200 



NATURE 



{June 26, 1879 



Pressure 6'6 mm., 8,684 M, with 8,040 cells. 12 lumin- 

 osities very similar to those shown at Fig. 5 in the Plate, 

 the last adhering to the positive. The C line not visible 

 in a nebulosity with the spectroscope, but that and the 

 F line were both to be seen in the glow around the 

 negative. 



Pressure 5*9 mm., 7,763 M, 8,040 cells, C. 0-02056 W.^ 

 13 luminosities like those Fig. 6 in the Plate. With 100,000 

 ohms, C. o'oi39o W, there were 10 luminosities not so 

 wide as those when there was no resistance. 



Pressure 6'i mm., 8,026 M, 8,040 cells, C. o'oi9io W- 

 At first 13 luminosities a little unsteady, then ii| per- 



FlG. 12. 



fectly steady, like Fig. 6 in the Plate. F and C visible 

 in the glow around negative. F was not visible in a 

 luminosity. 



Pressure 4-4mm., 5,789 M, 8,040 cells. 12 luminosities 

 as depicted in Fig. 6 in the Plate, which is copied from a 

 photograph 2 obtained in 4 seconds. 



Pressure 4-0 mm., 5,263 M, 8,040 cells. 15 luminosities 

 as shown in Fig. 7 in the Plate, from a photogi-aph taken 

 in 4 seconds. 



Pressure 3-6 mm., 4,737 M, 8,040 cells, 30,000 ohms 

 resistance. 15 luminosities almost touching, like Fig. 7 

 in the Plate. 



Pressure 3 mm., 3,947 M, 4,800 cells, C. 0-0362 W, the 

 resistance of the tube being 88,600 ohms. There were 24 

 steady blue strata and a space of about 6 inches con- 



FlG. 13. 



fused towards the positive ; with 200,000 ohms resistance 

 in the circuit the strata became pink, the current being 

 0-01469 W. 



Pressure i mm., 1,316 M, 3,600 cells, C. 0-03896 W, the 

 resistance of the tube being 59,170 ohms. The tube was 

 filled to within one inch of the negative with strata all 

 blue, but they turned pink and tongue-shaped when 

 200,000 ohms resistance was introduced, which reduced 

 the observed current to 0-00782 W. The C and F lines 

 visible in the luminosities. When 7,590,000 ohms resist- 



ance was introduced, a very close and somewhat agitated 

 pink stratification was produced, like the left of Fig. 13. 



Some gas let in, pressure 3 mm., 3,947 M, 3,6oo cells 

 gave a current of 0-04901 W ; the resistance of the tube 

 was ascertained by substituting 47,000 ohms wire resist- 

 ance, which produced the same deflection. The strata 

 were blue, like those of 55 and 56, Fig. 14. For about 

 10 inches from the negative they took up an axial back- 

 wards and forwards steady rotation of about a quarter 

 turn. 



With 174,000 ohms resistance, making with the battery 

 and tube a total of 261,000, the current measured was 

 0-00879 W. The strata turned pink and assumed the 

 tongue-form. Fig. 15 ; with 783,000 ohms in circuit very 

 close strata. In the rotating mirror a flow towards the 

 positive was observed until a break occurred in the strati- 

 fication ; the flow was then irregular and backwards and 

 forwards. 



Pressure 1-7 mm., 2,237 M. The current of 2,400 cells 

 passed ; with 3,600 cells the current was 0-03858 W, pro- 

 ducing perfectly steady strata, of which a photograph was 

 obtained in four seconds ; a facsimile of it is given. Fig. 8 

 in the Plate. The strata were blue, but on introducing 

 500,000 resistance the current was reduced to 0-00175 W, 

 and the strata turned pink and assumed the form Fig. 9 in 

 the Plate, which is a facsimile of a photograph obtained 

 in 19 seconds. 



Pressure 0-8 mm., 1,052 M, 3,6oo cells (C.) 0-19940 W. A 

 spiral series of tongues depicted in Fig. 10 in the Plate, from 

 a photograph which, however, could scarcely be exposed 

 long enough in consequence of the screw-like motion of 

 the tongues. This motion appeared to be from positive 

 to negative.' On introducing 900,000 ohms resistance, 

 (C.) 0-003414 W, the tongues grouped themselves in pairs, 

 of which there were 40, and changed from blue to pink. 

 Examined with the spectroscope, the line C had disap- 

 peared. The tube was connected with the condenser of 

 42-8 microfarads and 3,240 cells, a resistance of 200,000 

 ohms being in circuit (C.) 0-007461 W. At the full potential 

 the same spiral series of blue tongues, quite steady, was 

 produced, and these made a complete rotation in 2>'^ 

 seconds. On breaking connection between the battery 

 and condenser, the strata gradually changed to pink as 

 the charge of the condenser ran down through the tube. 



Tubf 129, 6th Charge of Hydrogen. — The tube, at 0-9 mm., 

 1,184 M, was partially charged with hydrogen by letting in 

 4 small calibrated charges, which increased the pressure 

 each time 1-4 mm., pressure 6-5 mm., 8,684 M, the resist- 

 ance of the tube was found to be 170,000 ohms, and the 

 total resistance of the whole, 8,040 cells, 130,000 ohms, or 

 an average of 16-6 per cell. With 6,960 cells the current, 

 through the tube alone, was 0-02456 W, and there were 

 produced 9 luminous entities as shown in Fig. 5 in the? 

 Plate, taken from a photograph obtained in lA second. 



The gas in the tube at the same pressure, namely,! 



6'5 mm., 8,040 cells, C. 0-02634 W- There were 7 entities 

 as depicted in Fig. 4 in the Plate, copied from a photo- 

 graph obtained in one second. 



Pressure 6-5 mm., on the introductipn of 300,000 ohms 

 resistance with 8,040 cells, C. 0-0138W, making a total 

 resistance, inclusive of the tube and the battery, of 



' C denotes currents ; WT webers. 



^ Varley.C. F. {Proc. Roy. See, xix., 1E71, pp. 238-239) succeeded in 

 photographing by an exposure of thirty minutes an arck discharge in a 

 vacuum tube, so faint that in a perfectly dark room he was " sometimes 

 unaware whether the clu-rent was passing or not." 



600,000 ohms, two luminosities were produced as seen in 

 Fig. 2 in the Plate, taken from a photograph obtained in 

 2 seconds, which, however, had to be corrected from a 

 drawing, as there was a slight movement in the lumi- 

 nosities. 



Pressure 3-6 mm., 4,737 M, 4,800 cells. Strata re- 

 sembling Fig. 16, but near the negative the strata were 



> De la Rive (Geneve M/m, Soc. Phys. xvii., 1863, p. 72) describing the 

 appearance of a nitrogen tube, says ; ' ' Ces stries semblent former une h^Iice 

 anlmi^e d'un mouvement de rotation autour de son a.xe. ' 



