On the 6th of March, 1809, Mr. Playfair submitted to the Royal Society an ingenious paper On the Progress of Heat, when communicated to Spherical Bodies from their Centres.§ This paper originated from an argument urged by the late Dr. Murray against the fundamental principle of the Huttonian theory. Although Mr. Play fair's defence w as unanswerable, Dr. Murray, who could not be supposed to appreciate the mathematical argument, replied to it at considerable length. A second and more popular paper was again read by Mr. Playfair ; but he (lid not think it necessary to strengthen his original defence by any additional illustration.
In the year 1805, Mr. Playfair laid before the Royal So ciety a Biographical Account of the late John Robison, LL.D.II and he left behind him an unfinished memoir of the late John Clerk of Eldin, the inventor of the naval tactics, which has been published in the 9th volume of the Edinburgh Transactions.
In addition to the works which bear Mr. Playfair's name, he wrote various articles in the Edinburgh Review, which he never hesitated to acknowledge, and some of which have been reprinted among his works. Of these reviews, three are particularly memorable, as indicating the pecu liar character of Mr. Playfuir's talents, as well as the great versatility of his powers. His analysis of the Illecanigue Celeste of Laplace, while it evinces the highest powers of composition, is at the same time one of the choicest spe cimens of perspicuous illustration. His review of Les lie's Geometry (the ablest, perhaps, that he ever wrote) is distinguished by a masterly argument in one of the most difficult topics of abstract mathematics, and has been no less celebrated for the force and the dignity of its The review of Madame de Stael's Corinne, in the same work, affords the clearest evidence that its author was equally fitted to shine in the field of elegant literature and in the walks of abstract science. Several other reviews from Mr. Mayfair's pen would have been entitled to notici in a more extended memoir of his life, but those already mentioned have been selected as particularly tic of his powers as a natural philosopher, a matician, and a cultivator of the lighter branch..s of lite rature.
Playfair un At the restoration of peace, in 1815, dertook a journey to the Continent, for the purpose in ex amining the stupendous phenomena presented n geology of the A ips,—of studying the recent effects volcanic eruptions in Italy, and of developing those of more ancient convulsions among the extinct volcanoes of Auvergne. Excepting the phenomena exhibited in our own island, which he had personally examined, Mr. Play lair had acquired his geological knowledge principally from books; and it was therefore desirable, before the re publication of his favourite work, that his views should receive those modifications which the study of nature in her grandest forms could not fail to suggest. With this view lie spent about seventeen months in France, Switzer land, and Italy, busily engaged in geological observations ; and he returned to Edinburgh in the end of 1816, eager to embellish and complete the great fabric which it had been the business of his life to rear.
Unfortunately, however, for the Ifuttonian School, Mr.
Playfair had been urged to draw up a dissertation on the progress of mathematics and physics for the SuppleMent to the Encyclopmdia Britannica ; and the composition of this paper, as his nephew informs us, interrupted the ex ecution of the second edition of his Illustrations.* This dissertation, the first part of which 11r. Mayfair did not live to finish, is marked with the able but now faultering hand of its distinguished author. In the 70th year of his age, and haunted with the image of his unfinished work, the drudgery of compilation must have been irksome to a mind less anxious than his, and conscious that it was ex hausting its powers on an arena where no laurels could be gained. The history of the mathematical and physical sciences had been already exhausted by the voluminous and profound labours of Montucla. The Abbe Bossut had gleaned its choicest flowers, and prepared them in nervous and simple rhetoric for the taste of less laborious students ;—and that branch of the history of physics, for which Mr. Mayfair's talents were peculiarly adapted, namely, the history of astronomical discovery, had been illustrated by the brief yet powerful narrative of Laplace, by the rich and discursive eloquence of Bailly, and by the varied and searching erudition of Delambre. A field thus preoccupied, and on which learning and genius had cast their richest offerings, was not likely to be chosen by Mr. Play fair for the display of his own powers. He undertook the task to which he bad been urged ; and that part of it which Providence allowed him to execute, he executed with his usual judgment and discrimination.
Some time after his return from the Continent, Mr. Playfair read to the Royal Society a paper on rolcanoes, which excited great interest, but which is neither men tioned in his life, nor printed along with the rest of his works. On the 3d December, 1818, he likewise commu nicated to the same body his Description of the Slide of .11pnach, which has been published as an appendix to his life. These two communications were an earnest of the stores of valuable information which he bad accumulated daring his travels, and which he meant to give to the world in a series of detached papers. His health, howe ver, had been for some time on the decline; and in the winter of 1818-1819, his labours were often interrupted by a severe attack of a disease in the bladder, which, at his advanced period of life, it was not easy to subdue. An interval of health soothed for a while the anxieties of his friends; but it was only a deceitful precursor of the fatal attack which carried him off, on the 19th July, 1819, in the 72d year of his age. The various public bodies with which lie was connected followed his remains to the grave, and testified the respect which they cherished for that rare union of worth and talents which marked the character of this much esteemed and deeply lamented philosopher.
For a fuller account of the life, writings, and character of Mr. Playfair, the reader is referred to an edition of his works published by his nephew, Dr. Mayfair, in 3 vols. Svo. and to a biographical memoir which will probably appear in the tenth volume of the Transactions of the Royal Society of Edinburgh.