1 42 Prof. Van Breda on the Repulsion of a 



in the part b c of the floater. But the very opposite takes place ; 

 the floater moves briskly towards the points P and N, just as is 

 required by Ampere's experiment. Here, it appears to us, is a 

 result which scarcely agrees with the explanation of the motion 

 of this floater by the action of crossed currents. How, then, is it 

 to be explained, if not by Ampere's theory itself? If there is 

 any doubt on this point, we call to remembrance the experiment 

 which we published three years ago in the French journal Cosmos. 

 Permit us to describe it : — 



" One of us succeeded, twelve years ago, in showing directly 

 the repulsion of the parts of the same current, by employing a 

 dozen iron bullets 8 or 9 millims. in diameter, suspended like 

 the ivory balls in experiments on the impact of bodies, touch- 

 ing each other, and so that their centres were in the same right 

 line. By means of conductors suitably arranged and moveable 

 in mercury, the two terminal bullets could be connected with the 

 two poles of a battery ; there was besides on each a light thin 

 rod, by which their motion could be read off on a graduated 

 scale. When the current from ten Grove's elements was passed 

 through the bullets, the terminal ones were seen to diverge 

 about a millimetre, and between each pair of bullets small sparks 

 were continually seen to pass. When the battery was not too 

 strongly charged, and the action of the current not continued 

 too long, so as to prevent a permanent connexion in consequence 

 of a fusion of the bullets at the point of contact, the bullets, so 

 soon as contact was broken, were seen to approach each other 

 and resume their primitive position, which proved that the effect 

 was not due to heat, and gave a confirmation of Ampere's law at 

 once simple and direct. 



" But," you will perhaps say, " you have appealed to facts, 

 and my experiments furnish facts which demonstrate an attrac- 

 tion instead of a repulsion of the contiguous parts of the same 

 conductor." But these experiments, Sir, are they conclusive ? 

 You will permit us to doubt it. To justify this doubt, we com- 

 mence by clearly distinguishing two circumstances which are 

 confounded in your experiments, and which nevertheless are in 

 our eyes essentially different. While a conductor remains 

 charged with electricity, however strongly, it does not become 

 heated; there is no special action on the magnetic needle, 

 no chemical action is produced in its interior. It is only when 

 and whilst the electrical condition of its particles changes, and 

 whilst a current traverses it, as we usually say, that all these 

 effects are produced. These instances, and many others, would 

 prove to demonstration that there is a fundamental difference 

 between the phenomena produced by statical and dynamical 

 electricity, if a thesis so generally admitted required proof. But 



