PLAYFAIK. 95 



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 

 ' Encyclopaedia Britannica' an introductory ' Dissertation on the 

 Progress of Mathematical and Physical Science,' a treatise distin- 

 guished for the soundness of judgment, beauty of writing, and ex- 

 tent 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 atten- 

 tion 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 severity 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 

 1 JEpinus' and ' Physical Astronomy,' in the ' Encyclopaedia Britan- 

 nica.' 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^ 

 ly Lord Jeffrey. Encyclopedia Britannica. 



