Chapter V: Part 5

On his return to England, he qualified himself to serve on the general 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.

In the year 1807 Maudslay took out a patent for improvements in the steam-engine, by which he much simplified its parts and secured greater directness of action. His new engine was called the Pyramidal, from its form, and was the first move towards direct acting engines. In 1810, finding his business getting too extensive for his premises in Margaret Street, he removed to the more capacious ones in Westminster Road, Lambeth. Here he for many years carried on a large business, embracing the manufacture of all kinds of machinery, but more particularly of marine engines, to the construction and improvement of which he early directed his attention, foreseeing how important a branch of industry they would eventually become; and it may be interesting to record, that the engines (24 H. P.) of the 'Regent,' the first steamboat which ran between London and Margate, were made at this yard in the year 1816.

Mr. Maudslay held for several years the contract for supplying the Royal Navy with ship tanks, and this led to his making improved machinery for punching and shearing the iron plates used in their manufacture, reducing the cost of preparing the plates for receiving the rivets from seven shillings, to ninepence, per Tank.

Mr. Maudslay has been described by his friend Mr. James Nasmyth as the very beau-ideal of an honest, upright, straightforward, hardworking intelligent Englishman: he died in his 60th year from a severe cold which he had caught on his way home from a visit to France, and was buried in Woolwich churchyard, in a vault he had caused to be constructed there; the monument and tablet erected to his memory were of cast iron, and were made from a design of his own. Maudslay married when twenty years old Sarah Tindel, by whom he had four sons and three daughters, of whom now survive only one daughter, and one son Thomas Henry Maudslay.--_From particulars communicated by members of the present firm of Maudslay, Sons and Field._--_Smile's Industrial Biography._ London, 1863.

PATRICK MILLER.

Born in Scotland 1730. Died at Dalswinton House, near Dumfries, 1815.

Patrick Miller, of Dalswinton, was originally a banker, and ultimately became possessed of considerable independent property. At different periods of his life he embarked in many schemes of great public utility. He made considerable improvements in artillery and naval architecture, and during the course of his various experiments expended upwards of thirty thousand pounds. One of the immediate results of his experiments in the first-named science was the invention of the well-known carronade; while in the course of his experiments in naval architecture, he constructed double and triple vessels, and was the first to practically apply the present form of the paddle-wheels now in ordinary use to their propulsion. Having satisfied himself of the usefulness of his researches in this respect, by many costly experiments undertaken at his own expense, Mr. Miller published at Edinburgh, in 1787, a book in English and French, containing a full account of them, and sent a copy of his work to every sovereign in Europe, and also to the American States, inasmuch as he considered that his inventions ought to be the property of the human kind.[26] The paddle-wheels in these experiments (undertaken in the years 1786-7) were turned by manual labour, and on the occasion of a severe contest between one of his double boats and a Custom-house boat, reckoned to be a fast sailer, the want of a more powerful force to turn the wheels was greatly felt. Mr. James Taylor, at that time a tutor in Mr. Miller's family, suggested steam power, and ultimately introduced Miller to Wm. Symington, with whose aid Mr. Miller commenced and carried out those experiments (in the years 1788-89) which have justly entitled him to the honour of being the first to originate the present system of steam navigation.[27]

