( 737 ; 



opposite ; an asymmelrv in (he break of the bands towards both 

 sides — with respect to their position with field off — appeared 

 to exist, but could not be measured with sufficient certainty. At a 

 temperature considerably exceeding that of liquid air, the blue bands 

 are no longer to be determined in the grating spectrum. 



§ 16. B. Fair of hands in the red; we call them R^ and E^. 



1) At —193° we have /^, =691,7 and /^, = 693,1, the distance 

 measured in the grating spectrum being 1,38 ft fi. 



Line R, -. Width with field off 0,065 nn. With 23 kgs. a triplet 

 begins to appear, which is not yet clearly visible with 18 kilogauss ; 

 lefthand line (red side) not sharply divided from middle line, forming 

 together a strong line, 0,10 ftjt wide; righthand line (violet side) 

 divided from middle line at a distance of 0,09 mi. With 26,5 kgs. 

 the triplet further resolves, the distance on either side becoming 0,11 ji/ti. 



With 36 kgs. the lefthand line is strong, the middle line perhaps 

 stronger still, not sharply divided, distance 0,165 jn/i; the righthand 

 line faint, at a distance of 0,14 mi from the middle line. 



Line R,: Width with field off 0,055 (uji. With 23 kgs. triplet: 

 lefthand line not separated from middle line, forming together broad 

 line 0,075 f/ft wide; righthand line separated from middle line at a 

 distance of 0,07 mi- With 26 kgs. the triplet further resolves ; 

 distance 0,08 and 0,09 im respectively. 



With 36 kgs. the lefthand line is rather strong, not quite detached 

 from the middle line, at a distance of 0,115 ft^u; the righthand line 

 faint, more clearly separated from the middle line, at a distance 

 of 0,15 fxft. 



In all these cases the lateral components were circularly polarised 

 in the opposite sense ; as the middle line vanished at neither of the 

 two positions of the 'j ^ plate, it could not be circularly polarized ; 

 linear polarisation was not observed and quite excluded on account 

 of axial field-symmetry. It is not yet the moment here to enter into 

 an explanation of this highly remarkable phenomenon ; it may per- 

 haps simply be due to imperfect resolution of the inner lines of a 

 (juadruplet '). A magnetic displacement of the middle line with respect 

 to its position with field off") could not be ascertained; at all events 

 it never amounted to more than 1 or 2 hundredths of mi. 



There is no reason in this case to doubt of the proportionality of 

 the resolution with the intensity of the field. 



1) Gf. P. Zeeman, These Proc. Febr. 1908. 



-) Gf, H. Kayser, Handb. d. Spectroscopie, 2 p. 655, b^ig. 52. Something similar 

 was also sometimes observed tor the sextuplet of Do. 



50 

 Proceedings Royal Acad. Amsterdam. Vol. X. 



