:o;5 



Akticj.e XXVI. 



On the Aiiplkatlun of Klcctro- Magnetism to the MoreiiicDi of 

 Machines ; hij M. H. Jacobi, Doctor of Science, and Profes- 

 sor at the Universitj/ of Dorpat. 



[Published at Potsdam, 1835.] 

 PREFACE. 



A HE great discover}' of M. Oersted, which has so much extended the 

 limits of physical science, promises to open a new career to practical ihe- 

 chanics. The motive powers m hich have hitherto served for the move- 

 ment of machines are not, properly speaking, forces ; they are only 

 masses animated by forces. These masses are made to act upon the point 

 of application of a machine, and they consequently can oidy give it a 

 velocity conformable to their own moving principle. But magnetism 

 enables us to employ immediately a force ; the point of applicatiou 

 is the force itself. We thus perceive a considerable active force 

 produced without any external influence. The interest of such a phje- 

 nomenon is increased extremely by the simplicity of the apparatus 

 and by the facility of conceiving its mode of action. But on examining 

 it more closely, we find that the forces which are active in producing the 

 movement present a great complication of circumstances. The study 

 of the phEenomena of electricity and magnetism is still in its infancy ; 

 and we are not surprised that every day makes us acquainted with new 

 phsenomena at once striking and unsuspected. The views which I had 

 conceived of these forces have in part been confirmed during the course 

 of my researches, and they have in part been shaken and even com- 

 pletely changed ; as soon, however, as I was obliged to abandon one 

 view, another presented itself which led to the disclosure of fruitful re- 

 sults. For example, the remarkable reaction which prevents the move- 

 ment from becoming accelerated to infinity has become a new source 

 of power ; the exact knowledge of the galvanic action leads to a minimum 

 of the expense attending its maintenance. I have restricted myself in 

 my researches to such experiments as touch immediately upon the object 

 itself; and from the number of these, I shall only publish those which 

 have given results, or at least lead us to hope for them : I have sup- 

 pressed as much as possible all purely theoretical considerations. As to 

 the practical application, it appears to me decided by my experiments ; 

 to po furth(>r will be only to augment an effect, with which, laying 

 a«ide sanguine expectations, we may already be content. It is no un- 

 usual thing to have electro-magnets which liit iJOOOlbs.; mine carried 