It is much to be regretted that since the deaths of Mr. Miller and Mr. Symington, statements have been made in which the _entire_ merit of first establishing steam navigation is claimed, on the one hand, for Miller, by his eldest son, in a paper published in the 'Edinburgh Philosophical Journal' for July 1825; and on the other for Symington, by Richard Bowie, in his pamphlet published in 1833; whereas these two gentlemen appear to be inseparably connected with the first introduction of this grand application of steam. As far as it is possible to reconcile the conflicting statements, the facts may be briefly stated thus. Patrick Miller was the first to successfully propel vessels by paddle-wheels moved by manual labour. He then, in conjunction with William Symington, applied steam to move these paddle-wheels, and constructed two steam-boats, which were publicly tried, on the Forth and Clyde Canal, in the years 1788-89. Although these trials triumphantly proved the practicability of steam navigation, further improvements were required before a really successful steam-boat could be said to have been constructed. At this point, unfortunately, Mr. Miller, having already spent large sums of money in his experiments, let the matter drop; but Symington, about ten years afterwards, under the patronage of Lord Dundas, succeeding in constructing 'The Charlotte Dundas,' a steam-boat which, for the first time, combined together those improvements which constitute the present system of steam navigation. In the narrative written by Patrick Miller, Jun., a good deal of praise, in regard to this matter, is given to James Taylor, before referred to, who is considered by some as having a just claim to participate in the honour awarded to Miller and Symington. Mr. Taylor's merits, however, appear chiefly to consist in having suggested, upon the occasion of a race between one of Miller's boats and a Custom House boat, that they only required the help of a steam-engine to beat their antagonists; also, in having introduced Symington, whose steam-carriage had rendered him famous, to the notice of Mr. Miller; and although Taylor assisted in the subsequent experiments, he seems to have contributed little to their practical success.--_Narrative of Facts relative to Invention and Practice of Steam Navigation, &c., by Patrick Miller, Jun., 'Edinburgh Philosophical Journal,'_ Vol. 13, July 1825.--_Narrative by R. Bowie, proving William Symington the Inventor of Steam Land Carriage Locomotion and of Steam Navigation._ London, 1833.--_Stuart's Anecdotes of the Steam Engine._ London, 1829.--_Descriptive Catalogue of the Museum of the Commissioners of Patents._

WILLIAM MURDOCK.

Born 1754. Died November 15, 1839.

William Murdock was born at Bellow Mill, near Old Cumnock, Ayrshire, where his father carried on the business of a millwright and miller, and likewise possessed a farm on the estate of the Boswell family of Auchinleck. His mother's maiden name was Bruce, and she used to boast of being lineally descended from Robert Bruce, of Scottish History. Little is known of Murdock's life prior to his coming to England, and joining, in the year 1777, Boulton and Watt's establishment at Soho, at that time in its infancy. He must, however, have had some celebrity in his native country, as he was employed to build a bridge over the river Nith, in Dumfrieshire, a very handsome structure, and still in existence. His talents were soon appreciated at Soho, particularly by James Watt, with whom he continued on terms of the closest friendship until Mr. Watt's death in 1819. After remaining two years at Soho, Murdock was appointed by Messrs. Boulton and Watt to superintend the erection, and undertake the general charge, of their new steam-engines in Cornwall, where he erected the first engine, in that part of the country, with a separate condenser. He continued to live in the district for the space of nineteen years, giving great satisfaction to the mining interest; so much so, that when it became known that he was about to return to Soho, 1000_l._ a-year was offered him to remain in Cornwall. During his residence there Murdock contrived and executed a model locomotive, which, as early as the year 1784, he was in the habit of showing to his friends in working order, and drawing a small waggon round a room in his house at Redruth. He used to tell a story, that while making experiments with this engine, he one night determined to test its powers on a level road leading from his house to the church, which was situated about a mile distant from the town; this road was bounded on each side by high edges, and well suited for the purpose. Murdock accordingly sallied out, and placing his engine on the ground, lit the fire, or rather lamp, under the boiler; after a few minutes off started the locomotive with the inventor full chase after it; after continuing the pursuit for a short distance, he heard cries as of a person in great distress; the night was too dark to perceive objects afar off, but on going on, he found that the sounds proceeded from the clergyman of the parish, who had set out for the town on business, and being met on this lonely road by the fiery monster, had taken it for the Evil One in person. This model locomotive was exhibited before a meeting of the Institution of Mechanical Engineers in 1850, sixty-six years after the date of its construction.

