1186 
respect to the central distance a of the two atoms of the molecule, 
which are supposed to be equal for the sake of simplicity. 
If consecutively the molecule axis is given all possible directions 
by the molecule being turned round one of the two atoms A,, the 
phase difference with which the secondary waves of A, and A, 
interfere in the point P changes. hence the intensity of the radia- 
tion there. , 
We calculate the mean intensity in the point P and inquire: am 
what way does this mean intensity vary with the situation of P on 
the plate b? 
For reasons of symmetry the mean intensity is of course the 
same for all those points ? for which the direction molecule — 
point P forms the same angle y with the direction of incidence of 
the Röntgen rays. With increase of gy the mean density however 
changes oscillatorily namely as: 
sin 220 
Pe En dk: ie aE 
92 
2210 
AG ey sl 
= SUN — . . . . 
9 
¢ - (2) 
[2 is the wavelength of the Röntgen rays; @ the distance of the two 
atoms (supposed as points *)) from each other}. 
The consecutive maxima and minima of (1) are in the following 
ratio to each other’): 
Fe OTS del OE el OF 
and lie at: 
2n0o=—=0; 4,49; 7,72; 10,90; 14,07. 
Iz || oo | 90° | — | — 
Pe HE 06 ra 1 AHA ane 
1) See appendix. 
2) It is convenient to confine ourselves for the present to this schematisation, 
till experiment shall give an indication for possibly necessary refinement of the 
scheme. _ 
sin X 
— in Jaunve u. Empe. Functionentafeln. 
X 
35) Comp. the tables for 
