1895.] 



President's Address. 



123 



to which Mr. Lockyer many years ago gave the name of "helium." 

 The spectrum of this terrestrial gas was seen at first as an extremely 

 narrow and sharp line of a brilliant yellow colour, close to, and 

 slightly more refrangible than the sodium lines, Di and D 2 , and 

 having a wave-length near to 5876, this, according to recent de- 

 terminations, being the wave-length of the solar line of helium, or, 

 as it is usually designated, D 3 . Shortly after its discovery, Professor 

 Runge, of Hanover, announced that the yellow line of Ramsay's gas 

 was double, consisting of a strong component having a wave-length 

 of 5875'88, and a faint component having a wave-length of 5876'21. 

 As no observer had seen the solar line D 3 double, doubt was thrown 

 on the first assumption that Professor Ramsay had actually isolated 

 a solar element hitherto unknown on the earth. A few weeks 

 later, however, Dr. Huggins, in England, and Professor Hale, in 

 America, have detected the presence of a faint luminous companion 

 of D 3 in the spectrum of the chromosphere, and as these solar lines 

 have the same wave-lengths as those of the corresponding terrestrial 

 lines, the doubts at first raised have been set at rest. The body 

 giving rise to the solar line D 3 , and Professor Ramsay's new gas from 

 cleveite, uraninite, broggerite, monazite, and many other rare 

 minerals, is now admitted by chemists, physicists, and astronomers 

 to be the same substance — helium. 



The conferring of the Davy Medal on Professor Ramsay is a crown- 

 iDg act of recognition of his work on argon and helium, which has 

 already been recognised as worthy of honour by scientific societies in 

 other countries. For his discoveries on these gases he has already 

 been awarded the Foreign Membership of the Societe Philosophique 

 de Geneve, and of the Leyden Philosophical Society. He has had 

 the Barnard Medal of the Columbia College awarded to him by the 

 American Academy of Sciences, and within the last few weeks he 

 has been elected a Foreign Correspondent of the French Academie 

 des Sciences. 



Five years have now passed since you elected me to be your 

 President. Living at a distance of 400 miles from London, I felt 

 that it could not be possible for me to accept the honour when the 

 possibility of its being offered to me was first suggested. I accepted, 

 with much misgiving as to my ability to perform the duty which 

 would fall upon me ; and now, after having been re-elected four 

 times, I feel that if the interests of the Society have not suffered 

 under my presidency, it is chiefly because they have been so 

 faithfully and unintermittently cared for and worked for by the other 

 officers, the Treasurer and the Secretaries, who have left nothing 

 undone that could be done to promote the welfare of the Royal 

 Society. For their unfailing kindness to myself I can only offer my 



4 



