503 
ArricLe XXVI. 
On the Application of Electro-Magnetism to the Movement of 
Machines ; by M.H.Jacosi, Doctor of Science, and Profes- 
sor at the University-of Dorpat. 
[Published at Potsdam, 1835. ] 
PREFACE. 
THe great discovery of M. Oersted, which has so much extended the 
limits of physical science, promises to open a new career to practical me- 
chanics. ‘The motive powers which 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 only give it a 
velocity conformable to their own moving principle. But magnetism 
enables us to employ immediately a force; the point of application 
is the force itself. We thus perceive a considerable active force 
produced without any external influence. The interest of such'a phe- 
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 phenomena of electricity and magnetism is still in its infancy ; 
and we are not surprised that every day makes us acquainted with new 
phzenomena 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 cbliged 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 go further will be only to augment an effect, with which, laying 
aside sanguine expectations, we may already be content. It is no un- 
usual thing to have electro-magnets which lift 200Clbs.; mine carried 
