Address bv Sir David Gill. -5 



It is not wise to attempt to define too closely the borderland 

 of profitable scientific activity, for one cannot forget that about 60 

 years ago the French Philosopher Comte, in his Cours de Pliilo- 

 Sophie Positive, quoted the chemical constitution of the Sun and 

 Stars as an example of the Unknowable, a statement the fallacy of 

 which was proved by the subsequent results of Spectrum Analysis. 



And \et the greatest of scientific men have at times forgotten 

 .the futility of Aristotelian methods and been drawn aside b} some 

 irresistible attraction from the strait and narrow paths of the Ba- 

 <:onian method. 



I mav perhaps be allowed to quote an interesting instance with- 

 in my own experience. 



Some 20 vears ago, in the old smoking-room of the Athenaeum, 

 I was talking with Professor Huxley about the rising scientific men 

 in England, when he brought up the name of my late dear friend 

 •George Romanes. " Now," said Huxley, " there is a man that I regard 

 as the ablest of the young men in my line of work; but of late he 

 has taken to philosophy, and it is all up with a man of Science when 

 he does that." Some years later George Romanes founded the 

 Romanes Lectureship at Oxford. The idea i)f the foundation was 

 to obtain every year from some distinguished man, towards the 

 ■close of his career, a lecture which should, as far as possible, repre- 

 sent the outcome of his experience and knowledge. At the end of 

 10 years the lectures were to be printed and published in a volume, 

 which might thus be expected to contain the best thoughts of the 

 -decade. Gladstone was the first Romanesdecturer, Huxley was tlie 

 .second. Not very long after the delivery of his lecture I again met 

 Huxley in the same place and reminded him of our earlier conver- 

 sation, asking how it was that, after censuring Romanes so severely 

 for dabbling in philosophy, his own Romanes lecture was only 

 philosophy of the dee^Dest dye. " Ah, yes," he replied wdth a smile, 

 ■*' I suppose it is the decadence of old age." 



Pure Mathematics is the only Science which, if its original postu- 

 lates and definitions are granted, is independent of comparison with 

 external nature, and it might ha^■e been developed from them alone 

 ito its present stage, or further, by generations of men who never saw 

 the earth or sky. Carping philosophers may gird at the sufiiciency 

 •of its axioms and definitions, but these axioms and definitions are 

 self-evident to common-sense, and no part of the superstructure 

 logically raised on them has ever departed a hair's breath from the 

 -truth under any stress to which, during the centuries since Pvthag- 

 ■oras. it has been exposed. 



A supreme point to be impressed on every worker in Science 

 is the cultivation of the most rigorous accuracv of thought, work 

 and expression. In the sciences of observation too much stress can- 

 not be laid upon the necessity of accepting for fact only that which 

 is really fact. This, on the face of it, seems a needless statement. 

 But in the determination of any fact w^hich depends on measure- 

 ment or estimation by human agency there must remain an outstand- 

 5ng uncertainty which may be great or small according to the skill 



