130 The Ottawa Naturalist. [October 



burgh, Mr. Balfour has worthily sustained the distinction of his 

 family name. His masterly treatises *' Philosophic Doubt," " The 

 Foundations of Belief," and other works, have given him eminence 

 as a speculative philosopher. The late Principal John Caird, of 

 Glasgow, once said, in my hearing, " It is easy to be a great philo- 

 sopher in the company of scientists, and easy to be a great scientific 

 man amongst philosophers ; but Mr. Balfour is a great philosopher 

 among philosophers, and a scientist among scientists." Of Mr. 

 Balfour's real interest in science I have personal knowledge, and I 

 well remember when I had the honor of first meeting him, that I 

 was startled by his familiarity with a line of special zoological 

 research in which I was at the time engaged, fifteen or sixteen 

 years ago. 



Cambridge which boasted a Mewton, a Couch-Adams, and a 

 Darwin in the past, and can claim to-day a Kelvin, and a Rayleigh 

 and other leading scientists, was privileged to listen to a profound 

 and closely-reasoned address on the Aim and Basis of Scientific 

 Investigation from the President of the British Association, the 

 membership of which Association this year exceeds 2,500. 



The precise title chosen by Mr. Balfour was " Reflections 

 suggested by the New Theory of Matter," and after pointing out 

 that physical reality, not mere appearances or changing pheno- 

 mena, formed the object of the highest scientific research, the 

 President rapidly reviewed the ideas about matter which have 

 prevailed since Newton's epoch-making " Principia " (published in 

 1687). 



Old Conception of Matter. 



In the 17th century the average scientist regarded the uni- 

 verse as composed of ponderable matter, various in kind, per- 

 manent and indestructible : but capable of transformation by heat, 

 chemical affinity, &c. Interstellar space in the vast heavens was 

 conceived to be occupied by a thin, continuous kind of matter 

 called ether, whose undulatory motions resulted in light, radiant 

 heat, and electricity. Young's wave theory of light, a hundred 

 years ago, led to the abandonment of such theories as Newton's 

 light corpuscles or the emission by luminous bodies of material 

 nolecules which produced the sensation of light in the brain. 



