128 An account of the Electro- Magnetic Engine. 



the electro-magnets ; and since those gentlemen have published the 

 same to the world, it is within the power of every one versed in 

 mechanics, and acquainted with the theory of galvanism and electro- 

 magnetism, to construct electro-magnetic machines of tolerable ef- 

 ficiency. 



Besides, it is well known that the late experiments of Messrs. Jacobi 

 and Lenz have been eminently successful. The same boat, twenty- 

 eight feet long, seven and a half broad, and two and three quarter 

 deep, carrying fourteen persons, which in 1838 was set in motion by a 

 copper and zinc battery of 320 pair of plates, each plate measuring 28 

 square inches, was propelled, in the autumn of 1839, by a battery 

 of zinc and platina, on Groves's plan, consisting of 64 pair of plates, 

 each plate measuring 36 square inches, by means of a judicious altera- 

 tion in the arrangement of the bars, attained a rapidity of two miles 

 and three quarter an hour, against the stream ; being almost equal 

 to the speed of a steam-boat on the Neva, where the experiment 

 was made. In the next place, we know on good authority, that 

 an electro -magnetic machine has been long since applied in Philadel- 

 phia to the working of a printing-press ; and there can be hardly 

 any doubt but that, up to the present moment, some further progress 

 has there been made. 



Since the beginning of last year, I also have made numerous experi- 

 ments ; and am at this moment engaged in the construction of a good- 

 sized machine, according to the calculations of Messrs. Jacobi and 

 Lenz. With a view of contributing something to the diffusion of a 

 general acquaintance with this wondrous machine, I shall take the 

 liberty of communicating the following results at which 1 have 

 arrived. 



The model of an electro-magnetic machine was set in motion by means 

 of a constant battery, constructed for technical purposes, and present- 

 ing a zinc surface of ninety-nine square inches, and raised, in the space 

 of one minute, two pounds weight to a height of three feet. By means 

 of three elements, each ninety-nine square inches in superficies, the 

 same battery raised seven pounds in one minute three feet high. The 

 electro-magnets applied are in the form of bars, and care had been 

 taken that they should possess the largest polar surface possible, and 

 pass each other as closely as possible. The number of the revolutions 

 with one element amounted to 100 in one minute, and with three ele- 

 ments to 250 in the same space of time. During twelve hours of 

 unintermitting action with one element, a quarter of a pound of blue 

 vitriol was decomposed, and the copper therein contained precipitated. 



