370 Researches in Magnetic Electricity. 



trie currents from an electro-magnet. The application of the ar- 

 mature contributes to the development of magnetism, and on the 

 simultaneous withdrawal of the armature, and the galvanic cur- 

 rent, the whole amount is suddenly neutralized.* The current 

 developed by the application of the armature, I have appreciated 

 by the following experiments, and I find its consideration to be 

 of very great importance in the application of electro-magnetism 

 as a moving power. This subject will be considered at some 

 future time, and at present I shall be content with giving briefly 

 the reasons why we cannot increase the power with economy, 

 where a great number of magnets are charged by the same bat- 

 tery. 1. The motion of attracting poles towards each other, ac- 

 tually diminishes the power of each magnet, by determining a 

 current against the current of the battery. 2. The succession of 

 similar or repelling poles, determines a current also against that 

 of the battery. 3. The withdrawal of attracting poles (which 

 must be effected by mechanical power, and is of course directly 

 against an independent movement,) maintains the power of the 

 magnets, as the new current is then in favor of the battery cur- 

 rent. 



Exp. — To test the value of these secondary currents, I included 

 a galvanoscope in the circuit with an electro-magnet, and placed 

 the needle beyond the direct influence of the magnet. On bring- 

 ing up the armature, the needle returned four degrees, and on 

 suddenly applying it, the needle swung nearly back, but imme- 

 diately returned to nearly its original deflection of 40°. Sud- 

 denly pulling off the armature, the needle swung over 90°. The 

 following experiment is still more striking. Connect two electro- 

 magnets, so that they shall be charged in sequence, but at the 

 same time, and with the same battery. Load one of them with 

 about as much as it will hold. Apply the armature to the other 

 ma2;net, and the weight of the first magnet will immediately drop. 

 The same may be repeated with either magnet. The power of 

 this reacting current, as it may be called, is in proportion to the 

 number of magnets in use, charged by the same battery, the num- 



* A steel magnet gains power slowly when its poles are armed and loaded sim- 

 ply by determination, or insulation of its poles. Pulling off the armature again 

 weakens its power. Jerking it suddenly off, weakens it still further. In this case 

 the magnetic forces seem to acquire momentum, and go beyond their original sta- 

 tical development. 



