154 Obituary Notices of Fellows deceased. 



an extraordinary degree, and it was rare indeed that a thought or a 

 difficulty could be presented to him over which he had not at some 

 period previously brooded. If it were not so, if the ideas were 

 really then presented for the first time, his quickness in seizing them 

 was miraculous. It is easier to suppose that during his long and 

 strenuous course of reading, and in the stimulating mental 

 atmosphere of Trinity College, in conversation also with his uncle 

 Dr. Johnstone Stoney and others, nearly all the problems in physics 

 likely to occur to contemporaries had in some form or other come 

 within his ken : and hence hardly anything that could be suggested 

 seemed altogether new and strange to him. Nor did his knowledge 

 seem to have sunk into any kind of oblivion ; there it was always 

 accessible, and with an added commentary of his own quite ready, 

 to the surprise and delight of those who conversed with him. 



So, for instance, occurred his perception of the influence of light- 

 pressure in Astronomy ; also of the emission by the Sun of electrified 

 particles which streaming past the earth might give rise to magnetic 

 storms and auroras, before our knowledge of electrons made this idea 

 easy or quantitatively feasible. So also occurred that brilliant 

 suggestion of the change of shape or distortion due to motion 

 through ether, now known as the FitzGerald-Lorentz hypothesis, 

 which flashed on him in the writer's study at Liverpool as he was dis- 

 cussing the meaning of the Michelson-Morley experiment. Of this 

 nature also was his suggestion to utilise the oscillatory discharge 

 of a Leyden jar as a means of exciting ether waves : an idea which 

 roughly had occurred to others before (the writer finds it in one 

 of his own note-books of date 1879 80), but with FitzGerald it 

 became quickly definite, leading him to investigate not merely the 

 easy problem of the wave-length to be expected, but the much more 

 difficult question of the amount of power that would be radiated by 

 an alternating current in any given case. 



Directly Hertz's experiments were published, FitzGerald discerned 

 their whole significance, and in his brilliant Presidential address to 

 Section A of the British Association, at Bath, called the world's 

 attention to them in an unmistakable manner. Had it not been for 

 the English recognition they received it is improbable that the work 

 of Hertz would have been hailed with the immediate chorus of 

 universal approbation which it commanded, for the work of his own 

 countrymen had mainly laid on other lines ; and even to Hertz 

 himself the theory of Clerk Maxwell only gradually, and subsequently 

 to his verifying experiments, became quite clear and familiar. Un- 

 doubtedly FitzGerald recognised more vividly than Hertz himself at 

 that time the full import of his experiments, the German title of 

 which was far from representing the plain significance of the title 



