108 ANNUAL OF SCIENTIFIC DISCOVERY. 



stroke as one of two feet, like that already constructed and exhibited. 

 Prof. Page expects to make a trial upon a railroad soon, and hopes to 

 see the project of an engine and magnetic boat (not steamboat) of one 

 hundred horse-power carried out. 



As an evidence of the great power derived from electro-magnetism, 

 the following experiment was made at the Smithsonian Institution. 

 An iron bar, weighing one hundred and sixty pounds, was made to 

 spring up by magnetic action, and move rapidly through the coils up 

 and down, dancing like a feather in the air, without any visible sup- 

 port. The force operating on this bar was stated to average three 

 hundred pounds through ten inches of its motion, and could be ap- 

 plied to raise the bar one hundred feet quite as readily as through ten 

 inches. 



ON THE APPLICATION OF ELECTRO-MAGNETISM AS A MOTIVE 



POWER. 



THE following abstract of a paper read before the London Society 

 of Arts, by Robert Hunt, Esq., commends itself to the attention of 

 those interested in the application of electro-magnetism for practical 

 purposes. 



The author, after noticing the numerous and ingenious attempts 

 which have been made to apply electro-magnetism as a power for mov- 

 ing machines, states, that, notwithstanding the talent which has been 

 devoted to this interesting subject, and the large amount of money 

 which has been spent in the construction of machines, there does not 

 exist an electro-magnetic machine capable of exerting power economi- 

 cally. Finding that, notwithstanding the aid given to Jacobi by the 

 Russian government, that able experimentalist has abandoned the sub- 

 ject, the author has been induced to devote much attention to the ex- 

 amination of the first principles by which the power is regulated, with 

 the hope of being able to settle the entire question on a satisfactory 

 basis. The power of electro-magnets, it is believed, maybe increased 

 without limitation. A voltaic current produced by the chemical dis- 

 turbance of the elements of any battery, no matter what its form may 

 be, is capable of producing by induction a magnetic force, this force 

 being always in an exact ratio to the amount of matter (zinc, iro?i, or 

 otherwise) consumed in the battery. The greatest amount of this mag- 

 netic power is produced when the chemical action is the most rapid. 

 Hence, in all magnetic machines, it is more economical to employ a 

 battery in intense action than one in which the chemical action is slow. 

 It has been most satisfactorily proved that a one horse-power is ob- 

 tainable in an electro-magnetic engine, the most favorably constructed 

 to prevent loss of power, at the cost of 45 pounds of zinc, in a Grove's 

 battery, in twenty-four hours ; while 75 pounds of zinc are consumed 

 in the same time to produce the same power in a battery of Dan- 

 iell's construction. The cause of this was referred to the necessity of 

 producing a high degree of excitement to overcome the resistance 

 which the molecular forces offer to the electrical perturbations, on 

 which magnetic force depends. It was contended, that although we 