Mr. Murdock is, however, better known to the public by his application of the light of coal gas to general purposes. Although this gas had been well known, and obtained both naturally and artificially more than half a century before his time, no attempt had as yet been made to turn the discovery to any useful account. In the year 1792 Murdock first employed coal gas for the purpose of lighting his house and offices at Redruth; he made it serve also as a lantern, by attaching a bladder with a tube mouthpiece under the bottom of a glass shade, which contrivance used to light him across the moors when returning home at night from the mining engines he was erecting in different parts of the district. After various experiments which proved the economy and convenience of light so obtained, he perfected his apparatus and made a public exhibition of it by lighting up the front of Boulton and Watt's manufactory at Soho, on the occasion of the general illumination for the peace of Amiens, in 1802. He subsequently lighted up some cotton mills at Manchester, beginning with Messrs. Phillips and Lee's, and published a paper on the subject in the 'Philosophical Transactions' of 1808, for which the Royal Society presented him with the Rumford gold medal.

In 1798 Murdock returned to take up his permanent residence at Soho, superintending the machinery there, and occasionally the erection of engines at a distance, among which may be mentioned those of the New River Head, Lambeth, Chelsea, Southwark, East London, West Middlesex, and other waterworks. In the following year he took out a patent for improvements in boring cylinders and in the manufacture of steam casings; this patent also included the double =D= slide valve and a rotary engine. Amongst other inventions and discoveries of Murdock's are: a plan for boring stone pipes for water, and cutting columns out of solid blocks of stone (for which he took a patent in 1810); a pneumatic lift working by compressed air; and a cast iron cement, which he was led to discover by the accidental observance of some iron borings and sal-ammoniac, which had got mixed in his tool-chest and rusted a sword blade nearly through. He also made use of compressed air to ring the bells in his house; a plan which so pleased Sir Walter Scott, to whom it had been described, that he had his house at Abbotsford fitted up in a similar manner. Murdock likewise discovered a substitute for isinglass, and when in London for the purpose of explaining to the brewers the nature of his discovery, occupied very handsome apartments. Being, however, at all times absorbed in whatever subject he had in hand, he little respected the splendour of his drawing-room, but proceeded with his experiments as if in the laboratory at Soho, quite unconscious of the mischief he was doing. This resulted in his abrupt dismissal from the apartments by the enraged landlady, who one morning, on calling in to receive orders, was horrified at seeing all her magnificent paper-hangings covered with wet fish skins hung up to dry, and actually caught him in the act of pinning up a cod's skin to undergo the same process.

In the year 1815, while Mr. Murdock was fitting up an apparatus of his own invention for heating the water of the baths at Leamington, a ponderous cast-iron plate fell upon his leg above the ankle, nearly severing it in two. This severe accident laid him up for a long time, and he never entirely recovered from the effects of it. During the latter years of his life Murdock's faculties, both corporeal and mental, experienced a gradual decay, causing him to live in complete retirement. He died in 1839, aged eighty-five years, and his remains were buried in Handsworth Church, near to those of Boulton and James Watt.

Mr. Murdock married in the year 1785 the daughter of Captain Paynter, of Redruth, Cornwall, who died at the early age of twenty-four, having had four children.--_From a Paper read by Mr. William Buckle, of Soho, before a meeting of the Institution of Mechanical Engineers_, October 23, 1850.

ROBERT MYLNE.

Born January 4, 1733. Died May 5, 1811.

Robert Mylne, the architect of Blackfriars Bridge, was born at Edinburgh. His father was an architect, and magistrate of the city; and his family, it has been ascertained, held the office of Master Masons to the Kings of Scotland for a period of five hundred years, until the union of the crowns of England and Scotland.

On arriving at man's estate, Mylne travelled for improvement; and his enthusiastic prosecution of his art soon brought him into notice. In 1758 he became a candidate for the honours of the Academy of St. Luke at Rome, and the chief prize in the highest class of architecture was awarded to him; being the first instance of a native of Great Britain obtaining that honour.

Mylne resided at Rome during a space of five years, and on his return to England executed a design for Blackfriars Bridge, which was selected from among twenty others. This bridge was commenced in 1760; and on the occasion of the laying of the foundation-stone by the Lord Mayor, among other medals deposited in the stone was a silver one, the memorial of the young architect's first triumph, viz., the medal (one of two) given him by the Academy at Rome. The bridge was completed in 1769; the arches are elliptical in shape, and were the first instances in England in which the form of an ellipse was substituted for a semicircle. The total cost of the bridge itself, exclusive of the approaches, amounted to 152,840_l._

Mylne's reputation was now established, and his services were employed in the erection or improvement of many edifices throughout the United Kingdom. He received at the hands of the Archbishop of Canterbury, the Bishop of London, and the Lord Mayor, the office of Surveyor of St. Paul's Cathedral; and while holding this appointment, suggested the famous inscription to Sir Christopher Wren--'_Si monumentum quæris circumspice_.' He also held the office of Clerk of the Works at Greenwich Hospital for fifteen years, and was Engineer to the New River Water Works from the year 1762 until his death, in 1811, when he was succeeded by his son.

