1272 
the same way, the movement and radiation of molecules can be 
described. Thus knowing the effect of the radiation from the mole- 
cules when a periodical radiation strikes them, we can from this cal- 
culate for each case the influence of a crystal on RÖNrceN rays. I 
will therefore consider the problem of a radiation of the wavelength 
2 striking the crystal. Under the influence of this radiation the 
molecules will emit spherical waves. I will indicate the vector of 
radiation for the radiation emitted by a molecule situated at the 
A t r 
— cos 2x (+ -~ 2) ie pe ER 
r de ae 
this formula representing the vector of radiation in the point & 1 ie 
while A depends on the direction. The radiation of a point (1) 
in the point §7$ is now represented by 
A t o k‚a 
pn Gar is ): 
S 
origin, by 
where @ denotes the distance of $76 from (1). This distance is 
given by 
or EE tek, HEE) + HED +o (Chiate) B: 
Substituting in the amplitudo @ by r (which is allowed since h,a 
is small compared with 7 ete.) then we get for the vector of light 
considered 
A t 5 
DER ee k,— =k, zel | 
r dr À À r 
5 AN Fet (Ok +k, +24) 
And in ae to find the total vector of radiation we have to 
sum up the expression (3) over all molecules struck (or rather put 
into vibration) by the primary radiation. In doing so we obtain 
the formula given by Laur and with that, his cones of maximal 
intensity. 
However, we can show that there are other maxima still, besides 
the cones of Laur. I will suppose 7 to be so great that we can 
neglect the fourth term. 
The maxima that do not appear in Lavg’s theory can be made 
to appear by first taking into account the interference of the points 
for which 
k, (1-2 )—%, eS es 
7 7 1 
(3) 
