founded, nothing
pleased him more than to set to work upon a difficult piece of forging
and to overcome the difficulties which it presented, which few could do
so well as he. The reputation which Maudslay acquired here, led to his
introduction and ultimate employment by Bramah, who was at that time
engaged in constructing his celebrated lock.
One of the chief obstacles which Bramah had to contend with in getting
his lock into general use, was, the difficulty he experienced in having
it manufactured with sufficient precision and at such a price as to
render it an article of successful commerce. Maudslay's[23] ability as
a workman and sound mechanical knowledge was of great service to Bramah
in this particular; the most difficult and delicate jobs were entrusted
to him, and among others he constructed the identical lock, the picking
of which so severely tested the skill and ability of Mr. Hobbs in the
year 1851. He also, according to the testimony of Mr. J. Nasmyth,
supplied Bramah with the key to the practical success of the hydraulic
press, viz., the self-tightening leather collar.[24]
About the year 1797 Maudslay commenced business on his own account
in Wells Street, Oxford Street, removing a few years afterwards to
Margaret Street, Cavendish Square. Here he matured and carried out many
improvements in tools connected with the mechanical arts, bringing
into general notice and use planing machines and the slide rest. So
great was the prejudice felt against this last named important adjunct
of a lathe, that on the first introduction of the slide rest to the
engineers of the period, it was received with great disfavour, and
called by one in derision the 'Go Cart.' Maudslay also directed his
attention to the subject of screw cutting. Previous to his time the
tools used for making screws were of the most rude and inexact kind:
each manufacturing establishment made them after their own fashion,
and no system was observed as to the pitch. Every bolt and nut was a
speciality in itself; and to such an extent was this carried that all
bolts and their corresponding nuts had to be marked, any mixing of
them together causing endless trouble and confusion. Maudslay changed
all this--he brought screw-cutting into a proper system, and laid the
foundation of all that has since been done in this important branch
of machine-construction, and many of those who afterwards became
eminent in this particular branch of manufacture, acquired their first
knowledge of the subject in his employ.[25] While residing in Margaret
Street he became acquainted with Sir Isambard (then Mr.) Brunel, who
was in the habit of bringing drawings of small pieces of machinery
for him to construct: this attracted Maudslay's attention, and at last
he one day exclaimed to Sir Isambard, "Ah! I see what you are thinking
of--you want machinery for making blocks:" this so pleased Brunei,
that he became more open of communication, and in the subsequent
completion of the beautiful block machinery afterwards erected at
Portsmouth Dockyard, Mr. Brunel derived great advantage from the sound
mechanical knowledge of Maudslay. The friendship commenced thus was
never afterwards shaken, and when Brunel began the Thames Tunnel, he
consulted his old friend relative to the construction of the shield, as
it was termed, under shelter of which the excavation beneath the bed of
the river, and the brickwork for forming the Tunnel were proceeded with.