134 New Ellctro-Magnetic Engine. 
years ago in this Journal, where the same device was used 
for the. purpose of intercepting the galvanic current from one 
helix or magnet, and throwing it upon a second, then a third, 
and so on in succession. ‘The bar 8, as represented in the 
figure, has nearly reached its position of equilibrium with the 
helix a, and by its motion through the helix, has carried the 
bar b’, which is attached to the same frame, into a position to be 
acted upon by the helix a’. When 0 is at its position of equi- 
librium, the crank of the fly-wheel is at one of its dead points, 
the cut-off on the shaft intercepts the galvanic current from a, 
and conducts it into a’, which then draws in the bar 6’, and thus 
a reciprocating engine is produced, which in case of the model 
above described, has three inches stroke. 
It is obvious that the helices may be made to move instead 
of the bars, but the choice would be given to the movable bars, © 
as they are in this case lighter than the helices. ‘The bars may. 
be hollow or solid—solid bars answering best—and of soft iron or 
steel, but soft iron is preferred. When the bars are of steel, im- 
mediately after using the machine with the battery, the bars are 
highly charged with magnetism, and if the battery be disen- 
_ gaged and the machine worked mechanically, it becomes a mag- 
neto-electric machine, furnishing bright sparks upon the cut-off, 
and strong shocks. In this experiment the two cups, cc, are con- 
nected by a short wire. In operating this machine by the battery, 
it exhibits one of the most beautiful, simple, and at the same time. 
most powerful movements ever produced by electro-magnetism. 
The peculiar advantages of the arrangement are as follows: 
First, a continuous action may be maintained through a very 
great distance, as will be by-and-by explained. Second, the 
retardation common to all other forms of electro-magnetic en- 
gines, cannot occur here; for as the bars to be magnetized are. 
small, they are very rapidly charged, and whatever magnetism 
they may retain after the galvanic current is intercepted in the 
helices, cannot retard their motion, as there can be no attraction 
between the copper wire of the helices and the inclosed iron bar. 
Hence with a given quantity of battery surface the maximum 
of speed and power is obtained. The retardation from the per= 
manent retention of magnetism, the time occupied in charging 
a magnet to saturation, and the time required to discharge the 
magnet, are serious obstacles in the way of obtaining any availa- 
