KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 60. N:0 8. 75 



I II 



4 = -15° A =-44° 



£= + 61° D = -18° 



V = -517 km./ sec . F = - 813 Wsec. 



Z = + 587kni. # = 0. 



Regarding the interpretation of the constant K we want to call attention to 

 the circumstance that it corresponds to a displacement of the spectral lines in the 

 same direction as that demanded by the general theory of relativity of Einstein. 

 This displacement is of the amount 



0,634 JiV 3km -/ sec ., 



where M designs the mäss of the celestial body emitting the spectre and p its 

 density. 



It might be uncertain if it is jnstified to use this formula with regard to the 

 spirals, as their spectrum ought probably to be considered as a resultant of indi- 

 vidual spectra of a great number of stars. If we accept nevertheless the validity 

 of the formula, we obtain, putting p = 10 -19 , and if K = 581 km. is assumed as 

 corresponding exclusively to an Einsteinian gravitation-effect: 



ilf = : 9-10 13 O. 



This result shows that the observed displacement exceeds by at least 1000 

 times the value one might expect by assuming a value of M aggreeing with our 

 present knowledge of the spirals. The Einsteinian theory however permits an ex- 

 planation of this displacement by taking into consideration the total field of gravita- 

 tion acting upon the light throughout its way to the Earth. 



§ 3. 

 Calculations of the proper motions of a number of the larger spirals, based on 

 all existing meridian observations and micrometrical measures, give somewhat smaller 

 values of the mean proper motion than those used in Section III. Probably the 

 proper motions derived from visual measurements as well as those obtained from 

 photographic determinations are illusory and indicate only the accuracy of measure- 

 ment of the method employed. Thus Curtis finds in his investigation mentioned 

 above 46 : 



Class of objects Mean proper motion 



Large diffuse nebulse 0",o36 



Planetary and gaseous nebulse . . ,028 



Very small nebulse (spirals?). . . ,040 



Spirals ,033. 



Nor do the proper motions of small nebulse (spirals?) calculated by Wirtz 

 seem to depend on the magnitudes or diameters of the spirals, which indicates that 