Towards the close of the eighteenth century, he became acquainted with Mr. John Rennie, whose celebrity as an engineer was then approaching its height; and the two became from that time inseparable friends.[28] Mr. Mylne was also an intimate friend of Dr. Johnson, their acquaintance having originated out of a controversy as to the form of the arch for Blackfriars Bridge.

Mylne was buried in St. Paul's Cathedral, by the side of his illustrious predecessor, Sir Christopher Wren.--_Gateshead Observer_, October 20, 1860.--_Encyclopædia Britannica._

ALEXANDER NASMYTH.

Born September 7, 1758. Died April 10, 1840.

Alexander Nasmyth, the distinguished Scotch landscape painter, and known also as a man of science, was born at Edinburgh. He came early in life to London, where he was for some time the pupil of Allen Ramsay, painter to George III. He resided afterwards in Rome for several years, during which time he studied portrait, history, and landscape painting.

From Rome, Nasmyth returned to Edinburgh, where he settled as a portrait painter, and executed his well-known painting of Robert Burns-the most authentic likeness of this great poet. Having, however, a decided taste for landscape painting, he ultimately confined himself to this branch of art; but much of his time was occupied in teaching, in which he was very successful. His landscapes, which are very numerous, were, many of them, reminiscences of Italian scenery, and although wanting in originality and vigour, possess so much beauty and grace as to have caused their author to acquire the name of the 'Scottish Claude.'

Mr. Nasmyth was a favourite in society, and was the leading teacher in art of the highest classes in Scotland; during his later years being commonly looked up to as the patriarch of Scottish art. He not only took much interest in the proceedings of the artistic societies of Edinburgh, but often raised an influential voice in respect to the alterations making in that city; and was one of the three successful competitors between whom the first prize offered for the best plan for laying out and building the New Town of Edinburgh was equally divided.

Mr. Nasmyth spent much of his time in scientific experiments, and was the inventor of 'bow and string bridges,' and of a method of driving the screw-propellers of vessels by direct action, in front of the rudder. Much of his leisure time was spent in a workshop which he had fitted up for himself, and which proved the nursery of the early mechanical genius of the present James Nasmyth, the celebrated engineer.

Soon after his return from Italy, Alexander Nasmyth married the sister of Sir James Foulis of Woodhall Colinton, by whom he had a family of three sons and five daughters, all of whom inherited more or less their father's talents, while the eldest, Patrick, has acquired a separate renown of no inconsiderable extent, for the beauty of his landscapes.

Alexander Nasmyth died in York Place, Edinburgh, at the age of eighty-three, and was interred in the West Church burying-ground of that city.--_English Cyclopædia._ London, 1857.--_Catalogue of Gallery of Portraits of Inventors, &c., in the South Kensington Museum._

JOHN PLAYFAIR, F.R.S., L. and E.

PROFESSOR OF MATHEMATICS AT THE UNIVERSITY OF EDINBURGH.

Born March 10, 1748. Died July 19, 1819.

John Playfair, a mathematician and philosopher of great eminence and celebrity, was born at Benvie in Forfarshire, and was the eldest son of the Rev. James Playfair, the minister of that place. Playfair resided at home, under the domestic tuition of his father, until the age of fourteen, when he entered the University of St. Andrew's, where he became almost immediately distinguished, not merely for his singular proficiency in mathematical learning, but also for the extent of his general knowledge, the clearness of his judgment, and the dignity and propriety of his conduct. A strong proof of his capabilities at this time is given by the fact, that when Dr. Wilkie, the professor of natural philosophy, was prevented by indisposition from delivering the regular lectures, he used generally to delegate the task of instruction to his youthful pupil, Playfair.

