496 Prof. Q. Majorana : Theoretical and 



the eventual variation of weight for a mass m, relatively 

 small, surrounded by another mass M much bigger. In 

 fact, as it is probable, according to the already made hypo- 

 thesis, that the flux of the mass m must be partly absorbed 

 by M, so also the gravitational flux that is put forth by the 

 earth must weaken itself, before it reaches ??i, across M. 

 I suppose this mass M shaped as a sphere, with radius r ; 

 and the mass m small, and situated at M's centre. It* & is 

 the density of the substance that forms M, we shall have, 

 according to (1) and (2), 



this represents the flux of the mass m that succeeds in 

 emerging from M. Taking in correspondence m a and m v as 

 the true and apparent mass of m, w T e have 



m a _ A5r -Mr 



- —e , or m a =.m v e ; 

 m 



r being very small (at the most a few decimetres), we have 



m a = m v {l — JiBr), 



This means that the mass m would undergo a variation (of: 

 diminution) of 



e = m v li8r (9) 



From this the value of h could be deduced 



fc=-4-. ...... (io) 



m v or 



We can establish what would be the order of magnitude 

 of e, in a possible experiment of this kind. Let us put 



m=m p =lkg.; 8 = 13*60; r=10cm. 



This corresponds to the conditions that I realized in an 

 experiment that I shall describe : I had taken for m a leaden 

 ball; mass Mwas mercury, symmetrically distributed aroundm. 

 Since h is probably equal to about 10~ 12 (on the hypothesis 

 that the true density of the sun is a little greater than 2), 



e = 1000 gr. . IO" 12 . 13*60 .'10 cm. =.1'4 . 10" 7 gr. 



This means that it would be necessary to be able to detect 

 a variation of 1/10,000 of a mg. in 1 kg. The apparatus 

 employed to carry out the planned experiment ought to fulfil 

 such condition. 



Description of the experimental disposition. — A Huprecht 

 balance of the bearing of about 1 kilogram was removed 

 from its original protecting box and enclosed in a metallic 

 box shaped like a T (tig. 3), able to resist the atmospherical 



