356 THE ADDRESSES, LECTURES, ETC., OF 



" 2. That the origin, of the luminous column is to be sought for 

 at its negative end ; that the luminosity is an expression of a 

 demand for negative electricity ; and that the dark spaces are 

 those regions where the negative terminal, whether metallic or 

 gaseous, is capable of exerting sufficient influence to prevent such 

 demand. 



" 3. That the time occupied by electricity of either name in 

 traversing a tube is greater than that occupied in traversing an 

 equal length of wire, but less than that occupied by molecular 

 streams (Crookes' radiations) in traversing the tubes. Also that, 

 especially in high vacua, the discharge from the negative terminal 

 exhibits a durational character not found at the positive. 



" 4. That the brilliancy of the light with so little heat may be 

 due in part to brevity in the duration of the discharge ; and that 

 for action so rapid as that of individual discharges, the mobility 

 of the medium may count as nothing ; and that for these infini- 

 tesimal periods of time gas may itself be as rigid and as brittle as 

 glass. 



" 5. That striae are not merely loci in which electrical is con- 

 verted into luminous energy, but are actual aggregations of 

 matter. 



" This last conclusion was based mainly upon experiments made 

 with an induction coil excited in a new way viz. directly by an 

 alternating machine, without the intervention of a commutator or 

 condenser. This mode of excitement promises to be one of great 

 importance in spectroscopic work, as well as in the study of the 

 discharge in a magnetic field, partly on account of the simplifica- 

 tion which it permits in the construction of induction coils, but 

 mainly on account of the very great increase of strength in the 

 secondary currents to which it gives rise." 



These investigations assume additional importance when we 

 view them in connection with solar I may even say stellar 

 physics, for evidence is augmenting in favour of the view that 

 interstellar space is not empty, but is filled with highly attenuated 

 matter of a nature such as may be put into our vacuum tubes. 

 Nor can the matter occupying stellar space be said any longer to 

 be beyond our reach for chemical and physical test. The spectro- 

 scope has already thrown a flood of light upon the chemical con- 

 stitution and physical condition of the sun, the stars, the comets, 



