598 DRJ. HALM ON STRUCTURE OF THE SERIES OF LINE- AND BAND-SPECTRA. 4 
In my demonstration of the superiority of the RypBERG-THIELE equation over that 
of Kayser and Runes I| hope that I may not have conveyed the impression that I 
was insensible of the undoubtedly great merits of the latter. Hveryone who has 
studied the problem here discussed cannot but recognise how much we are indebted to 
Professor Kaysrr and his co-workers for the enormous advance of our knowledge in 
this field of spectroscopic research, an advance which without his empirical formula 
would not have been possible. Our feeling of admiration and gratitude for this great 
physicist’s work in a novel and difficult sphere of optics, to which he has so long and 
successfully devoted his high scientific abilities, will doubtless stand unabated even if 
his formula should not be finally accepted as the mathematical expression of the law of 
those marvellous spectral regularities, the knowledge of which we owe chiefly to his 
ingenious investigations. 
