426 



able quantity, as in regard to currents of considerable 

 intensity and slight quantity. 



Such experiments demonstrate the utility of employing 

 an instrument the indications of which are in strict relation 

 to the forces of the current ; if the ordinary galvanometer 

 had been employed, it would have been much more difficult 

 to ascertain whether the instrument or the theory was at 

 fault. 



Having received some intimation or suggestion, I think 

 from a paragraph in a newspaper, that two voltaic currents 

 might be passed through the same conductor, it appeared 

 to me that if it were proved that two currents could pass 

 through the same wire in opposite directions, and without 

 interfering with each other, such fact might lead to im- 

 portant inferences in the theory of electricity, and that, at 

 all events, the result of experiments on this subject might 

 be of some importance in ascertaining the conducting power 

 of the various bodies. Having at hand several coils of wire 

 200 or 300 yards in length, and also electro-magnets, I 

 passed a voltaic current from a series of very small plates 

 through about 300 yards of thin wire, and also through 

 the coil of wire of an electro-magnet, consisting of about 

 30 yards of much thicker wire. A moderately delicate 

 galvanometer was connected with the small wire, and formed 

 part of the circuit; and a pint cell, according to Daniel's 

 arrangement, was connected with the coil of the magnet, 

 and I did not find that the deflections of the galvanometer 

 were sensibly affected by the more powerful current passed 

 through the coil of the magnet ; and it appeared that two 

 currents might be passed in the same, or in opposite direc- 

 tions, through the same conductor, without interfering with 

 each other. I then varied the experiments, passing currents 

 from two small voltaic pairs through considerable lengths 

 of wire, sometimes in the same, and at others in the con- 



