472 TBANSACTIONS OF SECTION A. 



opened out a large new field of investigation into the invisible rays of long 

 wave-length proceeding from heated bodies. He analysed in minute detail the lunar 

 heat spectrum, and, more recently, he conducted an inquiry into the nature of 

 the radiations emitted by the glow-worm. In 1881 he conducted his researches 

 into the solar heat of the earth's atmosphere. In 1887 he became Secretary to 

 the Smithsonian Institution. The result of twenty years' labour is to be found 

 in the accurate determination, by temperature alone, of over seven hundred lines 

 in the invisible red spectrum, lines which are fixed with an average probable 

 error of about one second of arc. In 1891 he published his experiments in 

 aero-dynamics, in 1893 'The Internal Work of the Wind,' and in 1896 he 

 demonstrated by actual experiment that a body nearly a thousand times heavier 

 than air can be driven through and sustained by it. His published works show 

 great literary charm. He especially excelled in the presentation of abstruse 

 subjects in simple and non-technical language. This is, perhaps, hardlj' the 

 occasion to refer to his social qualities. Those who had the privilege of his 

 acquaintance, however, can best testify to his quickness of insight, his intense 

 sympathy, especially with the young, and the impression of capability which he 

 produced upon all with whom he came in contact. 



The tragic death of Professor Curie was felt as a calamity, not only by those 

 closely interested in the march of scientific discovery, but also by those who had 

 but a superficial knowledge of his work. A teacher for more than twenty years, he 

 was nevertheless enabled by his enthusiasm and energy to perform those researches 

 which will ever be connected with his name and that of his wife. So eutirelj' has 

 public attention been attracted to their joint work on the separation of the com- 

 pounds of radium and their properties that we are apt to overlook other great 

 services he rendered to science. His paper on 'The Effect of Temperature on the 

 Magnetic Properties of Bodies ' led to the discovery of the law that for feebly 

 magnetic substances the coefficient of magnetism varies inversely as the absolute 

 temperature. He also pointed out that the magnetisation of diamagnetic sub- 

 stances appeared to be independent of the temperature and physical state, indicating 

 diamagnetism as an atomic property. 



It is pleasing to reflect that the importance of his discoveries received 

 immediate recognition. It was but three years before his death that he announced 

 to the French Academy the discovery of the new element, and in the same year he 

 and Mme. Curie received the Davy Medal of the Royal Society and the Nobel 

 Prize ; and in July of last year he was elected to the French Academie des 

 Sciences. He was one of the most modest and retiring of men, and this honour 

 came to him unsought ; his name will ever be remembered as one of the most 

 notable of that brilliant band of workers who have within recent years so greatly 

 extended the domain of physics by the discovery of radio-activity. 



A quarter of a century has passed since this Section, meeting in this city of 

 York, had the privilege of listening to a Presidential address by the pioneer of 

 natural knowledge whom we now know as Lord Kelvin, and it may possibly bo a 

 not unprofitable task to review briefly a few of the advances which must render 

 the interval a memorable one in the annals of science. 



Lord Kelvin summarised the stores of energy from which mechanical effects can 

 be drawn by man as follows : — 



(1) The food of animals. 



(2) Natural heat. 



(3) Solid matter found in elevated positions. 



(4) The natural motions of water and air. 



(5) Natural combustibles. 

 (G) Artificial combustibles. 



ITie twenty-five years which have since elapsed have not made it possible to 

 extend this list. It is true that within the last few years the discoveries connected 

 with radio-activity have enormously increased our estimate of the stores of energy 

 suirounding us, but so far these additional stores cannot be regarded by vis 9s 



