Experimental Researches on Gravitation. 503 



this really does happen. Hence I will put p s = 2*0, 

 -\|r 5 = 0*433, and from this we can deduce 



s> _'£« —J^iL— 4-97 

 vs ~<f s 0-433 



That is to say, it ensues that the suns true density is the 

 triple of what it is believed to he by the astronomers (1*41). 



But," although considering it possible to take as true the 

 general result about a true density greater than the apparent, 

 I do not attach exceeding importance to the determination I 

 have been working out. The problem on the research of 

 the true density so laid down, shows itself to be rather un- 

 certain. In fact, it is sufficient to admit even a relatively 

 slight error in the determination of e, to have the value of 

 8 VS notably altered. That can be deduced from the following- 

 table :— " 



e. 



h. 



fe 



0-0007 



4-80. 10~ 12 



2-42 



00009 



618. 10 -12 



3-27 



0-00098 



0-73. 10~ 12 



6*73 (experimental determination) 



o-oon 



7-55 . 10 -12 



10-04 



0-0012 



8-23. 10 " 12 







L e., it is enough to admit e = 0'0011, to have the true density 

 rise to 10*04. 



But, considering the yjr function, we come to note an 

 interesting consequence : the h constant cannot be greater 

 than 7*55 . 10 ~ 12 ; because if it were, in the sun's case the 

 following expression ought to be exact : 



^ >7-65.10" 12 , or p.^>0-75, 



and such a condition never can be verified from (5), which 

 for great values of p, gives at most py\r — f. 



In other words we can also say inasmuch as the sun lias an 

 apparent density equal to 1*41, the coefficient of absorption h 

 cannot be greater than 7*65 . 10~ 12 . The experiment gives 

 6* 73 . 10~ 12 ; therefore the facts agree up to now with the 

 proposed theory. 



I bring these considerations to a close, calling attention 

 to the fact that if we admit the hypothesis of gravitational 

 absorption, the calculation worked out for the sun with the 

 simplification of constant density cannot lead us to very 

 erroneous results. In fact, if: we substitute for this hypothesis 

 of constant density, another law of variable density, this 

 will be, as a matter of course, greater at the centre than at 



