74 



MATHEMATICAL AND PHYSICAL SCIENCE. 



[Diss. VI. 



(334.) 

 His Me- 



Sound 



practical 



views. 



of taking part in the actual execution of scientific 

 designs ; of studying foreign languages ; and of 

 methodizing his knowledge for the purposes of in- 

 struction. Every one of these influences may be 

 clearly traced in his writings, which will challenge 

 comparison with those of any English writer, except 

 perhaps Dr Thomas Young, for variety and fulness 

 of information, and for the general soundness and 

 strongly practical character of the mechanical know- 

 ledge with which they abound. They would also 

 doubtless have appeared to far greater advantage had 

 they been the product of his most vigorous days ; but 

 he was little known as a writer until the year 1793, 

 when he commenced a series of important contribu- 

 tions to the Encyclopedia firitannica, embracing 

 at least forty- six articles, all scientific, some of great 

 length and elaboration, which were published during 

 the succeeding eight years, a period when he was seri- 

 ously afflicted with chronic disease. They embraced 

 disquisitions on general philosophy, as in the articles 

 Philosophy and Physics ; of strict science, as in 

 Astronomy, Dynamics, Projectiles, Pneumatics ; of 

 the more experimental sciences, as in Magnetism, 

 Electricity, Sound ; of the art of music (with which 

 he was practically conversant), in Temperament. 

 Piano, &c. ; but his great strength lay in the ar- 

 ticles in which just mechanical principles were ap- 

 plied successfully, and often with marked originality, 

 to practice, as in Arch, Roof, Carpentry, and Strength 

 of Materials ; Resistance, Rivers, and Waterworks ; 

 Seamanship, Steam and Steam-Engine ; Machinery, 

 Telescope, and Watchwork. 



The last-named articles (most of which have been 

 collected in a compilation, edited by Sir David 

 Brewster in four tnict v l um es, entitled RoU- 

 gon i s Mechanical Philosophy} constitute a body 

 of knowledge in civil engineering which has not 

 yet been surpassed in clear exposition of physi- 

 cal principles and their application in the ex- 

 tensive acquaintance it shows with the details of 

 practice and in proofs of elaborate and impar- 

 tial study of authors, both British and foreign, on 

 the subjects of which it treats. Several of these 

 articles have been resorted to by the most accom- 

 plished engineers of our own time as stores of sound 

 experience, and they have been lavishly borrowed from 

 by some writers on similar subjects, occasionally with- 

 out acknowledgment. The original matter which 

 they contain is not always easily separated from that 

 which is compiled. In every instance Dr Robison 

 lajs claim to less than his own share, and is so 

 scrupulous in quoting the names of other authors, 

 that he has unquestionably received less reputation 

 from these Essays than he deserves. He writes like 

 has himself used the saw and hammer, 



a man 



who has had the responsibility of success or failure, 



who might have been called upon for a scientific 

 opinion (of far more weight than what generally goes 

 by the name) on almost any practical subject upon 

 which he might have been consulted ; and that not 

 merely in its general outlines, but in its strictest de- 

 tails ; not only the design for a roof or a centre, 

 but the scantling of the timber to be used ; the mi- 

 nutiae of a pump or hot-air stove ; the curvatures of 

 an achromatic object-glass ; the temperament of a 

 piano ; or the angle for the pallets of an escapement. 

 In such matters nothing important either in the 

 theory or the practice of his times escaped him. His 

 opinions were very generally formed on original con- 

 siderations, supported by experiments equally well 

 devised and carried out. His method of finding 

 mechanically the relation between the intrados and 

 extrados of a properly balanced arch by means of 

 suspended pieces of chain is as ingenious as it is 

 elementary ; but his observations on the manner in 

 which stone arches, when overloaded, break up, es- 

 tablished on direct observation and experiment, un- 

 questionably gave a just foundation to the theory 

 of masonry, till then so generally and erroneously 

 treated of by mathematicians wit]j the preposterous 

 abstraction of the forces of friction and cohesion, 

 the action of which in many instances vastly exceeds 

 the direct effect of gravity. 



But on this we must not dwell. Robison's articles (335.) 

 on Electricity and Magnetism are deserving of nearly Writings 

 equal praise with reference to the state of knowledge ic e it ec 

 of the time. Probably there was not one author of magnetisi 

 merit on these subjects, whatever his country or lan- 

 guage, whose works he had not laboriously consulted 

 and analysed the conclusions ; whilst a multitude of 

 ingenious experiments give evidence of the skill and 

 patience of the writer. To Dr Robison we are, indeed, 

 indebted for the approximate knowledge of the pri- 

 mary law of electric attractions and repulsions ; for 

 a careful consideration of those beautiful curves 

 formed by iron filings round magnets, 1 to which such 

 an enlarged importance has since been given by the 

 beautiful generalizations of Mr Faraday ; and I be- 

 lieve likewise for the first suggestion of combining 

 the voltaic elements in a pile or column. 2 Dr Robi- 

 son, though for many years secretary of the Royal 

 Society of Edinburgh, published little in its Transac- 

 tions, and almost nothing, so far as I am aware, in 

 any periodical work. Hence his admirable adapta- 

 tions of experiments were little known beyond his 

 own class and friendly circle. 



Of his more abstract mathematical writings we (336.) 

 need say little. He was thoroughly acquainted with ^ 1S exter 

 the works and methods of Newton, and with nearly . an(1 

 all those of the same school, particularly of Bos- mathe- 

 covich. He laboured incessantly to reduce the de- matical a 

 monstrations of the higher mechanics and astrono- c l uir *~ 



1 Indirectly we owe to him also the first exact determination of the mathematical properties of these curves, made at his 

 request by Mr Playfair. Robison'e Aleck. Phil., iv. 350. 

 a See the Fifth Dissertation (by Sir John Leslie), p. 739. 



