THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE, 



* fc R V *T 



[FIFTH SERIESJf f£B^° < r> 



FEBRUARY 1899. • : _,.^» 



.*'' * 



XL Radiation Phenomena in the Magnetic Field. — Magnetic 

 Perturbations of the Spectral Lines. By Thomas Preston, 

 M.A., D.Sc, F.R.S* 



If 



IN the April number of this Magazine f I described a 

 series of observations on u Radiation Phenomena in a *)j\ 

 strong Magnetic Field. 5 '' Briefly stated, the results obtained 

 showed that while the majority of spectral lines became 

 triplets when the source of light was placed in the magnetic 

 field and viewed across the lines of force, yet this did not 

 hold good of all lines, for some were observed to be resolved 

 into quartets, or sextets, or other forms by the magnetic 

 field under precisely the same circumstances. 



I pointed out at that time that these quartets &c. 

 might be regarded as modified forms of the normal or 

 standard triplet form, and might possibly be derived from it 

 by reversal. Thus, if each line of a triplet be reversed (that 

 is, if an absorption-band occurs along its middle), then we 

 have six lines instead of three, and so on for the other forms. 

 I also pointed out, however, that the general appearance of 

 these modified forms did not by any means favour that 

 explanation, for they possessed none of the ordinary cha- 

 racteristics of reversals. Nevertheless, this explanation could 



* Communicated by the Author. 



t Phil. Mag. vol. xlv. p. 325 (1898). The experiments described in this 

 paper were performed in Oct. and Nov. 1897, and communicated to the 

 Royal Dublin Society in December 1897. See Trans. Rov. Dubl. Soc. 

 vol. xv. p. 385 (1898). 



Phil Mag. S. 5. Vol. 47. No, 285. Feb. 1899. N 



