Part 16

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. 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.

John Rennie was born at Phantassie, in the parish of Prestonkirk, in the county of East Lothian. His father was a highly respectable farmer, who died in 1766, leaving a widow and nine children, of whom John was the youngest. He acquired the first rudiments of his education at the village school, which was situated on the opposite side of a brook. To cross this at certain seasons of the year it was necessary to make use of a boat, which was kept at the workshop of Andrew Meikle, an ingenious mechanic well known in Scotland as the inventor of the threshing machine. Young Rennie, having thus frequent occasion to pass through Meikle's workshop, became deeply interested in the various mechanical operations that were in progress, and a great part of his leisure and holiday time was spent therein. During the evening he employed himself in imitating the machines which had particularly attracted his attention, and when only ten years old succeeded in constructing a model of a steam-engine, a windmill, and a pile-driving machine. At twelve years of age he left the Preston school and entered the service of Mr. Meikle for a space of two years, at the end of which time, finding that a constant application to manual labour retarded the progress of his intellectual faculties, he determined to place himself under the tuition of Mr. Gibson, an eminent mathematical master at Dunbar. Here Young Rennie attained such proficiency in his studies, that when, two or three years afterwards, Mr. Gibson was appointed master to the public academy at Perth, he was able to undertake the temporary management of the Dunbar school. While at this school he attracted the especial notice of Mr. David Lock, who, in describing a visit to Dunbar, makes particular mention of him as one likely to prove an honour to his country. On leaving Mr. Gibson, Rennie returned to Mr. Meikle, continuing more or less with that ingenious man for the next two or three years. His first essay in practical mechanics was the repairing of a corn mill in his native village, and he erected two or three others before he had reached the age of eighteen. While occupied in these works Rennie took care at the same time to attend to his other studies, managing occasionally to visit Edinburgh, where he entered himself as a student at the University, and attended the lectures of Professors Robison and Black. With the former gentleman he gradually formed an intimate acquaintance, and was by him introduced to Messrs. Boulton and Watt, of Soho, with whom he remained during the space of twelve months; it being their wish to have engaged his services for a longer period, but Rennie, conscious of his own powers, determined to make the capital the theatre of his future efforts. His first practical essay at millwright work in England was the rolling mills at Soho, which were entirely remodelled and rebuilt under his direction.