Strain along' the Lines of Force. 691 



The equation for elasticity introduced into Maxwell's 

 formula gives the result : 



F/S = ^= ^J 1 or U - nKYySTTd^ 



where 



w, the number of plates = 30 



K, the dielectric constant ..... . . . = 2*5 



V, max. potential difference = 130 C.G.S. 



d, distance between electrodes . .. = 03 cm. 



yLt, Young's modulus = 10 10 



substituting, 



M = 1G8 X 10- 7 cm. 



This value corresponds to 56 divisions of the micrometer, 

 using tripod II, or 28 divisions using tripod I. 



These results certainly are difficult to ignore and can lead 

 but to one interpretation, and that is the lack of influence o£ 

 the aether on matter in this respect. 



Dielectric Strain Perpendicular to the Lines of Force. 



Before the experiments already described in this paper 

 were begun, a series of tests for the dielectric strain perpen- 

 dicular to the lines of force was undertaken with this same 

 shellac mixture for a dielectric. The method of experi- 

 mentation and the apparatus, with the exception that the 

 cylindrical condensers were of the shellac mixture instead of 

 glass, were exactly the same as described in the Philosophical 

 Magazine, vol. vi. p. 1, 1903. Cylinders of the shellac 

 mixture were cast in a mould made of two coaxial brass 

 cylinders. Condensers of paraffin were also cast in the same 

 mould. 



Dimensions of Cylinders. 



No. 



Composition. 



Length. 



Outer 1 Inner 



chain, j cliam. 



! 



Thickness. 



p. Iv. 



7. 



Shellac. 



i 64 - 6 cm. 



4'7 cm. 3'9 cm. 



0-4 cm. 



10 10 j 2-5 



9. 



Shellac. 



;64-8 



1 

 4-7 i3-9 



025 



10 10 ! 2-5 



8. 



Paraffin. 



,' 64-8 



4-7 3-9 



0-4 



10 10 | 2-5 



