494 Professor A. W. Bucker [March 8, 



on sound. He invented the ophthalmoscope, by which the oculist 

 can study the inmost recesses of the eye. The theory of colour 

 vision, the theory of binocular vision, the curious subjective effects 

 which are produced when we deliberately deceive our own senses by 

 the stereoscope ; these subjects he made especially his own. 



In the field of mathematics, he was the first to define the peculiar 

 rotatory motion of a liquid known as vortex-motion. Great men 

 had laid the foundations of hydrodynamics before him, but all 

 had overlooked the importance and laws of the vortex. Since the 

 memoir of Helmholtz was published, the subject has been widely 

 studied. Lord Kelvin has originated the famous vortex-ring theory 

 of matter ; Prof. Fitzgerald has suggested that the ether may be a 

 complex of vortices, or, as it has been called, a vortex-sponge. 



On electricity he wrote much — on the theory of the galvanic cell, 

 on electrolysis, on electromagnetism. 



In England, at all events, we give the preference, as regards the 

 last subject, to the theory and writings of our own Maxwell. 



As I have already said, von Helmholtz, in an age of specialists, 

 was a universal genius. His intellect could light on nothing which 

 it did not illuminate. Hence, his opinions on side issues are of more 

 than ordinary importance, his " obiter dicta " are worth attention, his 

 popular lectures acquire a special interest. Let us for a few moments 

 turn to these. 



The watchword of Helmholtz in dealing with educational 

 problems, is " freedom." Freedom for the student, freedom for the 

 teacher. 



In England, we are fond of insisting that there are certain things 

 which everybody who aspires to academic rank must know; of 

 hedging in our students by prescribed courses of study. We make 

 them feel that general culture is an iron-bound safe, which they must 

 wrench open before they can attain the gem of real knowledge, rather 

 than a setting, without which the most profound acquirements seem 

 unattractive and dull. Yet von Helmholtz, one of the most highly 

 educated men, one of the most comprehensive geniuses of the latter 

 end of the century, will have no set courses, except as a preparation 

 for a definite profession, is proud that Germany has " retained the 

 old conception of students, as that of young men responsible to 

 themselves, striving after science of their own free will, to whom it 

 is left to arrange their own plan of studies as they think best." 

 Not content with having made the attainment of this ideal almost 

 impossible for English students, doctrinaire educationalists are now 

 beginning to throw their net around the teacher. It is claimed that 

 as the student must go through a prescribed course of study in order 

 to learn, so the teacher must be drilled and examined before he is 

 allowed to teach. Whatever can be said for this plan as regards the 

 less advanced class of teachers, who are to devote themselves to the 

 instruction of children — and in this case I believe there is something 

 to be said for it — it is quite opposed to von Helmholtz' view of 



