East and West, traversed by an Electric Current. 327 



•42 grni. for the equivalent of attractive action or apparent 

 increase of weight, and '56 grni. for that of repulsion or ap- 

 parent loss of weight. Of course such measurements, even if 

 more accurately made, would apply only to the special condi- 

 tions of the experiment as arranged. 



When the movable system of wires was placed north and 

 south, whether on the east or west side of the square, and 

 whether the current was passed from north to south or the 

 reverse, there was slight repulsion or apparent loss of weight. 

 In all positions slight lateral swings of the movable wires, in 

 all cases in the direction first described by Faraday, were 

 easily observed. 



It is proper to notice any conditions of the above experi- 

 ments which might give rise to misinterpretation of the 

 observed results : — 



1. If the movable wires were heated by the passage of the 

 electric current there would, of course, be a tendency to appa- 

 rent loss of weight by the production of an ascending gaseous 

 current in the surrounding air. This could, however, in no 

 case produce the opposite result ; and in point of fact there 

 was no sensible heating of the wire. 



2. The mutual action during the passage of the current 

 between the mercury and the ends of copper wire immersed 

 in it (which Faraday seems to have been inclined to explain by 

 changed cohesive or adhesive relations, and which Ampere 

 proposed to view as evidencing the repulsion of one section of 

 a rectilinear current by another forming its prolongation), 

 acting as it did in the same way at both ends of the movable 

 wires, caused repulsion or apparent loss of weight, thus in- 

 creasing the effect observed in this direction ; but this cause, 

 again, could never produce the opposite effect. 



3. According to the laws of Ampere there was obviously a 

 repulsive action of the w^ires of all three fixed sides of the 

 square upon the movable system ; and this repulsion involved 

 a small upward vertical component, since the movable wires 

 were suspended at a level a little above the plane in which the 

 other three sides of the square lay. The amount of this ten- 

 dency to increase of 'apparent loss of weight must have been 

 very small; and, as before, no explanation of the opposite gain 

 of weight can thence be derived. 



4. The only suggestion of possible fallacy as to the apparent 

 gain of weight seems to come from the following consideration. 

 If the lateral motion of the wire parallel to itself which Faraday 

 first described be viewed as showing simply a tendency to 

 motion in a horizontal plane, the point of suspension of the 



