TRANSACTIONS OF SECTION A. 511 



reach of their algebraic analysis; but for all that his mind was eminentlv of a 

 mathematical cast. He is never vague or loose in his reasoning, and hehad a 

 wonderfully tenacious grasp of physical principles. The result was that he has 

 succeeded in finding out the key to some of the most curious phenomena in the 

 motions of fluids. 



I may giveas a typical instance of his line of reasoning his beautiful explana- 

 tion of the action of the water of a river flowing round a bend. He saw clearly 

 that from true dynamical principles the flow of the water must be most rapid near 

 the inner bank, and the question which presented itself to his mind was why then 

 the inner bank was not worn away. The answer he showed to consist in the 

 friction of the bed checking the velocity of the lowest stratum of the water. 

 The effect of this he proves to be that an under-current is produced in this stratum 

 across the bed of the river from the outer towards the inner bank, a current 

 which does two things: it carries sand and detritus and deposits them on the 

 mner bank ; and, since the. water in this current has to rise verticallv to the 

 surface when it reaches this bank, it thus protects it from the scour. 



In a review of Thomson's work we should emphasise his constant endeavour 

 whether m Mathematics or Physics, to attain clear conceptions of fundamental 

 principles. This showed itself in the various innovations in nomenclature he 

 introduced. Many of the new words he coined, 'radian,' 'numeric,' 'torque' 

 ' interface,' ' clinure,' ' posure,' &c., are great, helps both in thinking and 'teaching.' 



The same determination at any cost of hard thinking to arrive at clearness in 

 regard to fundamental principles is strikingly evidenced by one of his later papers 

 that on the ' Law of Inertia and the Principle of Chroiiometry,' which is a most 

 searching discussion of the true significance of Newton's first and second laws of 

 motion. 



I must now close this review. I shall be glad if I have succeeded, however 

 imperfectly, in giving you some impression of our Irish schools of Mathematics 

 and Physics, of the workers and of the sources from which tliev drew their inspira- 

 tion. _ There surely never was a time when the problems presented to the mathe- 

 matician by Physical Science were more interesting ; never a time when Science 

 for its onward progress stood more in need of those gifted ones who combine 

 clearness of thought with imagination and hopeful courage. Let us hope that 

 amongst these in this new century, others of our countrymen may be found not 

 unworthy to have their names inscribed in the roll which contains those of 

 Hamilton and MacCullagh, of Andrews and Thomson. 



The following Papers were read : — 



L On the Question as to the Accurate Conservation of Weight in 

 Chemical Reactions. By Lord Rayleigh, F.E.S. 



2. Motion of a Detached Thread of Liquid in a Capillary Tube, 

 By Professor W. B. Mokton, M.A., and W. Hawthorn. 



3. On the Vibrations of a Plucked, String 

 By Professor W. B. Morton, M.A., and T. B. Vinycomb. 



4. On Continuous Motion prodxiced by Yihrations 

 By Professor W. B. SIorton, M.A., ami A. M. Kinsky. 



On the Prevention of a Deposit of Dew on the Lenses of a Projecting 

 Lantern. By Professor A. Schuster, F.R.S. 



