168 The Aether as an Elastic Solid. 



who silently acquiesced when his discoveries were attributed to 

 others, and allowed his name to perish entirely from Cambridge 

 tradition. 



A few years before Green published his first paper, a 

 notable revival of mathematical learning swept over the 

 University ; the fluxional symbolism, which since the time of 

 Newton had isolated Cambridge from the continental schools, 

 was abandoned in favour of the differential notation, and the 

 works of the great French analysts were introduced and 

 eagerly read. Green undoubtedly received his own early 

 inspiration from this source ; but in clearness of physical 

 insight and conciseness of exposition he far excelled his 

 masters ; and the slight volume of his collected papers has 

 to this day a charm which is wanting to the voluminous 

 writings of Cauchy and Poisson. It was natural that such an 

 example should powerfully influence the youthful intellects of 

 Stokes who was an undergraduate when Green read his memoir 

 on double refraction to the Cambridge Philosophical Society 

 and of William Thomson (Kelvin), who came into residence two 

 years afterwards.* 



In spite of the advances which were made in the great 

 memoirs of the year 1839, the fundamental question as to 

 whether the aether-particles vibrate parallel or at right angles 

 to the plane of polarization was still unanswered. More light 

 was thrown on this problem ten years later by Stokes's inves- 

 tigation of Diffraction.f Stokes showed that on almost any 

 conceivable hypothesis regarding the aether, a disturbance in 

 which the vibrations are executed at right angles to the plane 

 of diffraction must be transmitted round the edge of an opaque 

 body with less diminution of intensity than a disturbance whose 

 vibrations are executed parallel to that plane. It follows that 

 when light, of which the vibrations are oblique to the plane of 



*It was in the year Thomson took his degree (1845) that he bought, and read 

 with delight, the electrical memoir which Green had published at Nottingham in 

 1828. 



f Trans. Camb. Phil. Soc., ix (1849), p. 1. Stokes's Math, and Phys. Papers, 

 ii, p. 243. 



