478 BEI.L SYSTEM TECHNICAL JOURNAL 



tions arc truly due to waves issuing from the doublet and not to some 

 unhapin' peculiarit\' of the receiver — and the former alternative is 

 considered the more probable one — then there is good reason for 

 believing that the spectrum of artificial waves has been prolonged 

 to o\erlap the spectrum of natural waves, and the lacuna is closed.' 



Till-: DiscovKRY OF Isotopes 



Thirteen addilional elements having been analyzed into isotojxjs 

 by Aston, the moment is opportune for restating the two great series 

 of discoveries which have disclosed the hidden law and the underlying 

 unity of the chemical elements. Twenty-five years ago, the labors of 

 chemists had resulted in setting apart about seventy-five distinct, 

 unchangeable, non-interconvertible substances as "the elements"; 

 anrl the ancient ambition to describe all forms of matter as combina- 

 tions or modifications of a single, truly fundamental element must 

 have seemed to be definitely frustrated. It is true that there were 

 undeniable signs of a family relationship among the elements. They 

 could be classified into groups of elements more or less alike in their 

 ■properties; and when they were arranged in the order of their com- 

 bining weights, there was distinctly a periodic variation of chemical 



' Dr. Ernest Fox Nichols died suddenly on the twenty-ninth of April, 1924. .\ 

 few days earlier he had very graciously offered to inform nie of his latest work in 

 extending the spectrum of artificial waves, hitherto unpublished except in brief 

 reports before the Physical Society. He discussed the matter with his collaborator 

 Dr. Tear, and to present his final formulation of his great achievement I can do 

 no better than to quote verbatim a letter which Dr. Tear kindly wrote to me on 

 .Jipril 29th: 



"The most satisfactory data we have at present has been obtained with receivers 

 whose fundamental wavelengths are long compared with those to be measured. 

 The electrodes of our smallest oscillators are 0.1 mm. in diameter and 0.1 mm. long. 

 The glass seal covers approximately one-half their length. The fundamental wave- 

 length of such an oscillator is of the order of 1 mm. The distribution of the dielectric 

 and the means of excitation are such however as to accent certain harmonics and to 

 suppress the fundamental and other frequencies. The interference curves show 

 then the presence of one high frequency, usually the second or fourth harmonic, 

 plus the low frequency of the receiver. The interference persists for three or four 

 cycles and is reproducible, although the construction of such minute seals intro- 

 duces the element of chance, frequently making it necessary to construct several 

 oscillators before finding one having the right proimrtions of bare and glass-covered 

 electrode-surface to bring out one fre(|uuncy and suppress the remaimler. 



"It is in a way jierplexing that although chance proportions of glass and metal 

 bring out one harmonic to a greater or less degree, the fundamentals of these smallest 

 oscillators do not show up at all. It is of interest, too, to note that a sheet of glass 

 0.2 mm. thick, such as the seals are made of, transmits but 2.S' ^ of the 0..?2 mm.- 

 radiation from the mercury arc. We have been led to the inUrprelation lh.it the 

 particular standing wa%es which can exist upon these sin, Ml oscill.itnrs .ire ileler- 

 mined by the l<Kation of the glass-oil boundary-surface, and ih.it the predomin.int 

 wavelength is the fundamental wavelength of that part of the oscillator which is 

 in oil between the two glass-oil surfaces. The wtwelenglhs which we have isolated in 

 this way extend to the 0.22 mm. limit which we reported at Boston." (That is, at 

 the Boston meeting of the Physical Society, December, 1922. Italics mine. — 

 K. K. D.) 



