192 On the JEther Molecules in Electric Conductors. 



1 millim. (on which the electrostatic measure is founded) is pre- 

 supposed, and in (II.), on the contrary, the acceleration in a 

 free fall (which forms the basis of the calculation with the usual 

 weights). 



If the conductor has a cross section of the unit of surface, 



a 



- is simply the density of the fluid reckoned in ordinary weights. 



Let it be put equal to D. Then would 

 _ <vr 



^ M = 9811. CD " •■••••• ( IIL ) 



Now this relation would attain a very much further-reaching 

 practical signification if, ■ in connexion with hypotheses which, 

 especially recently, have been repeatedly mooted, by M were to 

 be understood the number of aether molecules contained in a cubic 

 millimetre of the conductor, and by C the velocity of propagation 

 of light in the free aether. Then would D be at all events 

 much greater than the density of the aether in free space. Sir 



W. Thomson* has calculated that the latter is greater than y^ ; 



Belli f, indeed, has subsequently stated it to be at least ^ — — j^. 



As, unfortunately, I have not been able to examine Bellas calcu- 

 lation, while the value given by Thomson is certainly very much 



too small, yTTTs ma Y P erna P s De taken, as lying between the two. 



We should then have, understanding by M and C the above- 

 stated quantities, the inequality 



^ M< 9811.3.10" ° r< -l47-' ' ' (IV ' } 



and the inequality hereby expressed would indeed be consi- 

 derable. 



Now R is known for a definite conductor ; and so a maximum 

 value of M is given by the preceding relation, in case e is known 

 — or, conversely, a minimum value of e for a known M. It is 

 true, indeed, that both M and e are unknown to us ; but we have 

 more closely approximate ideas concerning e than concerning 

 M, and can therefore make use of the relation we have obtained 

 in order to gain similar notions with respect to M. 



If, e. g., for mercury we assume £=10 20 nearly, remembering 

 that, on the hypothesis of the equality of the velocity of elec- 



* Phil. Mag. S. 4. vol. ix. p. 36. 



t Cf. Fortschritte der Physik, 1859. 