In 1769 Playfair removed to Edinburgh, and while residing there became acquainted with Adam Smith, Drs. Robertson, Matthew Stewart, Black, and Hutton, with all of whom he continued on terms of the utmost cordiality during the whole period of their lives.

During the course of the year 1772, the death of his father suddenly devolved upon Playfair the burden of supporting his family, and compelled him in a measure to seek a livelihood by entering the Church. Although he had been educated with a view to his entering this profession, for which he was in every way qualified, his decided predilection for science had hitherto made him hesitate about engaging in a vocation, the duties of which, he felt, if conscientiously discharged, would necessarily interfere greatly with the studies he was loath to abandon. In this emergency, however, he considered himself no longer entitled to indulge in these predilections, and therefore made an application, which proved successful, to Lord Gray, the patron, for a presentation to the livings of Liff and Benvie, which had been previously held by his father. From this period until 1782, he was constantly resident at Liff, occupied almost exclusively with the pastoral duties of his office, and with the education of his younger brothers.

In the year 1779 Playfair contributed to the 'Transactions' of the Royal Society of London a paper on the 'Arithmetic of Impossible Quantities,' which exhibits, within a very small compass, a striking example of the rare and admirable talent of detaching the sound spirit of science from what may be termed its mysticism. In the year 1782 he was induced by very advantageous offers to resign his charge, and to superintend the education of Ferguson of Raith, and his brother Sir Ronald; an arrangement which restored him in a great measure to the literary and scientific society of Edinburgh, and enabled him to visit London, where he was gratified by a personal introduction to several of the most eminent cultivators of science in that city.

Playfair was received into the University of Edinburgh during the course of the year 1785, and, in consequence of an arrangement made between Dr. Adam Ferguson and Mr. Dugald Stewart, was appointed joint-professor of mathematics with Dr. Ferguson, whose delicate state of health prevented him from discharging the active duties of the professorship; Mr. Stewart filling the chair of moral philosophy, previously held by Dr. Ferguson.

Previous to this, like Leslie, Playfair had been twice a candidate for a similar honour, but unsuccessfully. On the first occasion, when only eighteen years old, he had offered himself, with the approbation of his instructors at St. Andrew's, as candidate for the professorship of mathematics in Marischal College, Aberdeen, and had sustained with much credit a competitive examination which lasted eleven days, and embraced nearly the whole range of the exact sciences. Out of six competitors, two only were judged to have surpassed him--the Rev. Dr. Trail, who was appointed to the office, and Dr. Hamilton, who afterwards succeeded to and long filled it with much reputation.

In 1788, Playfair published, in the 'Transactions' of the Royal Society of Edinburgh, a biographical account of Dr. Matthew Stewart, which also contains a singularly clear and interesting account of the labours of Dr. Simson in the restoration of ancient geometry. In this year likewise appeared his paper 'On the Causes which affect the accuracy of Barometrical Measurements,' which is written with all the perspicuity, caution, and sagacity, that constitute the great excellence and the great difficulty of such disquisitions, where scientific principles are employed to give precision to physical observations. In 1790 appeared, in the same 'Transactions,' a paper of still greater interest and delicacy, 'On the Astronomy of the Brahmins,' the publication of which attracted very general attention, both in Europe and in Asia, and gave rise to much discussion and research. This was followed in 1794 by a learned and very beautiful treatise on the 'Origin and Investigation of Porisms,' in which the obscure nature of the very comprehensive and indefinite theorems to which this name was applied by the ancient geometers, is explained with the most lucid simplicity.

