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mineral elements. Professor Ramsay is dealing with vagrant atoms of 

 an astral nature. During the course of the present year he has announced 

 the existence of no fewer than three new gases— krypton, neon, and 

 metargon. Whether these gases, chiefly known by their spectra, 

 are true unalterable elements, or whether they are compounded of other 

 known or unknown bodies, has yet to be proved. Fellow workers 

 freely pay tribute to the painstaking zeal with which Professor Eamsay 

 has conducted a difficult research, and to the philosophic subtlety brought 

 to bear on his investigations. But, like most discoverers, he has not 

 escaped the flail of severe criticism. 



There is still another claimant for celestial honours. Professor Nasini 

 tells us he has discovered, in some volcanic gases at Pozzuoli, that liypo- 

 thetical element Coronium, supposed to cause the bright line 531 GO in 

 the spectrum of the sun's corona. Analogy points to its being lighter and 

 more diffusible than hydrogen, and a study of its properties cannot fail to 

 yield striking results. Still awaiting discovery by the fortunate specti'o- 

 scopist are the unknown celestial elements Aurorium, with a characteristic 

 line at 5570-7 — and Nebulum, having two bright lines at 500705 and 

 4959-02. 



The fundamental discovery by Hertz, of the electro-magnetic waves 

 predicted more than thirty years ago by Clerk Maxwell, seems likely to 

 develop in the direction of a practical application which excites keen 

 interest — I mean, the application to electric signalling aci'oss moderate 

 distances without connecting wires. The feasibility of this method of 

 signalling has been demonstrated by several experimenters at more than 

 one meeting of the British Association, though most elaborately and with 

 many optical refinements by Oliver Lodge at the Oxford meeting in 1894. 

 But not until Signor Marconi induced the British Post-Otfice and 

 Foreign Governments to try large scale experiments did wireless signalling 

 become generally and popularly known or practically developed as a 

 special kind of telegraphy. Its feasibility depends on the discovery of a 

 singulai'ly sensitive detector for Hertz Avaves — a detector whose sensitive- 

 ness in some cases seems almost to compare with that of the eye itself. 

 The fact noticed by Oliver Lodge in 1889, that an infinitesimal metallic 

 gap subjected to an electric jerk became conducting, so as to complete an 

 electric circuit, was rediscovered soon afterwards in a more tangible and 

 definite form and applied to the detection of Hertz waves by M. E. 

 Branly. Oliver Lodge then continued the work, and produced the 

 vacuum fil'mg-tuhe coherers with automatic tapper-back, which are of 

 acknowledged practical service. It is this varying continuity of contact 

 under the influence of extremely feeble electric stimulus alternating with 

 mechanical tremor, which, in combination with the mode of producing 

 the waves revealed by Hertz, constitutes the essential and fundamental 

 feature of 'wireless telegraphy.' There is a curious and widely spread 

 misapprehension about coherers, to the effect that to make a coherer work 



