208 Prof. E. Edlund on the 



distances from this plane the condensation on one side will be 

 eqnal to the expansion on the other. If the resistance is 

 greater in one part of the tube than in the other, the neutral 

 plane will be displaced towards the part presenting the greater 

 resistance; and the amount of the displacement will be that 

 which is requisite in order that the resistance of the whole of 

 this part (from the above-mentioned plane to the place where 

 the force acts) may become equal to the resistance of the other 

 part. If D is the density of the gas at the neutral plane, D' 

 the density in a plane situated on the side where the gas is 

 condensed, D' — D will be equal to am', in which a is a con- 

 stant, and m' is the resistance from the neutral plane to the 

 plane in question. If D" represents the density of the gas in 

 a plane situated on the other side of the neutral plane, D — D" 

 will in like manner be equal to am", if m" is the resistance 

 between these two planes. 



These well-known propositions have a direct application to 

 the circulating aether. It possesses the properties of ordinary 

 gases, in that the mobility of its molecules is considerable, so 

 as to permit it to exert equal pressure in all directions. The 

 fact that an electrified body is endowed with the same optical 

 properties as in its normal state shows, as I have remarked in 

 the above-mentioned memoir, that the elasticity of free aether 

 is proportional to its density. Therefore what has been said 

 in this investigation with regard to ordinary gases may also 

 be applied to the aether. The only difference will be that the 

 aether, whether compressed or expanded, will place itself at 

 the surface of the galvanic conductor, since the aether mole- 

 cules repel each other. 



Let us suppose a galvanic circuit in which an electromotive 

 force E excites the motion of the aether in one direction. The 

 aether will therefore become denser on the side of the electro- 

 motive force towards which the current goes, and be rarified 

 on the other side. 



The neutral plane will have a position such that the galvanic 

 resistance from this plane to the seat of the electromotive force 

 will be equal in amount on both sides. Now let i denote the 

 intensity of the current, D the density of the aether at the 

 neutral plane, or, what amounts to the same, the density of the 

 aether when it is at rest ; let D', D" be its density at any two 

 planes on the condensation side, and D' , D" its density on 

 the expansion side ; and, lastly, let m' , m" , m f , m" be' the 

 respective principal resistances from the neutral plane to the 

 planes above mentioned. As the resistance is proportional to 

 the intensity of the current, we shall evidentlv have 



D' - D = m'i, D"-D= m"i, - (D' -D) = m' i, 

 -(D" -D) = ro" t. 