In 1797 he composed a sequel to his first paper on the Indian astronomy, in the shape of 'Observations on the Trigonometrical Tables of the Brahmins,' and also a masterly collection of 'Theorems on the Figure of the Earth.' During the course of the last-mentioned year, his friend Dr. James Hutton died; and Playfair, having undertaken to draw up a biographical account of him for the Royal Society, was led to study the doctor's ingenious but crude speculations on the 'Theory of the Earth,' and afterwards to lend them the assistance of his own powerful pen, in his 'Illustrations of the Huttonian Theory.' This work, upon which he bestowed more time and labour than on any of his other productions, did not appear until 1802; and whatever opinion may be formed of the truth or soundness of Dr. Hutton's speculations, it is impossible to doubt that Playfair's illustration of that theory must always be ranked amongst the most brilliant and powerful productions of philosophical genius. Its merits have been universally acknowledged, even by those not convinced by its reasonings, and have extorted, even from the fastidious critics of France, the acknowledgment that "Mr. Playfair writes as well as Buffon, and reasons incomparably better."

In 1805 he quitted the chair of mathematics to succeed Professor Robison in that of natural philosophy. In the contest which ensued upon the appointment of Leslie as his successor in this chair, he took a very active part; and amongst the heaviest blows which Leslie's opponents had to sustain, were those that parted from the hand of Mr. Playfair. In 1807 he was elected a Fellow of the Royal Society, to which learned body he very soon afterwards presented his 'Account of the Lithological Survey of Schehallien;' this was the result of his investigations during the period of Dr. Maskelyne's visit to Schehallien, to measure the attraction of that mountain, on which occasion Playfair shared the shelter of this distinguished astronomer's tent on the side of the mountain, and contracted with him a friendship which lasted during the remainder of their lives.

In 1809 he contributed to the 'Edinburgh Transactions' an excellent paper on 'Solids of the Greatest Attraction,' and in 1812, another, on the 'Progress of Heat in Spherical Bodies.' In 1814 he published, in two volumes octavo, for the use of his class, an elementary work of great value, under the title of 'Outlines of Natural Philosophy.' About the same time he drew up for the 'Encyclopædia Britannica' an introductory 'Dissertation on the Progress of Mathematical and Physical Science,' a treatise distinguished for the soundness of judgment, beauty of writing, and extent of knowledge displayed in it. In 1815, Playfair wrote for the Royal Society of Edinburgh a very interesting memoir of his distinguished predecessor, Dr. Robison. In the course of the same year he undertook, at the age of sixty-eight, a long journey through France and Switzerland into Italy, and did not return for a period of nearly eighteen months, during which time his principal attention was directed to the mineralogical and geological phenomena of the different regions which he visited. On his return from this expedition, he was occupied in drawing up a memoir on the 'Naval Tactics of Clerk of Eldin,' which was published after his death in the 'Philosophical Transactions.'

Playfair had for several years suffered from a recurrence at different times of a painful affection of the bladder, which appeared with increased seventy in the early part of 1819, but was so far got under as to enable him to complete his course of lectures in the spring. It returned, however, in a still more distressing form in the summer, and at last put a period to his life on the 19th of July. Though suffering great pain during the last part of his confinement, he retained not only his intellectual faculties quite unimpaired, but also the serenity and mildness of his spirit, occupying himself until within a few days of his death in correcting the proof-sheets of the 'Dissertation' before noticed.

Besides the previously mentioned works, Playfair was a frequent contributor to the 'Edinburgh Review,' and also wrote the articles 'Æpinus' and 'Physical Astronomy,' in the 'Encyclopædia Britannica.' Francis Jeffrey, of whose elaborate and elegant memoir the above is but a brief summary, speaks of Playfair as being "one of the most learned mathematicians of the age, and among the first, if not the very first, who introduced the beautiful discoveries of the later Continental geometers to the knowledge of his countrymen, and gave their just value and true place in the scheme of European knowledge, to those important improvements by which the whole aspect of abstract science has been renovated since the days of our illustrious Newton;" also, "as possessing in the highest degree all the characteristics both of a fine and powerful understanding, at once penetrating and vigilant, but more distinguished perhaps for the caution and sureness of its march than for the brilliancy or rapidity of its movements; and guided and adorned through all its progress by the most genuine enthusiasm for all that is grand, and the justest taste for all that is beautiful."--_Memoir of John Playfair, by Lord Jeffrey._--_Encyclopædia Britannica._

JOHN RENNIE, F.R.S., L. and E., &c.

Born June 7, 1761. Died October 4, 1821.