( 589 ) 
sun-spot spectra; as a general rule we may expect that the separation 
of lines in spot spectra becomes more distinct and of larger amount 
by the use of analysers. 
The introduction of a Nicol in the beam may also reveal lines 
invisible without analyser. 
Several peculiarities observed in the distribution of intensity in 
spot lines, remind one of the now specified superposition pheno¬ 
mena 1 ); cf. § J9 below. 
8. Superposition effects of nearly, though not exactly, the same 
nature occur if lines with the same direction of vibration are superposed 
and if the continuous source of light emits unpolarised light. In the 
more complicated divisions the now specified superposition occurs also. 
It is just possible that the superposition of the outer components of 
the sextet, type D„ produces only dark, that of the inner and the 
next outer components, black lines in the continuous spectrum. 
It is easily seen that also in the case of the quartet, type D lt 
black lines may be produced. The darkest parts may be seen some¬ 
what nearer to the middle of the complete figure, than the outer 
components of the quartet. 
It seems unnecessary to illustrate this by figures. Examples of the 
specified actions will be given presently. 
9. Our observations and spectrograms relate besides to the two 
principal directions (parallel and at right angles to the lines of force), 
also to directions inclined to the field. 
In the present, first, communication, observations are discussed, 
relating to 5 different angles between the field and the direction of 
propagation of the beam (Voigt’s <f, Lorentz’s #). 
These values are : 90°, 0°, 60°, 45°, 36°-39°. 
The results of the work relating to these angles have been recorded 
on nearly 100 spectograms. 
10 . Observations perpendicular to the field. 
In the upper of the three stripes which are present in the field of 
view (see § 5), the light vibrates vertically; in the lowest one hori¬ 
zontally, whereas the middle part relates to natural light. 
Under the influence of the magnetic field we therefore see the 
vertically vibrating components as narrow black lines. The quartet 
of the D l line, the sextet of the line, may be seen very clearly 
9 A figure equivalent to the one now given concerning the influence of super¬ 
position of magnetically divided components was already drawn for emission lines 
in Zeeman. Doublets and Triplets in the Spectrum produced by external magnetic 
forces. Phil. Mag. July 1897 § 7. 
