146 SOME OF THE LATEST ACHIEVEMENTS OF SCIENCE. 



stitueiit. has ])oen examined b}' many observers in all countries. The 

 phononionon has been subjected to phototrraphy with conspicuously 

 successful results by Prof. T. Preston in Dublin and by Professor 

 Michelson and Dr. Ames and others in America. 



It appears that the different lines in the spectrum are differently 

 affected, some of them being tripled with different grades of relative 

 intensity, some doubled, some quadrupled, some sextupled, and some 

 left unchanoed. Even the two components of the D lines are not 

 similarly inffuenced. Moreover, whereas the polarization is usually 

 such as to indicate that motions of a negative ion or electron consti- 

 tute the so.urce of light, a few lines are stated l)y the observers at 

 Baltimore, who used what they call the ''small" grating of 5 inches 

 width i-ul(>d with 65,000 lines, to be polarized in the reverse way. 



Further prosecution of these researches nuist lead to deeper insight 

 into molecular processes and the mode in which they affect the ether; 

 indeed, already valuable theoretic views have been promulgated by 

 H. A. Lorenz, J. Larmor, and G. F. Fizgerald, on the liiu^s of the 

 radiation theory of Dr. flohnstone Stonev, and the coiuiection of the 

 new phenomena with the old magnetic rotation of Fai'aday is under 

 discussion. It is inter(\'^ting to note that Faraday and a numlx'r of 

 more recent experinuMiters were led by theoretical considerations to 

 look for some such effect; and. though the inadequate means at their 

 dis})osal did not lead to success. ne\ertheless a first dim glimpse of 

 the phenomenon was obtained by M. Fievez, of the Royal Observatory^ 

 at Brussels, in 1885. 



It would be improper to pass without at least brief mention the 

 remarka])le series of theoretic papers by Dr. J. Larmor, pul)lished by 

 the Royal Society, on the relationship between ether and matter. By 

 the time these researches l)ecome generally int<dligible they may be 

 found to constitute a considerable step toward the further mathemat- 

 ical analysis and interpretation of the physical universe on the lines 

 initiated ])y Newton. 



In the mechanical construction of Rontgen'-ray tubes 1 can record a 

 few advances, the most successful being the adoption of Prof. Silvanus 

 P. Thompson's suggestion of using for the anticathode a metal of 

 high atomic weight. Osmium and iridium have been used with 

 advantage, and osmium anticathode tubes are now a regular article of 

 manufacture. As long ago as June, 1896, X-ray tubes with metallic 

 uranium anticathodes were made in my own laboratory, and were 

 found to work better than those with platinum. The difficulty of pro- 

 curing metallic uranium prevented these experiments from being con- 

 tinued. Thorium anticathodes have also been tried. 



Rontgen has drawn fresh attention to a fact very earh" observed by 

 English experimenters — that of the nonhomogeneity of the rays and 

 the dependence of their penetrating power on the degree of vacuum; 



