Electro-Magnetic Machine. 5 



merely to try the principle, and this construction may be superseded 

 by a different and more efficient one. But with this arrangement, 

 and notwithstanding the imperfection of the mechanism of the ma- 

 chine — when the battery, requiring about one quart of diluted acid to 

 immerse it, was attached, it lifted 16 lbs. very rapidly, and when the 

 weight was removed, it performed more than 600 revolutions per 

 minute. 



So sensible was the machine to the magnetic power, that the im- 

 mersion of the battery one inch into the acidulated water, was suffi- 

 cient to give it rapid motion, which attained its maximum, when the 

 battery was entirely immersed. It appeared to me that the machine 

 had more energy with the electro-magnets, than with those that were 

 permanent, for with the smallest battery, whose diameter was three 

 inches and a half — its height five inches and a half, and the number 

 of concentric cylinders three of copper and three of zinc, the instru- 

 ment manifested as great power as it had done with the largest batte- 

 ries, and even with a large calori motor, when it was used with a per- 

 manent instead of a galvanic magnet. With the small battery and 

 with none but electro or galvanic magnets, it revolved with so much 

 energy as to produce a brisk breeze, and powerfully to shake a large 

 table on which the apparatus stood. 



Although the magnetization of both the stationary and revolving 

 magnets was imparted by one and the same battery, the magnetic 

 power was not immediately destroyed by breaking the connexion be- 

 tween the battery and the stationary magnet ; for, when this was done, 

 the machine still performed its revolutions with great, although di- 

 minished energy ; in practice this might be important, as it would 

 give time to make changes in the apparatus, without stopping the 

 movement of the machine. 



It has been stated by Dr. Ritchie, in a late number* of the London 

 and Edinb. Phil. Magazine, that electro-magnets do not attract at so 

 great a distance as permanent ones, and therefore are not well adapt- 

 ed for producing motion. On this point Mr. Davenport made the 

 following experiment, of which 1 was not a witness, but to which I 

 give full credit, as it was reported to me by Mr. Slade, in a letter 

 dated New York, March 24, 1837. 



Mr. Davenport suspended a piece of soft iron with a long piece 

 of twine, and brought one pole of a highly charged steel magnet 



* January, 1837. 



